diff --git a/tests/unit/Grav/Common/AssetsTest.php b/tests/unit/Grav/Common/AssetsTest.php
index 82d26cd4b..747c8ed51 100644
--- a/tests/unit/Grav/Common/AssetsTest.php
+++ b/tests/unit/Grav/Common/AssetsTest.php
@@ -15,24 +15,24 @@ class AssetsTest extends \Codeception\TestCase\Test
     /** @var Assets $assets */
     protected $assets;
 
-    protected function _before()
+    protected function _before(): void
     {
         $grav = Fixtures::get('grav');
         $this->grav = $grav();
         $this->assets = $this->grav['assets'];
     }
 
-    protected function _after()
+    protected function _after(): void
     {
     }
 
-    public function testAddingAssets()
+    public function testAddingAssets(): void
     {
         //test add()
         $this->assets->add('test.css');
 
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         $array = $this->assets->getCss();
 
@@ -57,11 +57,11 @@ class AssetsTest extends \Codeception\TestCase\Test
               "query":""
            }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         $this->assets->add('test.js');
         $js = $this->assets->js();
-        $this->assertSame('<script src="/test.js"></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/test.js"></script>' . PHP_EOL, $js);
 
         $array = $this->assets->getJs();
 
@@ -85,13 +85,13 @@ class AssetsTest extends \Codeception\TestCase\Test
               "query":""
            }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         //test addCss(). Test adding asset to a separate group
         $this->assets->reset();
         $this->assets->addCSS('test.css');
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         $array = $this->assets->getCss();
         /** @var Assets\BaseAsset $item */
@@ -115,13 +115,13 @@ class AssetsTest extends \Codeception\TestCase\Test
               "query":""
            }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         //test addCss(). Testing with remote URL
         $this->assets->reset();
         $this->assets->addCSS('http://www.somesite.com/test.css');
         $css = $this->assets->css();
-        $this->assertSame('<link href="http://www.somesite.com/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="http://www.somesite.com/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         $array = $this->assets->getCss();
         /** @var Assets\BaseAsset $item */
@@ -144,19 +144,19 @@ class AssetsTest extends \Codeception\TestCase\Test
               "query":""
            }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         //test addCss() adding asset to a separate group, and with an alternate rel attribute
         $this->assets->reset();
         $this->assets->addCSS('test.css', ['group' => 'alternate', 'rel' => 'alternate']);
         $css = $this->assets->css('alternate');
-        $this->assertSame('<link href="/test.css" type="text/css" rel="alternate">' . PHP_EOL, $css);
+        self::assertSame('<link href="/test.css" type="text/css" rel="alternate">' . PHP_EOL, $css);
 
         //test addJs()
         $this->assets->reset();
         $this->assets->addJs('test.js');
         $js = $this->assets->js();
-        $this->assertSame('<script src="/test.js"></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/test.js"></script>' . PHP_EOL, $js);
 
         $array = $this->assets->getJs();
         /** @var Assets\BaseAsset $item */
@@ -177,15 +177,15 @@ class AssetsTest extends \Codeception\TestCase\Test
               "query":""
            }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         //Test CSS Groups
         $this->assets->reset();
         $this->assets->addCSS('test.css', ['group' => 'footer']);
         $css = $this->assets->css();
-        $this->assertEmpty($css);
+        self::assertEmpty($css);
         $css = $this->assets->css('footer');
-        $this->assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         $array = $this->assets->getCss();
         /** @var Assets\BaseAsset $item */
@@ -210,15 +210,15 @@ class AssetsTest extends \Codeception\TestCase\Test
           }
         }
         ';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         //Test JS Groups
         $this->assets->reset();
         $this->assets->addJs('test.js', ['group' => 'footer']);
         $js = $this->assets->js();
-        $this->assertEmpty($js);
+        self::assertEmpty($js);
         $js = $this->assets->js('footer');
-        $this->assertSame('<script src="/test.js"></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/test.js"></script>' . PHP_EOL, $js);
 
         $array = $this->assets->getJs();
         /** @var Assets\BaseAsset $item */
@@ -239,13 +239,13 @@ class AssetsTest extends \Codeception\TestCase\Test
             "query": ""
           }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         //Test async / defer
         $this->assets->reset();
         $this->assets->addJs('test.js', ['loading' => 'async']);
         $js = $this->assets->js();
-        $this->assertSame('<script src="/test.js" async></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/test.js" async></script>' . PHP_EOL, $js);
 
         $array = $this->assets->getJs();
         /** @var Assets\BaseAsset $item */
@@ -268,12 +268,12 @@ class AssetsTest extends \Codeception\TestCase\Test
             "query": ""
           }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         $this->assets->reset();
         $this->assets->addJs('test.js', ['loading' => 'defer']);
         $js = $this->assets->js();
-        $this->assertSame('<script src="/test.js" defer></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/test.js" defer></script>' . PHP_EOL, $js);
 
         $array = $this->assets->getJs();
         /** @var Assets\BaseAsset $item */
@@ -296,58 +296,58 @@ class AssetsTest extends \Codeception\TestCase\Test
             "query": ""
           }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         //Test inline
         $this->assets->reset();
         $this->assets->setJsPipeline(true);
         $this->assets->addJs('/system/assets/jquery/jquery-3.x.min.js');
         $js = $this->assets->js('head', ['loading' => 'inline']);
-        $this->assertStringContainsString('"jquery",[],function()', $js);
+        self::assertStringContainsString('"jquery",[],function()', $js);
 
         $this->assets->reset();
         $this->assets->setCssPipeline(true);
         $this->assets->addCss('/system/assets/debugger/phpdebugbar.css');
         $css = $this->assets->css('head', ['loading' => 'inline']);
-        $this->assertStringContainsString('div.phpdebugbar', $css);
+        self::assertStringContainsString('div.phpdebugbar', $css);
 
         $this->assets->reset();
         $this->assets->setCssPipeline(true);
         $this->assets->addCss('https://fonts.googleapis.com/css?family=Roboto');
         $css = $this->assets->css('head', ['loading' => 'inline']);
-        $this->assertStringContainsString('font-family:\'Roboto\';', $css);
+        self::assertStringContainsString('font-family:\'Roboto\';', $css);
 
         //Test adding media queries
         $this->assets->reset();
         $this->assets->add('test.css', ['media' => 'only screen and (min-width: 640px)']);
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test.css" type="text/css" rel="stylesheet" media="only screen and (min-width: 640px)">' . PHP_EOL, $css);
+        self::assertSame('<link href="/test.css" type="text/css" rel="stylesheet" media="only screen and (min-width: 640px)">' . PHP_EOL, $css);
     }
 
-    public function testAddingAssetPropertiesWithArray()
+    public function testAddingAssetPropertiesWithArray(): void
     {
         //Test adding assets with object to define properties
         $this->assets->reset();
         $this->assets->addJs('test.js', ['loading' => 'async']);
         $js = $this->assets->js();
-        $this->assertSame('<script src="/test.js" async></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/test.js" async></script>' . PHP_EOL, $js);
         $this->assets->reset();
     }
 
-    public function testAddingJSAssetPropertiesWithArrayFromCollection()
+    public function testAddingJSAssetPropertiesWithArrayFromCollection(): void
     {
         //Test adding properties with array
         $this->assets->reset();
         $this->assets->addJs('jquery', ['loading' => 'async']);
         $js = $this->assets->js();
-        $this->assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" async></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" async></script>' . PHP_EOL, $js);
 
         //Test priority too
         $this->assets->reset();
         $this->assets->addJs('jquery', ['loading' => 'async', 'priority' => 1]);
         $this->assets->addJs('test.js', ['loading' => 'async', 'priority' => 2]);
         $js = $this->assets->js();
-        $this->assertSame('<script src="/test.js" async></script>' . PHP_EOL .
+        self::assertSame('<script src="/test.js" async></script>' . PHP_EOL .
             '<script src="/system/assets/jquery/jquery-2.x.min.js" async></script>' . PHP_EOL, $js);
 
         //Test multiple groups
@@ -355,9 +355,9 @@ class AssetsTest extends \Codeception\TestCase\Test
         $this->assets->addJs('jquery', ['loading' => 'async', 'priority' => 1, 'group' => 'footer']);
         $this->assets->addJs('test.js', ['loading' => 'async', 'priority' => 2]);
         $js = $this->assets->js();
-        $this->assertSame('<script src="/test.js" async></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/test.js" async></script>' . PHP_EOL, $js);
         $js = $this->assets->js('footer');
-        $this->assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" async></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" async></script>' . PHP_EOL, $js);
 
         //Test adding array of assets
         //Test priority too
@@ -365,18 +365,18 @@ class AssetsTest extends \Codeception\TestCase\Test
         $this->assets->addJs(['jquery', 'test.js'], ['loading' => 'async']);
         $js = $this->assets->js();
 
-        $this->assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" async></script>' . PHP_EOL .
+        self::assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" async></script>' . PHP_EOL .
             '<script src="/test.js" async></script>' . PHP_EOL, $js);
     }
 
-    public function testAddingLegacyFormat()
+    public function testAddingLegacyFormat(): void
     {
         // regular CSS add
         //test addCss(). Test adding asset to a separate group
         $this->assets->reset();
         $this->assets->addCSS('test.css', 15, true, 'bottom', 'async');
         $css = $this->assets->css('bottom');
-        $this->assertSame('<link href="/test.css" type="text/css" rel="stylesheet" async>' . PHP_EOL, $css);
+        self::assertSame('<link href="/test.css" type="text/css" rel="stylesheet" async>' . PHP_EOL, $css);
 
         $array = $this->assets->getCss();
         /** @var Assets\BaseAsset $item */
@@ -401,12 +401,12 @@ class AssetsTest extends \Codeception\TestCase\Test
               "query":""
            }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
         $this->assets->reset();
         $this->assets->addJs('test.js', 15, false, 'defer', 'bottom');
         $js = $this->assets->js('bottom');
-        $this->assertSame('<script src="/test.js" defer></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/test.js" defer></script>' . PHP_EOL, $js);
 
         $array = $this->assets->getJs();
         /** @var Assets\BaseAsset $item */
@@ -429,21 +429,21 @@ class AssetsTest extends \Codeception\TestCase\Test
             "query": ""
           }
         }';
-        $this->assertJsonStringEqualsJsonString($expected, $actual);
+        self::assertJsonStringEqualsJsonString($expected, $actual);
 
 
         $this->assets->reset();
         $this->assets->addInlineCss('body { color: black }', 15, 'bottom');
         $css = $this->assets->css('bottom');
-        $this->assertSame('<style>' . PHP_EOL . 'body { color: black }' . PHP_EOL . '</style>' . PHP_EOL, $css);
+        self::assertSame('<style>' . PHP_EOL . 'body { color: black }' . PHP_EOL . '</style>' . PHP_EOL, $css);
 
         $this->assets->reset();
         $this->assets->addInlineJs('alert("test")', 15, 'bottom', ['id' => 'foo']);
         $js = $this->assets->js('bottom');
-        $this->assertSame('<script id="foo">' . PHP_EOL . 'alert("test")' . PHP_EOL . '</script>' . PHP_EOL, $js);
+        self::assertSame('<script id="foo">' . PHP_EOL . 'alert("test")' . PHP_EOL . '</script>' . PHP_EOL, $js);
     }
 
-    public function testAddingCSSAssetPropertiesWithArrayFromCollection()
+    public function testAddingCSSAssetPropertiesWithArrayFromCollection(): void
     {
         $this->assets->registerCollection('test', ['/system/assets/whoops.css']);
 
@@ -452,7 +452,7 @@ class AssetsTest extends \Codeception\TestCase\Test
         $this->assets->addCss('test', ['priority' => 1]);
         $this->assets->addCss('test.css', ['priority' => 2]);
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL .
+        self::assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL .
             '<link href="/system/assets/whoops.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         //Test multiple groups
@@ -460,27 +460,27 @@ class AssetsTest extends \Codeception\TestCase\Test
         $this->assets->addCss('test', ['priority' => 1, 'group' => 'footer']);
         $this->assets->addCss('test.css', ['priority' => 2]);
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
         $css = $this->assets->css('footer');
-        $this->assertSame('<link href="/system/assets/whoops.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="/system/assets/whoops.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         //Test adding array of assets
         //Test priority too
         $this->assets->reset();
         $this->assets->addCss(['test', 'test.css'], ['loading' => 'async']);
         $css = $this->assets->css();
-        $this->assertSame('<link href="/system/assets/whoops.css" type="text/css" rel="stylesheet" async>' . PHP_EOL .
+        self::assertSame('<link href="/system/assets/whoops.css" type="text/css" rel="stylesheet" async>' . PHP_EOL .
             '<link href="/test.css" type="text/css" rel="stylesheet" async>' . PHP_EOL, $css);
     }
 
-    public function testPriorityOfAssets()
+    public function testPriorityOfAssets(): void
     {
         $this->assets->reset();
         $this->assets->add('test.css');
         $this->assets->add('test-after.css');
 
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL .
+        self::assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL .
             '<link href="/test-after.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         //----------------
@@ -489,7 +489,7 @@ class AssetsTest extends \Codeception\TestCase\Test
         $this->assets->add('test.css', 2);
 
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL .
+        self::assertSame('<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL .
             '<link href="/test-after.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         //----------------
@@ -499,12 +499,12 @@ class AssetsTest extends \Codeception\TestCase\Test
         $this->assets->add('test-before.css', 3);
 
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test-before.css" type="text/css" rel="stylesheet">' . PHP_EOL .
+        self::assertSame('<link href="/test-before.css" type="text/css" rel="stylesheet">' . PHP_EOL .
             '<link href="/test.css" type="text/css" rel="stylesheet">' . PHP_EOL .
             '<link href="/test-after.css" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
     }
 
-    public function testPipeline()
+    public function testPipeline(): void
     {
         $this->assets->reset();
 
@@ -512,15 +512,15 @@ class AssetsTest extends \Codeception\TestCase\Test
         $this->assets->add('test.css', null, true);
         $this->assets->setCssPipeline(true);
         $css = $this->assets->css();
-        $this->assertRegExp('#<link href=\"\/assets\/(.*).css\" type=\"text\/css\" rel=\"stylesheet\">#', $css);
+        self::assertRegExp('#<link href=\"\/assets\/(.*).css\" type=\"text\/css\" rel=\"stylesheet\">#', $css);
 
         //Add a core Grav CSS file, which is found. Pipeline will now return a file
         $this->assets->add('/system/assets/debugger/phpdebugbar', null, true);
         $css = $this->assets->css();
-        $this->assertRegExp('#<link href=\"\/assets\/(.*).css\" type=\"text\/css\" rel=\"stylesheet\">#', $css);
+        self::assertRegExp('#<link href=\"\/assets\/(.*).css\" type=\"text\/css\" rel=\"stylesheet\">#', $css);
     }
 
-    public function testPipelineWithTimestamp()
+    public function testPipelineWithTimestamp(): void
     {
         $this->assets->reset();
         $this->assets->setTimestamp('foo');
@@ -529,28 +529,28 @@ class AssetsTest extends \Codeception\TestCase\Test
         //Add a core Grav CSS file, which is found. Pipeline will now return a file
         $this->assets->add('/system/assets/debugger.css', null, true);
         $css = $this->assets->css();
-        $this->assertRegExp('#<link href=\"\/assets\/(.*).css\?foo\" type=\"text\/css\" rel=\"stylesheet\">#', $css);
+        self::assertRegExp('#<link href=\"\/assets\/(.*).css\?foo\" type=\"text\/css\" rel=\"stylesheet\">#', $css);
     }
 
-    public function testInline()
+    public function testInline(): void
     {
         $this->assets->reset();
 
         //File not existing. Pipeline searches for that file without reaching it. Output is empty.
         $this->assets->add('test.css', ['loading' => 'inline']);
         $css = $this->assets->css();
-        $this->assertSame("<style>\n\n</style>\n", $css);
+        self::assertSame("<style>\n\n</style>\n", $css);
 
         $this->assets->reset();
         //Add a core Grav CSS file, which is found. Pipeline will now return its content.
         $this->assets->addCss('https://fonts.googleapis.com/css?family=Roboto', ['loading' => 'inline']);
         $this->assets->addCss('/system/assets/debugger/phpdebugbar.css', ['loading' => 'inline']);
         $css = $this->assets->css();
-        $this->assertStringContainsString('font-family: \'Roboto\';', $css);
-        $this->assertStringContainsString('div.phpdebugbar-header', $css);
+        self::assertStringContainsString('font-family: \'Roboto\';', $css);
+        self::assertStringContainsString('div.phpdebugbar-header', $css);
     }
 
-    public function testInlinePipeline()
+    public function testInlinePipeline(): void
     {
         $this->assets->reset();
         $this->assets->setCssPipeline(true);
@@ -558,216 +558,216 @@ class AssetsTest extends \Codeception\TestCase\Test
         //File not existing. Pipeline searches for that file without reaching it. Output is empty.
         $this->assets->add('test.css');
         $css = $this->assets->css('head', ['loading' => 'inline']);
-        $this->assertSame("<style>\n\n</style>\n", $css);
+        self::assertSame("<style>\n\n</style>\n", $css);
 
         //Add a core Grav CSS file, which is found. Pipeline will now return its content.
         $this->assets->addCss('https://fonts.googleapis.com/css?family=Roboto', null, true);
         $this->assets->add('/system/assets/debugger/phpdebugbar.css', null, true);
         $css = $this->assets->css('head', ['loading' => 'inline']);
-        $this->assertStringContainsString('font-family:\'Roboto\';', $css);
-        $this->assertStringContainsString('div.phpdebugbar', $css);
+        self::assertStringContainsString('font-family:\'Roboto\';', $css);
+        self::assertStringContainsString('div.phpdebugbar', $css);
     }
 
-    public function testAddAsyncJs()
+    public function testAddAsyncJs(): void
     {
         $this->assets->reset();
         $this->assets->addAsyncJs('jquery');
         $js = $this->assets->js();
-        $this->assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" async></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" async></script>' . PHP_EOL, $js);
     }
 
-    public function testAddDeferJs()
+    public function testAddDeferJs(): void
     {
         $this->assets->reset();
         $this->assets->addDeferJs('jquery');
         $js = $this->assets->js();
-        $this->assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" defer></script>' . PHP_EOL, $js);
+        self::assertSame('<script src="/system/assets/jquery/jquery-2.x.min.js" defer></script>' . PHP_EOL, $js);
     }
 
-    public function testTimestamps()
+    public function testTimestamps(): void
     {
         // local CSS nothing extra
         $this->assets->reset();
         $this->assets->setTimestamp('foo');
         $this->assets->addCSS('test.css');
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test.css?foo" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="/test.css?foo" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         // local CSS already with param
         $this->assets->reset();
         $this->assets->setTimestamp('foo');
         $this->assets->addCSS('test.css?bar');
         $css = $this->assets->css();
-        $this->assertSame('<link href="/test.css?bar&foo" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="/test.css?bar&foo" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         // external CSS already
         $this->assets->reset();
         $this->assets->setTimestamp('foo');
         $this->assets->addCSS('http://somesite.com/test.css');
         $css = $this->assets->css();
-        $this->assertSame('<link href="http://somesite.com/test.css?foo" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="http://somesite.com/test.css?foo" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         // external CSS already with param
         $this->assets->reset();
         $this->assets->setTimestamp('foo');
         $this->assets->addCSS('http://somesite.com/test.css?bar');
         $css = $this->assets->css();
-        $this->assertSame('<link href="http://somesite.com/test.css?bar&foo" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
+        self::assertSame('<link href="http://somesite.com/test.css?bar&foo" type="text/css" rel="stylesheet">' . PHP_EOL, $css);
 
         // local JS nothing extra
         $this->assets->reset();
         $this->assets->setTimestamp('foo');
         $this->assets->addJs('test.js');
         $css = $this->assets->js();
-        $this->assertSame('<script src="/test.js?foo"></script>' . PHP_EOL, $css);
+        self::assertSame('<script src="/test.js?foo"></script>' . PHP_EOL, $css);
 
         // local JS already with param
         $this->assets->reset();
         $this->assets->setTimestamp('foo');
         $this->assets->addJs('test.js?bar');
         $css = $this->assets->js();
-        $this->assertSame('<script src="/test.js?bar&foo"></script>' . PHP_EOL, $css);
+        self::assertSame('<script src="/test.js?bar&foo"></script>' . PHP_EOL, $css);
 
         // external JS already
         $this->assets->reset();
         $this->assets->setTimestamp('foo');
         $this->assets->addJs('http://somesite.com/test.js');
         $css = $this->assets->js();
-        $this->assertSame('<script src="http://somesite.com/test.js?foo"></script>' . PHP_EOL, $css);
+        self::assertSame('<script src="http://somesite.com/test.js?foo"></script>' . PHP_EOL, $css);
 
         // external JS already with param
         $this->assets->reset();
         $this->assets->setTimestamp('foo');
         $this->assets->addJs('http://somesite.com/test.js?bar');
         $css = $this->assets->js();
-        $this->assertSame('<script src="http://somesite.com/test.js?bar&foo"></script>' . PHP_EOL, $css);
+        self::assertSame('<script src="http://somesite.com/test.js?bar&foo"></script>' . PHP_EOL, $css);
     }
 
-    public function testAddInlineCss()
+    public function testAddInlineCss(): void
     {
         $this->assets->reset();
         $this->assets->addInlineCss('body { color: black }');
         $css = $this->assets->css();
-        $this->assertSame('<style>' . PHP_EOL . 'body { color: black }' . PHP_EOL . '</style>' . PHP_EOL, $css);
+        self::assertSame('<style>' . PHP_EOL . 'body { color: black }' . PHP_EOL . '</style>' . PHP_EOL, $css);
     }
 
-    public function testAddInlineJs()
+    public function testAddInlineJs(): void
     {
         $this->assets->reset();
         $this->assets->addInlineJs('alert("test")');
         $js = $this->assets->js();
-        $this->assertSame('<script>' . PHP_EOL . 'alert("test")' . PHP_EOL . '</script>' . PHP_EOL, $js);
+        self::assertSame('<script>' . PHP_EOL . 'alert("test")' . PHP_EOL . '</script>' . PHP_EOL, $js);
     }
 
-    public function testGetCollections()
+    public function testGetCollections(): void
     {
-        $this->assertIsArray($this->assets->getCollections());
-        $this->assertContains('jquery', array_keys($this->assets->getCollections()));
-        $this->assertContains('system://assets/jquery/jquery-2.x.min.js', $this->assets->getCollections());
+        self::assertIsArray($this->assets->getCollections());
+        self::assertContains('jquery', array_keys($this->assets->getCollections()));
+        self::assertContains('system://assets/jquery/jquery-2.x.min.js', $this->assets->getCollections());
     }
 
-    public function testExists()
+    public function testExists(): void
     {
-        $this->assertTrue($this->assets->exists('jquery'));
-        $this->assertFalse($this->assets->exists('another-unexisting-library'));
+        self::assertTrue($this->assets->exists('jquery'));
+        self::assertFalse($this->assets->exists('another-unexisting-library'));
     }
 
-    public function testRegisterCollection()
+    public function testRegisterCollection(): void
     {
         $this->assets->registerCollection('debugger', ['/system/assets/debugger.css']);
-        $this->assertTrue($this->assets->exists('debugger'));
-        $this->assertContains('debugger', array_keys($this->assets->getCollections()));
+        self::assertTrue($this->assets->exists('debugger'));
+        self::assertContains('debugger', array_keys($this->assets->getCollections()));
     }
 
-    public function testReset()
+    public function testReset(): void
     {
         $this->assets->addInlineJs('alert("test")');
         $this->assets->reset();
-        $this->assertCount(0, (array) $this->assets->getJs());
+        self::assertCount(0, (array) $this->assets->getJs());
 
         $this->assets->addAsyncJs('jquery');
         $this->assets->reset();
-        $this->assertCount(0, (array) $this->assets->getJs());
+        self::assertCount(0, (array) $this->assets->getJs());
 
         $this->assets->addInlineCss('body { color: black }');
         $this->assets->reset();
-        $this->assertCount(0, (array) $this->assets->getCss());
+        self::assertCount(0, (array) $this->assets->getCss());
 
         $this->assets->add('/system/assets/debugger.css', null, true);
         $this->assets->reset();
-        $this->assertCount(0, (array) $this->assets->getCss());
+        self::assertCount(0, (array) $this->assets->getCss());
     }
 
-    public function testResetJs()
+    public function testResetJs(): void
     {
         $this->assets->addInlineJs('alert("test")');
         $this->assets->resetJs();
-        $this->assertCount(0, (array) $this->assets->getJs());
+        self::assertCount(0, (array) $this->assets->getJs());
 
         $this->assets->addAsyncJs('jquery');
         $this->assets->resetJs();
-        $this->assertCount(0, (array) $this->assets->getJs());
+        self::assertCount(0, (array) $this->assets->getJs());
     }
 
-    public function testResetCss()
+    public function testResetCss(): void
     {
         $this->assets->addInlineCss('body { color: black }');
         $this->assets->resetCss();
-        $this->assertCount(0, (array) $this->assets->getCss());
+        self::assertCount(0, (array) $this->assets->getCss());
 
         $this->assets->add('/system/assets/debugger.css', null, true);
         $this->assets->resetCss();
-        $this->assertCount(0, (array) $this->assets->getCss());
+        self::assertCount(0, (array) $this->assets->getCss());
     }
 
-    public function testAddDirCss()
+    public function testAddDirCss(): void
     {
         $this->assets->addDirCss('/system');
 
-        $this->assertIsArray($this->assets->getCss());
-        $this->assertGreaterThan(0, (array) $this->assets->getCss());
-        $this->assertIsArray($this->assets->getJs());
-        $this->assertCount(0, (array) $this->assets->getJs());
+        self::assertIsArray($this->assets->getCss());
+        self::assertGreaterThan(0, (array) $this->assets->getCss());
+        self::assertIsArray($this->assets->getJs());
+        self::assertCount(0, (array) $this->assets->getJs());
 
         $this->assets->reset();
         $this->assets->addDirCss('/system/assets');
 
-        $this->assertIsArray($this->assets->getCss());
-        $this->assertGreaterThan(0, (array) $this->assets->getCss());
-        $this->assertIsArray($this->assets->getJs());
-        $this->assertCount(0, (array) $this->assets->getJs());
+        self::assertIsArray($this->assets->getCss());
+        self::assertGreaterThan(0, (array) $this->assets->getCss());
+        self::assertIsArray($this->assets->getJs());
+        self::assertCount(0, (array) $this->assets->getJs());
 
         $this->assets->reset();
         $this->assets->addDirJs('/system');
 
-        $this->assertIsArray($this->assets->getCss());
-        $this->assertCount(0, (array) $this->assets->getCss());
-        $this->assertIsArray($this->assets->getJs());
-        $this->assertGreaterThan(0, (array) $this->assets->getJs());
+        self::assertIsArray($this->assets->getCss());
+        self::assertCount(0, (array) $this->assets->getCss());
+        self::assertIsArray($this->assets->getJs());
+        self::assertGreaterThan(0, (array) $this->assets->getJs());
 
         $this->assets->reset();
         $this->assets->addDirJs('/system/assets');
 
-        $this->assertIsArray($this->assets->getCss());
-        $this->assertCount(0, (array) $this->assets->getCss());
-        $this->assertIsArray($this->assets->getJs());
-        $this->assertGreaterThan(0, (array) $this->assets->getJs());
+        self::assertIsArray($this->assets->getCss());
+        self::assertCount(0, (array) $this->assets->getCss());
+        self::assertIsArray($this->assets->getJs());
+        self::assertGreaterThan(0, (array) $this->assets->getJs());
 
         $this->assets->reset();
         $this->assets->addDir('/system/assets');
 
-        $this->assertIsArray($this->assets->getCss());
-        $this->assertGreaterThan(0, (array) $this->assets->getCss());
-        $this->assertIsArray($this->assets->getJs());
-        $this->assertGreaterThan(0, (array) $this->assets->getJs());
+        self::assertIsArray($this->assets->getCss());
+        self::assertGreaterThan(0, (array) $this->assets->getCss());
+        self::assertIsArray($this->assets->getJs());
+        self::assertGreaterThan(0, (array) $this->assets->getJs());
 
         //Use streams
         $this->assets->reset();
         $this->assets->addDir('system://assets');
 
-        $this->assertIsArray($this->assets->getCss());
-        $this->assertGreaterThan(0, (array) $this->assets->getCss());
-        $this->assertIsArray($this->assets->getJs());
-        $this->assertGreaterThan(0, (array) $this->assets->getJs());
+        self::assertIsArray($this->assets->getCss());
+        self::assertGreaterThan(0, (array) $this->assets->getCss());
+        self::assertIsArray($this->assets->getJs());
+        self::assertGreaterThan(0, (array) $this->assets->getJs());
     }
 }
diff --git a/tests/unit/Grav/Common/BrowserTest.php b/tests/unit/Grav/Common/BrowserTest.php
index a4df12003..a1033d8c9 100644
--- a/tests/unit/Grav/Common/BrowserTest.php
+++ b/tests/unit/Grav/Common/BrowserTest.php
@@ -11,41 +11,41 @@ class BrowserTest extends \Codeception\TestCase\Test
     /** @var Grav $grav */
     protected $grav;
 
-    protected function _before()
+    protected function _before(): void
     {
         $grav = Fixtures::get('grav');
         $this->grav = $grav();
     }
 
-    protected function _after()
+    protected function _after(): void
     {
     }
 
-    public function testGetBrowser()
+    public function testGetBrowser(): void
     {
  /* Already covered by PhpUserAgent tests */
     }
 
-    public function testGetPlatform()
+    public function testGetPlatform(): void
     {
  /* Already covered by PhpUserAgent tests */
     }
 
-    public function testGetLongVersion()
+    public function testGetLongVersion(): void
     {
  /* Already covered by PhpUserAgent tests */
     }
 
-    public function testGetVersion()
+    public function testGetVersion(): void
     {
  /* Already covered by PhpUserAgent tests */
     }
 
-    public function testIsHuman()
+    public function testIsHuman(): void
     {
         //Already Partially covered by PhpUserAgent tests
 
         //Make sure it recognizes the test as not human
-        $this->assertFalse($this->grav['browser']->isHuman());
+        self::assertFalse($this->grav['browser']->isHuman());
     }
 }
diff --git a/tests/unit/Grav/Common/ComposerTest.php b/tests/unit/Grav/Common/ComposerTest.php
index 67a15f47d..8c73a1fc3 100644
--- a/tests/unit/Grav/Common/ComposerTest.php
+++ b/tests/unit/Grav/Common/ComposerTest.php
@@ -5,27 +5,27 @@ use Grav\Common\Composer;
 
 class ComposerTest extends \Codeception\TestCase\Test
 {
-    protected function _before()
+    protected function _before(): void
     {
     }
 
-    protected function _after()
+    protected function _after(): void
     {
     }
 
-    public function testGetComposerLocation()
+    public function testGetComposerLocation(): void
     {
         $composerLocation = Composer::getComposerLocation();
-        $this->assertIsString($composerLocation);
-        $this->assertSame('/', $composerLocation[0]);
+        self::assertIsString($composerLocation);
+        self::assertSame('/', $composerLocation[0]);
     }
 
-    public function testGetComposerExecutor()
+    public function testGetComposerExecutor(): void
     {
         $composerExecutor = Composer::getComposerExecutor();
-        $this->assertIsString($composerExecutor);
-        $this->assertSame('/', $composerExecutor[0]);
-        $this->assertNotNull(strstr($composerExecutor, 'php'));
-        $this->assertNotNull(strstr($composerExecutor, 'composer'));
+        self::assertIsString($composerExecutor);
+        self::assertSame('/', $composerExecutor[0]);
+        self::assertNotNull(strstr($composerExecutor, 'php'));
+        self::assertNotNull(strstr($composerExecutor, 'composer'));
     }
 }
diff --git a/tests/unit/Grav/Common/Data/BlueprintTest.php b/tests/unit/Grav/Common/Data/BlueprintTest.php
index 7ffa58366..ff6ccf56e 100644
--- a/tests/unit/Grav/Common/Data/BlueprintTest.php
+++ b/tests/unit/Grav/Common/Data/BlueprintTest.php
@@ -11,7 +11,7 @@ class BlueprintTest extends \Codeception\TestCase\Test
 {
     /**
      */
-    public function testValidateStrict()
+    public function testValidateStrict(): void
     {
         $blueprint = $this->loadBlueprint('strict');
 
@@ -21,7 +21,7 @@ class BlueprintTest extends \Codeception\TestCase\Test
     /**
      * @depends testValidateStrict
      */
-    public function testValidateStrictRequired()
+    public function testValidateStrictRequired(): void
     {
         $blueprint = $this->loadBlueprint('strict');
 
@@ -32,7 +32,7 @@ class BlueprintTest extends \Codeception\TestCase\Test
     /**
      * @depends testValidateStrict
      */
-    public function testValidateStrictExtra()
+    public function testValidateStrictExtra(): void
     {
         $blueprint = $this->loadBlueprint('strict');
 
@@ -42,7 +42,7 @@ class BlueprintTest extends \Codeception\TestCase\Test
     /**
      * @depends testValidateStrict
      */
-    public function testValidateStrictExtraException()
+    public function testValidateStrictExtraException(): void
     {
         $blueprint = $this->loadBlueprint('strict');
 
@@ -61,7 +61,7 @@ class BlueprintTest extends \Codeception\TestCase\Test
      * @param string $filename
      * @return Blueprint
      */
-    protected function loadBlueprint($filename)
+    protected function loadBlueprint($filename): Blueprint
     {
         $blueprint = new Blueprint('strict');
         $blueprint->setContext(dirname(__DIR__, 3). '/data/blueprints');
diff --git a/tests/unit/Grav/Common/GPM/GPMTest.php b/tests/unit/Grav/Common/GPM/GPMTest.php
index 1fe79555e..684ed3dd1 100644
--- a/tests/unit/Grav/Common/GPM/GPMTest.php
+++ b/tests/unit/Grav/Common/GPM/GPMTest.php
@@ -7,17 +7,25 @@ use Grav\Common\GPM\GPM;
 define('EXCEPTION_BAD_FORMAT', 1);
 define('EXCEPTION_INCOMPATIBLE_VERSIONS', 2);
 
+/**
+ * Class GpmStub
+ */
 class GpmStub extends GPM
 {
+    /** @var array */
     public $data;
 
-    public function findPackage($packageName, $ignore_exception = false)
+    /**
+     * @inheritdoc
+     */
+    public function findPackage($search, $ignore_exception = false)
     {
-        if (isset($this->data[$packageName])) {
-            return $this->data[$packageName];
-        }
+        return $this->data[$search] ?? false;
     }
 
+    /**
+     * @inheritdoc
+     */
     public function findPackages($searches = [])
     {
         return $this->data;
@@ -35,17 +43,17 @@ class GpmTest extends \Codeception\TestCase\Test
     /** @var GpmStub */
     protected $gpm;
 
-    protected function _before()
+    protected function _before(): void
     {
         $this->grav = Fixtures::get('grav');
         $this->gpm = new GpmStub();
     }
 
-    protected function _after()
+    protected function _after(): void
     {
     }
 
-    public function testCalculateMergedDependenciesOfPackages()
+    public function testCalculateMergedDependenciesOfPackages(): void
     {
         //////////////////////////////////////////////////////////////////////////////////////////
         // First working example
@@ -53,22 +61,22 @@ class GpmTest extends \Codeception\TestCase\Test
         $this->gpm->data = [
             'admin' => (object)[
                 'dependencies' => [
-                    ["name" => "grav", "version" => ">=1.0.10"],
-                    ["name" => "form", "version" => "~2.0"],
-                    ["name" => "login", "version" => ">=2.0"],
-                    ["name" => "errors", "version" => "*"],
-                    ["name" => "problems"],
+                    ['name' => 'grav', 'version' => '>=1.0.10'],
+                    ['name' => 'form', 'version' => '~2.0'],
+                    ['name' => 'login', 'version' => '>=2.0'],
+                    ['name' => 'errors', 'version' => '*'],
+                    ['name' => 'problems'],
                 ]
             ],
             'test' => (object)[
                 'dependencies' => [
-                    ["name" => "errors", "version" => ">=1.0"]
+                    ['name' => 'errors', 'version' => '>=1.0']
                 ]
             ],
             'grav',
             'form' => (object)[
                 'dependencies' => [
-                    ["name" => "errors", "version" => ">=3.2"]
+                    ['name' => 'errors', 'version' => '>=3.2']
                 ]
             ]
 
@@ -79,12 +87,12 @@ class GpmTest extends \Codeception\TestCase\Test
 
         $dependencies = $this->gpm->calculateMergedDependenciesOfPackages($packages);
 
-        $this->assertIsArray($dependencies);
-        $this->assertCount(5, $dependencies);
+        self::assertIsArray($dependencies);
+        self::assertCount(5, $dependencies);
 
-        $this->assertSame('>=1.0.10', $dependencies['grav']);
-        $this->assertArrayHasKey('errors', $dependencies);
-        $this->assertArrayHasKey('problems', $dependencies);
+        self::assertSame('>=1.0.10', $dependencies['grav']);
+        self::assertArrayHasKey('errors', $dependencies);
+        self::assertArrayHasKey('problems', $dependencies);
 
         //////////////////////////////////////////////////////////////////////////////////////////
         // Second working example
@@ -92,9 +100,9 @@ class GpmTest extends \Codeception\TestCase\Test
         $packages = ['admin', 'form'];
 
         $dependencies = $this->gpm->calculateMergedDependenciesOfPackages($packages);
-        $this->assertIsArray($dependencies);
-        $this->assertCount(5, $dependencies);
-        $this->assertSame('>=3.2', $dependencies['errors']);
+        self::assertIsArray($dependencies);
+        self::assertCount(5, $dependencies);
+        self::assertSame('>=3.2', $dependencies['errors']);
 
         //////////////////////////////////////////////////////////////////////////////////////////
         // Third working example
@@ -103,17 +111,17 @@ class GpmTest extends \Codeception\TestCase\Test
 
             'admin' => (object)[
                 'dependencies' => [
-                    ["name" => "errors", "version" => ">=4.0"],
+                    ['name' => 'errors', 'version' => '>=4.0'],
                 ]
             ],
             'test' => (object)[
                 'dependencies' => [
-                    ["name" => "errors", "version" => ">=1.0"]
+                    ['name' => 'errors', 'version' => '>=1.0']
                 ]
             ],
             'another' => (object)[
                 'dependencies' => [
-                    ["name" => "errors", "version" => ">=3.2"]
+                    ['name' => 'errors', 'version' => '>=3.2']
                 ]
             ]
 
@@ -123,9 +131,9 @@ class GpmTest extends \Codeception\TestCase\Test
 
 
         $dependencies = $this->gpm->calculateMergedDependenciesOfPackages($packages);
-        $this->assertIsArray($dependencies);
-        $this->assertCount(1, $dependencies);
-        $this->assertSame('>=4.0', $dependencies['errors']);
+        self::assertIsArray($dependencies);
+        self::assertCount(1, $dependencies);
+        self::assertSame('>=4.0', $dependencies['errors']);
 
 
 
@@ -135,23 +143,23 @@ class GpmTest extends \Codeception\TestCase\Test
         $this->gpm->data = [
             'admin' => (object)[
                 'dependencies' => [
-                    ["name" => "package1", "version" => ">=4.0.0-rc1"],
-                    ["name" => "package4", "version" => ">=3.2.0"],
+                    ['name' => 'package1', 'version' => '>=4.0.0-rc1'],
+                    ['name' => 'package4', 'version' => '>=3.2.0'],
                 ]
             ],
             'test' => (object)[
                 'dependencies' => [
-                    ["name" => "package1", "version" => ">=4.0.0-rc2"],
-                    ["name" => "package2", "version" => ">=3.2.0-alpha"],
-                    ["name" => "package3", "version" => ">=3.2.0-alpha.2"],
-                    ["name" => "package4", "version" => ">=3.2.0-alpha"],
+                    ['name' => 'package1', 'version' => '>=4.0.0-rc2'],
+                    ['name' => 'package2', 'version' => '>=3.2.0-alpha'],
+                    ['name' => 'package3', 'version' => '>=3.2.0-alpha.2'],
+                    ['name' => 'package4', 'version' => '>=3.2.0-alpha'],
                 ]
             ],
             'another' => (object)[
                 'dependencies' => [
-                    ["name" => "package2", "version" => ">=3.2.0-beta.11"],
-                    ["name" => "package3", "version" => ">=3.2.0-alpha.1"],
-                    ["name" => "package4", "version" => ">=3.2.0-beta"],
+                    ['name' => 'package2', 'version' => '>=3.2.0-beta.11'],
+                    ['name' => 'package3', 'version' => '>=3.2.0-alpha.1'],
+                    ['name' => 'package4', 'version' => '>=3.2.0-beta'],
                 ]
             ]
         ];
@@ -160,10 +168,10 @@ class GpmTest extends \Codeception\TestCase\Test
 
 
         $dependencies = $this->gpm->calculateMergedDependenciesOfPackages($packages);
-        $this->assertSame('>=4.0.0-rc2', $dependencies['package1']);
-        $this->assertSame('>=3.2.0-beta.11', $dependencies['package2']);
-        $this->assertSame('>=3.2.0-alpha.2', $dependencies['package3']);
-        $this->assertSame('>=3.2.0', $dependencies['package4']);
+        self::assertSame('>=4.0.0-rc2', $dependencies['package1']);
+        self::assertSame('>=3.2.0-beta.11', $dependencies['package2']);
+        self::assertSame('>=3.2.0-alpha.2', $dependencies['package3']);
+        self::assertSame('>=3.2.0', $dependencies['package4']);
 
 
         //////////////////////////////////////////////////////////////////////////////////////////
@@ -173,12 +181,12 @@ class GpmTest extends \Codeception\TestCase\Test
 
             'admin' => (object)[
                 'dependencies' => [
-                    ["name" => "errors", "version" => ">=4.0"],
+                    ['name' => 'errors', 'version' => '>=4.0'],
                 ]
             ],
             'test' => (object)[
                 'dependencies' => [
-                    ["name" => "errors", "version" => ">="]
+                    ['name' => 'errors', 'version' => '>=']
                 ]
             ],
 
@@ -188,10 +196,10 @@ class GpmTest extends \Codeception\TestCase\Test
 
         try {
             $this->gpm->calculateMergedDependenciesOfPackages($packages);
-            $this->fail("Expected Exception not thrown");
+            self::fail('Expected Exception not thrown');
         } catch (Exception $e) {
-            $this->assertEquals(EXCEPTION_BAD_FORMAT, $e->getCode());
-            $this->assertStringStartsWith("Bad format for version of dependency", $e->getMessage());
+            self::assertEquals(EXCEPTION_BAD_FORMAT, $e->getCode());
+            self::assertStringStartsWith('Bad format for version of dependency', $e->getMessage());
         }
 
         //////////////////////////////////////////////////////////////////////////////////////////
@@ -200,12 +208,12 @@ class GpmTest extends \Codeception\TestCase\Test
         $this->gpm->data = [
             'admin' => (object)[
                 'dependencies' => [
-                    ["name" => "errors", "version" => "~4.0"],
+                    ['name' => 'errors', 'version' => '~4.0'],
                 ]
             ],
             'test' => (object)[
                 'dependencies' => [
-                    ["name" => "errors", "version" => "~3.0"]
+                    ['name' => 'errors', 'version' => '~3.0']
                 ]
             ],
         ];
@@ -214,10 +222,10 @@ class GpmTest extends \Codeception\TestCase\Test
 
         try {
             $this->gpm->calculateMergedDependenciesOfPackages($packages);
-            $this->fail("Expected Exception not thrown");
+            self::fail('Expected Exception not thrown');
         } catch (Exception $e) {
-            $this->assertEquals(EXCEPTION_INCOMPATIBLE_VERSIONS, $e->getCode());
-            $this->assertStringEndsWith("required in two incompatible versions", $e->getMessage());
+            self::assertEquals(EXCEPTION_INCOMPATIBLE_VERSIONS, $e->getCode());
+            self::assertStringEndsWith('required in two incompatible versions', $e->getMessage());
         }
 
         //////////////////////////////////////////////////////////////////////////////////////////
@@ -226,22 +234,22 @@ class GpmTest extends \Codeception\TestCase\Test
         $this->gpm->data = [
             'admin' => (object)[
                 'dependencies' => [
-                    ["name" => "grav", "version" => ">=1.0.10"],
-                    ["name" => "form", "version" => "~2.0"],
-                    ["name" => "login", "version" => ">=2.0"],
-                    ["name" => "errors", "version" => "*"],
-                    ["name" => "problems"],
+                    ['name' => 'grav', 'version' => '>=1.0.10'],
+                    ['name' => 'form', 'version' => '~2.0'],
+                    ['name' => 'login', 'version' => '>=2.0'],
+                    ['name' => 'errors', 'version' => '*'],
+                    ['name' => 'problems'],
                 ]
             ],
             'login' => (object)[
                 'dependencies' => [
-                    ["name" => "antimatter", "version" => ">=1.0"]
+                    ['name' => 'antimatter', 'version' => '>=1.0']
                 ]
             ],
             'grav',
             'antimatter' => (object)[
                 'dependencies' => [
-                    ["name" => "something", "version" => ">=3.2"]
+                    ['name' => 'something', 'version' => '>=3.2']
                 ]
             ]
 
@@ -252,71 +260,70 @@ class GpmTest extends \Codeception\TestCase\Test
 
         $dependencies = $this->gpm->calculateMergedDependenciesOfPackages($packages);
 
-        $this->assertIsArray($dependencies);
-        $this->assertCount(7, $dependencies);
+        self::assertIsArray($dependencies);
+        self::assertCount(7, $dependencies);
 
-        $this->assertSame('>=1.0.10', $dependencies['grav']);
-        $this->assertArrayHasKey('errors', $dependencies);
-        $this->assertArrayHasKey('problems', $dependencies);
-        $this->assertArrayHasKey('antimatter', $dependencies);
-        $this->assertArrayHasKey('something', $dependencies);
-        $this->assertSame('>=3.2', $dependencies['something']);
+        self::assertSame('>=1.0.10', $dependencies['grav']);
+        self::assertArrayHasKey('errors', $dependencies);
+        self::assertArrayHasKey('problems', $dependencies);
+        self::assertArrayHasKey('antimatter', $dependencies);
+        self::assertArrayHasKey('something', $dependencies);
+        self::assertSame('>=3.2', $dependencies['something']);
     }
 
-    public function testVersionFormatIsNextSignificantRelease()
+    public function testVersionFormatIsNextSignificantRelease(): void
     {
-        $this->assertFalse($this->gpm->versionFormatIsNextSignificantRelease('>=1.0'));
-        $this->assertFalse($this->gpm->versionFormatIsNextSignificantRelease('>=2.3.4'));
-        $this->assertFalse($this->gpm->versionFormatIsNextSignificantRelease('>=2.3.x'));
-        $this->assertFalse($this->gpm->versionFormatIsNextSignificantRelease('1.0'));
-        $this->assertTrue($this->gpm->versionFormatIsNextSignificantRelease('~2.3.x'));
-        $this->assertTrue($this->gpm->versionFormatIsNextSignificantRelease('~2.0'));
+        self::assertFalse($this->gpm->versionFormatIsNextSignificantRelease('>=1.0'));
+        self::assertFalse($this->gpm->versionFormatIsNextSignificantRelease('>=2.3.4'));
+        self::assertFalse($this->gpm->versionFormatIsNextSignificantRelease('>=2.3.x'));
+        self::assertFalse($this->gpm->versionFormatIsNextSignificantRelease('1.0'));
+        self::assertTrue($this->gpm->versionFormatIsNextSignificantRelease('~2.3.x'));
+        self::assertTrue($this->gpm->versionFormatIsNextSignificantRelease('~2.0'));
     }
 
-    public function testVersionFormatIsEqualOrHigher()
+    public function testVersionFormatIsEqualOrHigher(): void
     {
-        $this->assertTrue($this->gpm->versionFormatIsEqualOrHigher('>=1.0'));
-        $this->assertTrue($this->gpm->versionFormatIsEqualOrHigher('>=2.3.4'));
-        $this->assertTrue($this->gpm->versionFormatIsEqualOrHigher('>=2.3.x'));
-        $this->assertFalse($this->gpm->versionFormatIsEqualOrHigher('~2.3.x'));
-        $this->assertFalse($this->gpm->versionFormatIsEqualOrHigher('1.0'));
+        self::assertTrue($this->gpm->versionFormatIsEqualOrHigher('>=1.0'));
+        self::assertTrue($this->gpm->versionFormatIsEqualOrHigher('>=2.3.4'));
+        self::assertTrue($this->gpm->versionFormatIsEqualOrHigher('>=2.3.x'));
+        self::assertFalse($this->gpm->versionFormatIsEqualOrHigher('~2.3.x'));
+        self::assertFalse($this->gpm->versionFormatIsEqualOrHigher('1.0'));
     }
 
-    public function testCheckNextSignificantReleasesAreCompatible()
+    public function testCheckNextSignificantReleasesAreCompatible(): void
     {
         /*
          * ~1.0     is equivalent to >=1.0 < 2.0.0
          * ~1.2     is equivalent to >=1.2 <2.0.0
          * ~1.2.3   is equivalent to >=1.2.3 <1.3.0
          */
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '1.2'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.2', '1.0'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '1.0.10'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.1', '1.1.10'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('30.0', '30.10'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '1.1.10'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '1.8'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0.1', '1.1'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('2.0.0-beta', '2.0'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('2.0.0-rc.1', '2.0'));
-        $this->assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('2.0', '2.0.0-alpha'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '1.2'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.2', '1.0'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '1.0.10'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.1', '1.1.10'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('30.0', '30.10'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '1.1.10'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '1.8'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('1.0.1', '1.1'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('2.0.0-beta', '2.0'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('2.0.0-rc.1', '2.0'));
+        self::assertTrue($this->gpm->checkNextSignificantReleasesAreCompatible('2.0', '2.0.0-alpha'));
 
-        $this->assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '2.2'));
-        $this->assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('1.0.0-beta.1', '2.0'));
-        $this->assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('0.9.99', '1.0.0'));
-        $this->assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('0.9.99', '1.0.10'));
-        $this->assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('0.9.99', '1.0.10.2'));
+        self::assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('1.0', '2.2'));
+        self::assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('1.0.0-beta.1', '2.0'));
+        self::assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('0.9.99', '1.0.0'));
+        self::assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('0.9.99', '1.0.10'));
+        self::assertFalse($this->gpm->checkNextSignificantReleasesAreCompatible('0.9.99', '1.0.10.2'));
     }
 
-
-    public function testCalculateVersionNumberFromDependencyVersion()
+    public function testCalculateVersionNumberFromDependencyVersion(): void
     {
-        $this->assertSame('2.0', $this->gpm->calculateVersionNumberFromDependencyVersion('>=2.0'));
-        $this->assertSame('2.0.2', $this->gpm->calculateVersionNumberFromDependencyVersion('>=2.0.2'));
-        $this->assertSame('2.0.2', $this->gpm->calculateVersionNumberFromDependencyVersion('~2.0.2'));
-        $this->assertSame('1', $this->gpm->calculateVersionNumberFromDependencyVersion('~1'));
-        $this->assertNull($this->gpm->calculateVersionNumberFromDependencyVersion(''));
-        $this->assertNull($this->gpm->calculateVersionNumberFromDependencyVersion('*'));
-        $this->assertSame('2.0.2', $this->gpm->calculateVersionNumberFromDependencyVersion('2.0.2'));
+        self::assertSame('2.0', $this->gpm->calculateVersionNumberFromDependencyVersion('>=2.0'));
+        self::assertSame('2.0.2', $this->gpm->calculateVersionNumberFromDependencyVersion('>=2.0.2'));
+        self::assertSame('2.0.2', $this->gpm->calculateVersionNumberFromDependencyVersion('~2.0.2'));
+        self::assertSame('1', $this->gpm->calculateVersionNumberFromDependencyVersion('~1'));
+        self::assertNull($this->gpm->calculateVersionNumberFromDependencyVersion(''));
+        self::assertNull($this->gpm->calculateVersionNumberFromDependencyVersion('*'));
+        self::assertSame('2.0.2', $this->gpm->calculateVersionNumberFromDependencyVersion('2.0.2'));
     }
 }
diff --git a/tests/unit/Grav/Common/Helpers/ExcerptsTest.php b/tests/unit/Grav/Common/Helpers/ExcerptsTest.php
index 1d95f3c96..8cb473c31 100644
--- a/tests/unit/Grav/Common/Helpers/ExcerptsTest.php
+++ b/tests/unit/Grav/Common/Helpers/ExcerptsTest.php
@@ -38,7 +38,7 @@ class ExcerptsTest extends \Codeception\TestCase\Test
 
     protected $old_home;
 
-    protected function _before()
+    protected function _before(): void
     {
         $grav = Fixtures::get('grav');
         $this->grav = $grav();
@@ -70,49 +70,49 @@ class ExcerptsTest extends \Codeception\TestCase\Test
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
     }
 
-    protected function _after()
+    protected function _after(): void
     {
         $this->config->set('system.home.alias', $this->old_home);
     }
 
 
-    public function testProcessImageHtml()
+    public function testProcessImageHtml(): void
     {
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<img alt="Sample Image" src="\/images\/.*-sample-image.jpe?g\" data-src="sample-image\.jpg\?cropZoom=300,300" \/>|',
             Excerpts::processImageHtml('<img src="sample-image.jpg?cropZoom=300,300" alt="Sample Image" />', $this->page)
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<img alt="Sample Image" class="foo" src="\/images\/.*-sample-image.jpe?g\" data-src="sample-image\.jpg\?classes=foo" \/>|',
             Excerpts::processImageHtml('<img src="sample-image.jpg?classes=foo" alt="Sample Image" />', $this->page)
         );
     }
 
-    public function testNoProcess()
+    public function testNoProcess(): void
     {
-        $this->assertStringStartsWith(
+        self::assertStringStartsWith(
             '<a href="https://play.google.com/store/apps/details?hl=de" id="org.jitsi.meet" target="_blank"',
             Excerpts::processLinkHtml('<a href="https://play.google.com/store/apps/details?id=org.jitsi.meet&hl=de&target=_blank">regular process</a>')
         );
 
-        $this->assertStringStartsWith(
+        self::assertStringStartsWith(
             '<a href="https://play.google.com/store/apps/details?id=org.jitsi.meet&hl=de&target=_blank"',
             Excerpts::processLinkHtml('<a href="https://play.google.com/store/apps/details?id=org.jitsi.meet&hl=de&target=_blank&noprocess">noprocess</a>')
         );
 
-        $this->assertStringStartsWith(
+        self::assertStringStartsWith(
             '<a href="https://play.google.com/store/apps/details?id=org.jitsi.meet&hl=de" target="_blank"',
             Excerpts::processLinkHtml('<a href="https://play.google.com/store/apps/details?id=org.jitsi.meet&hl=de&target=_blank&noprocess=id">noprocess=id</a>')
         );
     }
 
-    public function testTarget()
+    public function testTarget(): void
     {
-        $this->assertStringStartsWith(
+        self::assertStringStartsWith(
             '<a href="https://play.google.com/store/apps/details" target="_blank"',
             Excerpts::processLinkHtml('<a href="https://play.google.com/store/apps/details?target=_blank">only target</a>')
         );
-        $this->assertStringStartsWith(
+        self::assertStringStartsWith(
             '<a href="https://meet.weikamp.biz/Support" rel="nofollow" target="_blank"',
             Excerpts::processLinkHtml('<a href="https://meet.weikamp.biz/Support?rel=nofollow&target=_blank">target and rel</a>')
         );
diff --git a/tests/unit/Grav/Common/InflectorTest.php b/tests/unit/Grav/Common/InflectorTest.php
index b0b1d4ad9..1db51a2aa 100644
--- a/tests/unit/Grav/Common/InflectorTest.php
+++ b/tests/unit/Grav/Common/InflectorTest.php
@@ -16,130 +16,130 @@ class InflectorTest extends \Codeception\TestCase\Test
     /** @var Inflector $uri */
     protected $inflector;
 
-    protected function _before()
+    protected function _before(): void
     {
         $grav = Fixtures::get('grav');
         $this->grav = $grav();
         $this->inflector = $this->grav['inflector'];
     }
 
-    protected function _after()
+    protected function _after(): void
     {
     }
 
-    public function testPluralize()
+    public function testPluralize(): void
     {
-        $this->assertSame('words', $this->inflector->pluralize('word'));
-        $this->assertSame('kisses', $this->inflector->pluralize('kiss'));
-        $this->assertSame('volcanoes', $this->inflector->pluralize('volcanoe'));
-        $this->assertSame('cherries', $this->inflector->pluralize('cherry'));
-        $this->assertSame('days', $this->inflector->pluralize('day'));
-        $this->assertSame('knives', $this->inflector->pluralize('knife'));
+        self::assertSame('words', $this->inflector->pluralize('word'));
+        self::assertSame('kisses', $this->inflector->pluralize('kiss'));
+        self::assertSame('volcanoes', $this->inflector->pluralize('volcanoe'));
+        self::assertSame('cherries', $this->inflector->pluralize('cherry'));
+        self::assertSame('days', $this->inflector->pluralize('day'));
+        self::assertSame('knives', $this->inflector->pluralize('knife'));
     }
 
-    public function testSingularize()
+    public function testSingularize(): void
     {
-        $this->assertSame('word', $this->inflector->singularize('words'));
-        $this->assertSame('kiss', $this->inflector->singularize('kisses'));
-        $this->assertSame('volcanoe', $this->inflector->singularize('volcanoe'));
-        $this->assertSame('cherry', $this->inflector->singularize('cherries'));
-        $this->assertSame('day', $this->inflector->singularize('days'));
-        $this->assertSame('knife', $this->inflector->singularize('knives'));
+        self::assertSame('word', $this->inflector->singularize('words'));
+        self::assertSame('kiss', $this->inflector->singularize('kisses'));
+        self::assertSame('volcanoe', $this->inflector->singularize('volcanoe'));
+        self::assertSame('cherry', $this->inflector->singularize('cherries'));
+        self::assertSame('day', $this->inflector->singularize('days'));
+        self::assertSame('knife', $this->inflector->singularize('knives'));
     }
 
-    public function testTitleize()
+    public function testTitleize(): void
     {
-        $this->assertSame('This String Is Titleized', $this->inflector->titleize('ThisStringIsTitleized'));
-        $this->assertSame('This String Is Titleized', $this->inflector->titleize('this string is titleized'));
-        $this->assertSame('This String Is Titleized', $this->inflector->titleize('this_string_is_titleized'));
-        $this->assertSame('This String Is Titleized', $this->inflector->titleize('this-string-is-titleized'));
+        self::assertSame('This String Is Titleized', $this->inflector->titleize('ThisStringIsTitleized'));
+        self::assertSame('This String Is Titleized', $this->inflector->titleize('this string is titleized'));
+        self::assertSame('This String Is Titleized', $this->inflector->titleize('this_string_is_titleized'));
+        self::assertSame('This String Is Titleized', $this->inflector->titleize('this-string-is-titleized'));
 
-        $this->assertSame('This string is titleized', $this->inflector->titleize('ThisStringIsTitleized', 'first'));
-        $this->assertSame('This string is titleized', $this->inflector->titleize('this string is titleized', 'first'));
-        $this->assertSame('This string is titleized', $this->inflector->titleize('this_string_is_titleized', 'first'));
-        $this->assertSame('This string is titleized', $this->inflector->titleize('this-string-is-titleized', 'first'));
+        self::assertSame('This string is titleized', $this->inflector->titleize('ThisStringIsTitleized', 'first'));
+        self::assertSame('This string is titleized', $this->inflector->titleize('this string is titleized', 'first'));
+        self::assertSame('This string is titleized', $this->inflector->titleize('this_string_is_titleized', 'first'));
+        self::assertSame('This string is titleized', $this->inflector->titleize('this-string-is-titleized', 'first'));
     }
 
-    public function testCamelize()
+    public function testCamelize(): void
     {
-        $this->assertSame('ThisStringIsCamelized', $this->inflector->camelize('This String Is Camelized'));
-        $this->assertSame('ThisStringIsCamelized', $this->inflector->camelize('thisStringIsCamelized'));
-        $this->assertSame('ThisStringIsCamelized', $this->inflector->camelize('This_String_Is_Camelized'));
-        $this->assertSame('ThisStringIsCamelized', $this->inflector->camelize('this string is camelized'));
-        $this->assertSame('GravSPrettyCoolMy1', $this->inflector->camelize("Grav's Pretty Cool. My #1!"));
+        self::assertSame('ThisStringIsCamelized', $this->inflector->camelize('This String Is Camelized'));
+        self::assertSame('ThisStringIsCamelized', $this->inflector->camelize('thisStringIsCamelized'));
+        self::assertSame('ThisStringIsCamelized', $this->inflector->camelize('This_String_Is_Camelized'));
+        self::assertSame('ThisStringIsCamelized', $this->inflector->camelize('this string is camelized'));
+        self::assertSame('GravSPrettyCoolMy1', $this->inflector->camelize("Grav's Pretty Cool. My #1!"));
     }
 
-    public function testUnderscorize()
+    public function testUnderscorize(): void
     {
-        $this->assertSame('this_string_is_underscorized', $this->inflector->underscorize('This String Is Underscorized'));
-        $this->assertSame('this_string_is_underscorized', $this->inflector->underscorize('ThisStringIsUnderscorized'));
-        $this->assertSame('this_string_is_underscorized', $this->inflector->underscorize('This_String_Is_Underscorized'));
-        $this->assertSame('this_string_is_underscorized', $this->inflector->underscorize('This-String-Is-Underscorized'));
+        self::assertSame('this_string_is_underscorized', $this->inflector->underscorize('This String Is Underscorized'));
+        self::assertSame('this_string_is_underscorized', $this->inflector->underscorize('ThisStringIsUnderscorized'));
+        self::assertSame('this_string_is_underscorized', $this->inflector->underscorize('This_String_Is_Underscorized'));
+        self::assertSame('this_string_is_underscorized', $this->inflector->underscorize('This-String-Is-Underscorized'));
     }
 
-    public function testHyphenize()
+    public function testHyphenize(): void
     {
-        $this->assertSame('this-string-is-hyphenized', $this->inflector->hyphenize('This String Is Hyphenized'));
-        $this->assertSame('this-string-is-hyphenized', $this->inflector->hyphenize('ThisStringIsHyphenized'));
-        $this->assertSame('this-string-is-hyphenized', $this->inflector->hyphenize('This-String-Is-Hyphenized'));
-        $this->assertSame('this-string-is-hyphenized', $this->inflector->hyphenize('This_String_Is_Hyphenized'));
+        self::assertSame('this-string-is-hyphenized', $this->inflector->hyphenize('This String Is Hyphenized'));
+        self::assertSame('this-string-is-hyphenized', $this->inflector->hyphenize('ThisStringIsHyphenized'));
+        self::assertSame('this-string-is-hyphenized', $this->inflector->hyphenize('This-String-Is-Hyphenized'));
+        self::assertSame('this-string-is-hyphenized', $this->inflector->hyphenize('This_String_Is_Hyphenized'));
     }
 
-    public function testHumanize()
+    public function testHumanize(): void
     {
-        //$this->assertSame('This string is humanized',   $this->inflector->humanize('ThisStringIsHumanized'));
-        $this->assertSame('This string is humanized', $this->inflector->humanize('this_string_is_humanized'));
-        //$this->assertSame('This string is humanized',   $this->inflector->humanize('this-string-is-humanized'));
+        //self::assertSame('This string is humanized',   $this->inflector->humanize('ThisStringIsHumanized'));
+        self::assertSame('This string is humanized', $this->inflector->humanize('this_string_is_humanized'));
+        //self::assertSame('This string is humanized',   $this->inflector->humanize('this-string-is-humanized'));
 
-        $this->assertSame('This String Is Humanized', $this->inflector->humanize('this_string_is_humanized', 'all'));
-        //$this->assertSame('This String Is Humanized',   $this->inflector->humanize('this-string-is-humanized'), 'all');
+        self::assertSame('This String Is Humanized', $this->inflector->humanize('this_string_is_humanized', 'all'));
+        //self::assertSame('This String Is Humanized',   $this->inflector->humanize('this-string-is-humanized'), 'all');
     }
 
-    public function testVariablize()
+    public function testVariablize(): void
     {
-        $this->assertSame('thisStringIsVariablized', $this->inflector->variablize('This String Is Variablized'));
-        $this->assertSame('thisStringIsVariablized', $this->inflector->variablize('ThisStringIsVariablized'));
-        $this->assertSame('thisStringIsVariablized', $this->inflector->variablize('This_String_Is_Variablized'));
-        $this->assertSame('thisStringIsVariablized', $this->inflector->variablize('this string is variablized'));
-        $this->assertSame('gravSPrettyCoolMy1', $this->inflector->variablize("Grav's Pretty Cool. My #1!"));
+        self::assertSame('thisStringIsVariablized', $this->inflector->variablize('This String Is Variablized'));
+        self::assertSame('thisStringIsVariablized', $this->inflector->variablize('ThisStringIsVariablized'));
+        self::assertSame('thisStringIsVariablized', $this->inflector->variablize('This_String_Is_Variablized'));
+        self::assertSame('thisStringIsVariablized', $this->inflector->variablize('this string is variablized'));
+        self::assertSame('gravSPrettyCoolMy1', $this->inflector->variablize("Grav's Pretty Cool. My #1!"));
     }
 
-    public function testTableize()
+    public function testTableize(): void
     {
-        $this->assertSame('people', $this->inflector->tableize('Person'));
-        $this->assertSame('pages', $this->inflector->tableize('Page'));
-        $this->assertSame('blog_pages', $this->inflector->tableize('BlogPage'));
-        $this->assertSame('admin_dependencies', $this->inflector->tableize('adminDependency'));
-        $this->assertSame('admin_dependencies', $this->inflector->tableize('admin-dependency'));
-        $this->assertSame('admin_dependencies', $this->inflector->tableize('admin_dependency'));
+        self::assertSame('people', $this->inflector->tableize('Person'));
+        self::assertSame('pages', $this->inflector->tableize('Page'));
+        self::assertSame('blog_pages', $this->inflector->tableize('BlogPage'));
+        self::assertSame('admin_dependencies', $this->inflector->tableize('adminDependency'));
+        self::assertSame('admin_dependencies', $this->inflector->tableize('admin-dependency'));
+        self::assertSame('admin_dependencies', $this->inflector->tableize('admin_dependency'));
     }
 
-    public function testClassify()
+    public function testClassify(): void
     {
-        $this->assertSame('Person', $this->inflector->classify('people'));
-        $this->assertSame('Page', $this->inflector->classify('pages'));
-        $this->assertSame('BlogPage', $this->inflector->classify('blog_pages'));
-        $this->assertSame('AdminDependency', $this->inflector->classify('admin_dependencies'));
+        self::assertSame('Person', $this->inflector->classify('people'));
+        self::assertSame('Page', $this->inflector->classify('pages'));
+        self::assertSame('BlogPage', $this->inflector->classify('blog_pages'));
+        self::assertSame('AdminDependency', $this->inflector->classify('admin_dependencies'));
     }
 
-    public function testOrdinalize()
+    public function testOrdinalize(): void
     {
-        $this->assertSame('1st', $this->inflector->ordinalize(1));
-        $this->assertSame('2nd', $this->inflector->ordinalize(2));
-        $this->assertSame('3rd', $this->inflector->ordinalize(3));
-        $this->assertSame('4th', $this->inflector->ordinalize(4));
-        $this->assertSame('5th', $this->inflector->ordinalize(5));
-        $this->assertSame('16th', $this->inflector->ordinalize(16));
-        $this->assertSame('51st', $this->inflector->ordinalize(51));
-        $this->assertSame('111th', $this->inflector->ordinalize(111));
-        $this->assertSame('123rd', $this->inflector->ordinalize(123));
+        self::assertSame('1st', $this->inflector->ordinalize(1));
+        self::assertSame('2nd', $this->inflector->ordinalize(2));
+        self::assertSame('3rd', $this->inflector->ordinalize(3));
+        self::assertSame('4th', $this->inflector->ordinalize(4));
+        self::assertSame('5th', $this->inflector->ordinalize(5));
+        self::assertSame('16th', $this->inflector->ordinalize(16));
+        self::assertSame('51st', $this->inflector->ordinalize(51));
+        self::assertSame('111th', $this->inflector->ordinalize(111));
+        self::assertSame('123rd', $this->inflector->ordinalize(123));
     }
 
-    public function testMonthize()
+    public function testMonthize(): void
     {
-        $this->assertSame(0, $this->inflector->monthize(10));
-        $this->assertSame(1, $this->inflector->monthize(33));
-        $this->assertSame(1, $this->inflector->monthize(41));
-        $this->assertSame(11, $this->inflector->monthize(364));
+        self::assertSame(0, $this->inflector->monthize(10));
+        self::assertSame(1, $this->inflector->monthize(33));
+        self::assertSame(1, $this->inflector->monthize(41));
+        self::assertSame(11, $this->inflector->monthize(364));
     }
 }
diff --git a/tests/unit/Grav/Common/Language/LanguageCodesTest.php b/tests/unit/Grav/Common/Language/LanguageCodesTest.php
index 3fbc69eb0..3450c88ea 100644
--- a/tests/unit/Grav/Common/Language/LanguageCodesTest.php
+++ b/tests/unit/Grav/Common/Language/LanguageCodesTest.php
@@ -7,21 +7,21 @@ use Grav\Common\Language\LanguageCodes;
  */
 class LanguageCodesTest extends \Codeception\TestCase\Test
 {
-    public function testRtl()
+    public function testRtl(): void
     {
-        $this->assertSame(
+        self::assertSame(
             'ltr',
             LanguageCodes::getOrientation('en')
         );
-        $this->assertSame(
+        self::assertSame(
             'rtl',
             LanguageCodes::getOrientation('ar')
         );
-        $this->assertSame(
+        self::assertSame(
             'rtl',
             LanguageCodes::getOrientation('he')
         );
-        $this->assertTrue(LanguageCodes::isRtl('ar'));
-        $this->assertFalse(LanguageCodes::isRtl('fr'));
+        self::assertTrue(LanguageCodes::isRtl('ar'));
+        self::assertFalse(LanguageCodes::isRtl('fr'));
     }
 }
diff --git a/tests/unit/Grav/Common/Markdown/ParsedownTest.php b/tests/unit/Grav/Common/Markdown/ParsedownTest.php
index 451190965..2547a0eae 100644
--- a/tests/unit/Grav/Common/Markdown/ParsedownTest.php
+++ b/tests/unit/Grav/Common/Markdown/ParsedownTest.php
@@ -35,7 +35,7 @@ class ParsedownTest extends \Codeception\TestCase\Test
 
     protected $old_home;
 
-    protected function _before()
+    protected function _before(): void
     {
         $grav = Fixtures::get('grav');
         $this->grav = $grav();
@@ -72,176 +72,176 @@ class ParsedownTest extends \Codeception\TestCase\Test
         $this->parsedown = new Parsedown($excerpts);
     }
 
-    protected function _after()
+    protected function _after(): void
     {
         $this->config->set('system.home.alias', $this->old_home);
     }
 
-    public function testImages()
+    public function testImages(): void
     {
         $this->config->set('system.languages.supported', ['fr','en']);
         unset($this->grav['language']);
         $this->grav['language'] = new Language($this->grav);
         $this->uri->initializeWithURL('http://testing.dev/fr/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" src="/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="\/images\/.*-cache-image.jpe?g\?foo=1" \/><\/p>|',
             $this->parsedown->text('![](cache-image.jpg?cropResize=200,200&foo)')
         );
 
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" src="/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="\/images\/.*-cache-image.jpe?g\?foo=1" \/><\/p>|',
             $this->parsedown->text('![](cache-image.jpg?cropResize=200,200&foo)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="\/images\/.*-home-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](/home-cache-image.jpg?cache)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="/item2/item2-2/missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](missing-image.jpg)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="/home-missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](/home-missing-image.jpg)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="/home-missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](/home-missing-image.jpg)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="https://getgrav-grav.netdna-ssl.com/user/pages/media/grav-logo.svg" alt="" /></p>',
             $this->parsedown->text('![](https://getgrav-grav.netdna-ssl.com/user/pages/media/grav-logo.svg)')
         );
     }
 
-    public function testImagesSubDir()
+    public function testImagesSubDir(): void
     {
         $this->config->set('system.images.cache_all', false);
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="\/subdir\/images\/.*-home-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](/home-cache-image.jpg?cache)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" src="/subdir/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="\/subdir\/images\/.*-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](cache-image.jpg?cache)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="/subdir/item2/item2-2/missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](missing-image.jpg)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="/subdir/home-missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](/home-missing-image.jpg)')
         );
     }
 
-    public function testImagesAbsoluteUrls()
+    public function testImagesAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" src="http://testing.dev/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="http:\/\/testing.dev\/images\/.*-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](cache-image.jpg?cache)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="http:\/\/testing.dev\/images\/.*-home-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](/home-cache-image.jpg?cache)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="http://testing.dev/item2/item2-2/missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](missing-image.jpg)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="http://testing.dev/home-missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](/home-missing-image.jpg)')
         );
     }
 
-    public function testImagesSubDirAbsoluteUrls()
+    public function testImagesSubDirAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" src="http://testing.dev/subdir/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="http:\/\/testing.dev\/subdir\/images\/.*-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](cache-image.jpg?cache)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="http:\/\/testing.dev\/subdir\/images\/.*-home-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](/home-cache-image.jpg?cropResize=200,200)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="http://testing.dev/subdir/item2/item2-2/missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](missing-image.jpg)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="http://testing.dev/subdir/home-missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](/home-missing-image.jpg)')
         );
     }
 
-    public function testImagesAttributes()
+    public function testImagesAttributes(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><img title="My Title" alt="" src="/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg "My Title")')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" class="foo" src="/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg?classes=foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" class="foo bar" src="/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg?classes=foo,bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" id="foo" src="/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg?id=foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="Alt Text" id="foo" src="/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![Alt Text](sample-image.jpg?id=foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="Alt Text" class="bar" id="foo" src="/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![Alt Text](sample-image.jpg?class=bar&id=foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img title="My Title" alt="Alt Text" class="bar" id="foo" src="/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![Alt Text](sample-image.jpg?class=bar&id=foo "My Title")')
         );
     }
 
 
-    public function testRootImages()
+    public function testRootImages(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/')->init();
 
@@ -259,19 +259,19 @@ class ParsedownTest extends \Codeception\TestCase\Test
         $excerpts = new Excerpts($page, $defaults);
         $this->parsedown = new Parsedown($excerpts);
 
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" src="/tests/fake/nested-site/user/pages/01.item1/home-sample-image.jpg" /></p>',
             $this->parsedown->text('![](home-sample-image.jpg)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="\/images\/.*-home-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](home-cache-image.jpg?cache)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="\/images\/.*-home-cache-image.jpe?g\?foo=1" \/><\/p>|',
             $this->parsedown->text('![](home-cache-image.jpg?cropResize=200,200&foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="/home-missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](/home-missing-image.jpg)')
         );
@@ -281,40 +281,40 @@ class ParsedownTest extends \Codeception\TestCase\Test
         $this->grav['language'] = new Language($this->grav);
         $this->uri->initializeWithURL('http://testing.dev/fr/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" src="/tests/fake/nested-site/user/pages/01.item1/home-sample-image.jpg" /></p>',
             $this->parsedown->text('![](home-sample-image.jpg)')
         );
     }
 
-    public function testRootImagesSubDirAbsoluteUrls()
+    public function testRootImagesSubDirAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><img alt="" src="http://testing.dev/subdir/tests/fake/nested-site/user/pages/02.item2/02.item2-2/sample-image.jpg" /></p>',
             $this->parsedown->text('![](sample-image.jpg)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="http:\/\/testing.dev\/subdir\/images\/.*-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](cache-image.jpg?cache)')
         );
-        $this->assertRegexp(
+        self::assertRegexp(
             '|<p><img alt="" src="http:\/\/testing.dev\/subdir\/images\/.*-home-cache-image.jpe?g" \/><\/p>|',
             $this->parsedown->text('![](/home-cache-image.jpg?cropResize=200,200)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="http://testing.dev/subdir/item2/item2-2/missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](missing-image.jpg)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><img src="http://testing.dev/subdir/home-missing-image.jpg" alt="" /></p>',
             $this->parsedown->text('![](/home-missing-image.jpg)')
         );
     }
 
-    public function testRootAbsoluteLinks()
+    public function testRootAbsoluteLinks(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/')->init();
 
@@ -332,25 +332,25 @@ class ParsedownTest extends \Codeception\TestCase\Test
         $excerpts = new Excerpts($page, $defaults);
         $this->parsedown = new Parsedown($excerpts);
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item1/item1-3">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](item1-3)')
         );
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](../item2)')
         );
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/?foo=bar">With Query</a></p>',
             $this->parsedown->text('[With Query](?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/foo:bar">With Param</a></p>',
             $this->parsedown->text('[With Param](/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#foo">With Anchor</a></p>',
             $this->parsedown->text('[With Anchor](#foo)')
         );
@@ -360,55 +360,55 @@ class ParsedownTest extends \Codeception\TestCase\Test
         $this->grav['language'] = new Language($this->grav);
         $this->uri->initializeWithURL('http://testing.dev/fr/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/fr/item2">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](../item2)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/fr/item1/item1-3">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](item1-3)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/fr/?foo=bar">With Query</a></p>',
             $this->parsedown->text('[With Query](?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/fr/foo:bar">With Param</a></p>',
             $this->parsedown->text('[With Param](/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#foo">With Anchor</a></p>',
             $this->parsedown->text('[With Anchor](#foo)')
         );
     }
 
 
-    public function testAnchorLinksLangRelativeUrls()
+    public function testAnchorLinksLangRelativeUrls(): void
     {
         $this->config->set('system.languages.supported', ['fr','en']);
         unset($this->grav['language']);
         $this->grav['language'] = new Language($this->grav);
         $this->uri->initializeWithURL('http://testing.dev/fr/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#foo">Current Anchor</a></p>',
             $this->parsedown->text('[Current Anchor](#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/fr/#foo">Root Anchor</a></p>',
             $this->parsedown->text('[Root Anchor](/#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/fr/item2/item2-1#foo">Peer Anchor</a></p>',
             $this->parsedown->text('[Peer Anchor](../item2-1#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/fr/item2/item2-1#foo">Peer Anchor 2</a></p>',
             $this->parsedown->text('[Peer Anchor 2](../item2-1/#foo)')
         );
     }
 
-    public function testAnchorLinksLangAbsoluteUrls()
+    public function testAnchorLinksLangAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->config->set('system.languages.supported', ['fr','en']);
@@ -416,701 +416,701 @@ class ParsedownTest extends \Codeception\TestCase\Test
         $this->grav['language'] = new Language($this->grav);
         $this->uri->initializeWithURL('http://testing.dev/fr/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#foo">Current Anchor</a></p>',
             $this->parsedown->text('[Current Anchor](#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/fr/item2/item2-1#foo">Peer Anchor</a></p>',
             $this->parsedown->text('[Peer Anchor](../item2-1#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/fr/item2/item2-1#foo">Peer Anchor 2</a></p>',
             $this->parsedown->text('[Peer Anchor 2](../item2-1/#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/fr/#foo">Root Anchor</a></p>',
             $this->parsedown->text('[Root Anchor](/#foo)')
         );
     }
 
 
-    public function testExternalLinks()
+    public function testExternalLinks(): void
     {
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://www.cnn.com">cnn.com</a></p>',
             $this->parsedown->text('[cnn.com](http://www.cnn.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="https://www.google.com">google.com</a></p>',
             $this->parsedown->text('[google.com](https://www.google.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="https://github.com/getgrav/grav/issues/new?title=%5Badd-resource%5D%20New%20Plugin%2FTheme&amp;body=Hello%20%2A%2AThere%2A%2A">complex url</a></p>',
             $this->parsedown->text('[complex url](https://github.com/getgrav/grav/issues/new?title=[add-resource]%20New%20Plugin/Theme&body=Hello%20**There**)')
         );
     }
 
-    public function testExternalLinksSubDir()
+    public function testExternalLinksSubDir(): void
     {
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://www.cnn.com">cnn.com</a></p>',
             $this->parsedown->text('[cnn.com](http://www.cnn.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="https://www.google.com">google.com</a></p>',
             $this->parsedown->text('[google.com](https://www.google.com)')
         );
     }
 
-    public function testExternalLinksSubDirAbsoluteUrls()
+    public function testExternalLinksSubDirAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://www.cnn.com">cnn.com</a></p>',
             $this->parsedown->text('[cnn.com](http://www.cnn.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="https://www.google.com">google.com</a></p>',
             $this->parsedown->text('[google.com](https://www.google.com)')
         );
     }
 
-    public function testAnchorLinksRelativeUrls()
+    public function testAnchorLinksRelativeUrls(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#foo">Current Anchor</a></p>',
             $this->parsedown->text('[Current Anchor](#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/#foo">Root Anchor</a></p>',
             $this->parsedown->text('[Root Anchor](/#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-1#foo">Peer Anchor</a></p>',
             $this->parsedown->text('[Peer Anchor](../item2-1#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-1#foo">Peer Anchor 2</a></p>',
             $this->parsedown->text('[Peer Anchor 2](../item2-1/#foo)')
         );
     }
 
-    public function testAnchorLinksAbsoluteUrls()
+    public function testAnchorLinksAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#foo">Current Anchor</a></p>',
             $this->parsedown->text('[Current Anchor](#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item2/item2-1#foo">Peer Anchor</a></p>',
             $this->parsedown->text('[Peer Anchor](../item2-1#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item2/item2-1#foo">Peer Anchor 2</a></p>',
             $this->parsedown->text('[Peer Anchor 2](../item2-1/#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/#foo">Root Anchor</a></p>',
             $this->parsedown->text('[Root Anchor](/#foo)')
         );
     }
 
-    public function testAnchorLinksWithPortAbsoluteUrls()
+    public function testAnchorLinksWithPortAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithURL('http://testing.dev:8080/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev:8080/item2/item2-1#foo">Peer Anchor</a></p>',
             $this->parsedown->text('[Peer Anchor](../item2-1#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev:8080/item2/item2-1#foo">Peer Anchor 2</a></p>',
             $this->parsedown->text('[Peer Anchor 2](../item2-1/#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#foo">Current Anchor</a></p>',
             $this->parsedown->text('[Current Anchor](#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev:8080/#foo">Root Anchor</a></p>',
             $this->parsedown->text('[Root Anchor](/#foo)')
         );
     }
 
-    public function testAnchorLinksSubDirRelativeUrls()
+    public function testAnchorLinksSubDirRelativeUrls(): void
     {
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-1#foo">Peer Anchor</a></p>',
             $this->parsedown->text('[Peer Anchor](../item2-1#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-1#foo">Peer Anchor 2</a></p>',
             $this->parsedown->text('[Peer Anchor 2](../item2-1/#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#foo">Current Anchor</a></p>',
             $this->parsedown->text('[Current Anchor](#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/#foo">Root Anchor</a></p>',
             $this->parsedown->text('[Root Anchor](/#foo)')
         );
     }
 
-    public function testAnchorLinksSubDirAbsoluteUrls()
+    public function testAnchorLinksSubDirAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-1#foo">Peer Anchor</a></p>',
             $this->parsedown->text('[Peer Anchor](../item2-1#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-1#foo">Peer Anchor 2</a></p>',
             $this->parsedown->text('[Peer Anchor 2](../item2-1/#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#foo">Current Anchor</a></p>',
             $this->parsedown->text('[Current Anchor](#foo)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/#foo">Root Anchor</a></p>',
             $this->parsedown->text('[Root Anchor](/#foo)')
         );
     }
 
-    public function testSlugRelativeLinks()
+    public function testSlugRelativeLinks(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/">Up to Root Level</a></p>',
             $this->parsedown->text('[Up to Root Level](../..)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-1">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](../item2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-2/item2-2-1">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](item2-2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2">Up a Level</a></p>',
             $this->parsedown->text('[Up a Level](..)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item3/item3-3">Up and Down</a></p>',
             $this->parsedown->text('[Up and Down](../../item3/item3-3)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-2/item2-2-1?foo=bar">Down a Level with Query</a></p>',
             $this->parsedown->text('[Down a Level with Query](item2-2-1?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2?foo=bar">Up a Level with Query</a></p>',
             $this->parsedown->text('[Up a Level with Query](../?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item3/item3-3?foo=bar">Up and Down with Query</a></p>',
             $this->parsedown->text('[Up and Down with Query](../../item3/item3-3?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item3/item3-3/foo:bar">Up and Down with Param</a></p>',
             $this->parsedown->text('[Up and Down with Param](../../item3/item3-3/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item3/item3-3#foo">Up and Down with Anchor</a></p>',
             $this->parsedown->text('[Up and Down with Anchor](../../item3/item3-3#foo)')
         );
     }
 
-    public function testSlugRelativeLinksAbsoluteUrls()
+    public function testSlugRelativeLinksAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item2/item2-1">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](../item2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item2/item2-2/item2-2-1">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](item2-2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item2">Up a Level</a></p>',
             $this->parsedown->text('[Up a Level](..)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/">Up to Root Level</a></p>',
             $this->parsedown->text('[Up to Root Level](../..)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item3/item3-3">Up and Down</a></p>',
             $this->parsedown->text('[Up and Down](../../item3/item3-3)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item2/item2-2/item2-2-1?foo=bar">Down a Level with Query</a></p>',
             $this->parsedown->text('[Down a Level with Query](item2-2-1?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item2?foo=bar">Up a Level with Query</a></p>',
             $this->parsedown->text('[Up a Level with Query](../?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item3/item3-3?foo=bar">Up and Down with Query</a></p>',
             $this->parsedown->text('[Up and Down with Query](../../item3/item3-3?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item3/item3-3/foo:bar">Up and Down with Param</a></p>',
             $this->parsedown->text('[Up and Down with Param](../../item3/item3-3/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/item3/item3-3#foo">Up and Down with Anchor</a></p>',
             $this->parsedown->text('[Up and Down with Anchor](../../item3/item3-3#foo)')
         );
     }
 
-    public function testSlugRelativeLinksSubDir()
+    public function testSlugRelativeLinksSubDir(): void
     {
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-1">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](../item2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-2/item2-2-1">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](item2-2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2">Up a Level</a></p>',
             $this->parsedown->text('[Up a Level](..)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir">Up to Root Level</a></p>',
             $this->parsedown->text('[Up to Root Level](../..)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item3/item3-3">Up and Down</a></p>',
             $this->parsedown->text('[Up and Down](../../item3/item3-3)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-2/item2-2-1?foo=bar">Down a Level with Query</a></p>',
             $this->parsedown->text('[Down a Level with Query](item2-2-1?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2?foo=bar">Up a Level with Query</a></p>',
             $this->parsedown->text('[Up a Level with Query](../?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item3/item3-3?foo=bar">Up and Down with Query</a></p>',
             $this->parsedown->text('[Up and Down with Query](../../item3/item3-3?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item3/item3-3/foo:bar">Up and Down with Param</a></p>',
             $this->parsedown->text('[Up and Down with Param](../../item3/item3-3/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item3/item3-3#foo">Up and Down with Anchor</a></p>',
             $this->parsedown->text('[Up and Down with Anchor](../../item3/item3-3#foo)')
         );
     }
 
-    public function testSlugRelativeLinksSubDirAbsoluteUrls()
+    public function testSlugRelativeLinksSubDirAbsoluteUrls(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-1">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](../item2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-2/item2-2-1">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](item2-2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2">Up a Level</a></p>',
             $this->parsedown->text('[Up a Level](..)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir">Up to Root Level</a></p>',
             $this->parsedown->text('[Up to Root Level](../..)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item3/item3-3">Up and Down</a></p>',
             $this->parsedown->text('[Up and Down](../../item3/item3-3)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-2/item2-2-1?foo=bar">Down a Level with Query</a></p>',
             $this->parsedown->text('[Down a Level with Query](item2-2-1?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2?foo=bar">Up a Level with Query</a></p>',
             $this->parsedown->text('[Up a Level with Query](../?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item3/item3-3?foo=bar">Up and Down with Query</a></p>',
             $this->parsedown->text('[Up and Down with Query](../../item3/item3-3?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item3/item3-3/foo:bar">Up and Down with Param</a></p>',
             $this->parsedown->text('[Up and Down with Param](../../item3/item3-3/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item3/item3-3#foo">Up and Down with Anchor</a></p>',
             $this->parsedown->text('[Up and Down with Anchor](../../item3/item3-3#foo)')
         );
     }
 
 
-    public function testDirectoryRelativeLinks()
+    public function testDirectoryRelativeLinks(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item3/item3-3/foo:bar">Up and Down with Param</a></p>',
             $this->parsedown->text('[Up and Down with Param](../../03.item3/03.item3-3/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-1">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](../01.item2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-2/item2-2-1">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](01.item2-2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item3/item3-3">Up and Down</a></p>',
             $this->parsedown->text('[Up and Down](../../03.item3/03.item3-3)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-2/item2-2-1?foo=bar">Down a Level with Query</a></p>',
             $this->parsedown->text('[Down a Level with Query](01.item2-2-1?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item3/item3-3?foo=bar">Up and Down with Query</a></p>',
             $this->parsedown->text('[Up and Down with Query](../../03.item3/03.item3-3?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item3/item3-3#foo">Up and Down with Anchor</a></p>',
             $this->parsedown->text('[Up and Down with Anchor](../../03.item3/03.item3-3#foo)')
         );
     }
 
 
-    public function testAbsoluteLinks()
+    public function testAbsoluteLinks(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/">Root</a></p>',
             $this->parsedown->text('[Root](/)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-1">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](/item2/item2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-2/item2-2-1">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](/item2/item2-2/item2-2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2">Up a Level</a></p>',
             $this->parsedown->text('[Up a Level](/item2)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2?foo=bar">With Query</a></p>',
             $this->parsedown->text('[With Query](/item2?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/foo:bar">With Param</a></p>',
             $this->parsedown->text('[With Param](/item2/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2#foo">With Anchor</a></p>',
             $this->parsedown->text('[With Anchor](/item2#foo)')
         );
     }
 
-    public function testDirectoryAbsoluteLinksSubDir()
+    public function testDirectoryAbsoluteLinksSubDir(): void
     {
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/">Root</a></p>',
             $this->parsedown->text('[Root](/)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-1">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](/item2/item2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-2/item2-2-1">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](/item2/item2-2/item2-2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2">Up a Level</a></p>',
             $this->parsedown->text('[Up a Level](/item2)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2?foo=bar">With Query</a></p>',
             $this->parsedown->text('[With Query](/item2?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/foo:bar">With Param</a></p>',
             $this->parsedown->text('[With Param](/item2/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2#foo">With Anchor</a></p>',
             $this->parsedown->text('[With Anchor](/item2#foo)')
         );
     }
 
-    public function testDirectoryAbsoluteLinksSubDirAbsoluteUrl()
+    public function testDirectoryAbsoluteLinksSubDirAbsoluteUrl(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/">Root</a></p>',
             $this->parsedown->text('[Root](/)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-1">Peer Page</a></p>',
             $this->parsedown->text('[Peer Page](/item2/item2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-2/item2-2-1">Down a Level</a></p>',
             $this->parsedown->text('[Down a Level](/item2/item2-2/item2-2-1)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2">Up a Level</a></p>',
             $this->parsedown->text('[Up a Level](/item2)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2?foo=bar">With Query</a></p>',
             $this->parsedown->text('[With Query](/item2?foo=bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/foo:bar">With Param</a></p>',
             $this->parsedown->text('[With Param](/item2/foo:bar)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2#foo">With Anchor</a></p>',
             $this->parsedown->text('[With Anchor](/item2#foo)')
         );
     }
 
-    public function testSpecialProtocols()
+    public function testSpecialProtocols(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="mailto:user@domain.com">mailto</a></p>',
             $this->parsedown->text('[mailto](mailto:user@domain.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="xmpp:xyx@domain.com">xmpp</a></p>',
             $this->parsedown->text('[xmpp](xmpp:xyx@domain.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="tel:123-555-12345">tel</a></p>',
             $this->parsedown->text('[tel](tel:123-555-12345)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="sms:123-555-12345">sms</a></p>',
             $this->parsedown->text('[sms](sms:123-555-12345)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="rdp://ts.example.com">ts.example.com</a></p>',
             $this->parsedown->text('[ts.example.com](rdp://ts.example.com)')
         );
     }
 
-    public function testSpecialProtocolsSubDir()
+    public function testSpecialProtocolsSubDir(): void
     {
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="mailto:user@domain.com">mailto</a></p>',
             $this->parsedown->text('[mailto](mailto:user@domain.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="xmpp:xyx@domain.com">xmpp</a></p>',
             $this->parsedown->text('[xmpp](xmpp:xyx@domain.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="tel:123-555-12345">tel</a></p>',
             $this->parsedown->text('[tel](tel:123-555-12345)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="sms:123-555-12345">sms</a></p>',
             $this->parsedown->text('[sms](sms:123-555-12345)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="rdp://ts.example.com">ts.example.com</a></p>',
             $this->parsedown->text('[ts.example.com](rdp://ts.example.com)')
         );
     }
 
-    public function testSpecialProtocolsSubDirAbsoluteUrl()
+    public function testSpecialProtocolsSubDirAbsoluteUrl(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="mailto:user@domain.com">mailto</a></p>',
             $this->parsedown->text('[mailto](mailto:user@domain.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="xmpp:xyx@domain.com">xmpp</a></p>',
             $this->parsedown->text('[xmpp](xmpp:xyx@domain.com)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="tel:123-555-12345">tel</a></p>',
             $this->parsedown->text('[tel](tel:123-555-12345)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="sms:123-555-12345">sms</a></p>',
             $this->parsedown->text('[sms](sms:123-555-12345)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="rdp://ts.example.com">ts.example.com</a></p>',
             $this->parsedown->text('[ts.example.com](rdp://ts.example.com)')
         );
     }
 
-    public function testReferenceLinks()
+    public function testReferenceLinks(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
         $sample = '[relative link][r_relative]
                    [r_relative]: ../item2-3#blah';
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-3#blah">relative link</a></p>',
             $this->parsedown->text($sample)
         );
 
         $sample = '[absolute link][r_absolute]
                    [r_absolute]: /item3#blah';
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item3#blah">absolute link</a></p>',
             $this->parsedown->text($sample)
         );
 
         $sample = '[external link][r_external]
                    [r_external]: http://www.cnn.com';
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://www.cnn.com">external link</a></p>',
             $this->parsedown->text($sample)
         );
     }
 
-    public function testAttributeLinks()
+    public function testAttributeLinks(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="#something" class="button">Anchor Class</a></p>',
             $this->parsedown->text('[Anchor Class](?classes=button#something)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-3" class="button">Relative Class</a></p>',
             $this->parsedown->text('[Relative Class](../item2-3?classes=button)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-3" id="unique">Relative ID</a></p>',
             $this->parsedown->text('[Relative ID](../item2-3?id=unique)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="https://github.com/getgrav/grav" class="button big">External</a></p>',
             $this->parsedown->text('[External](https://github.com/getgrav/grav?classes=button,big)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-3?id=unique">Relative Noprocess</a></p>',
             $this->parsedown->text('[Relative Noprocess](../item2-3?id=unique&noprocess)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-3" target="_blank">Relative Target</a></p>',
             $this->parsedown->text('[Relative Target](../item2-3?target=_blank)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-3" rel="nofollow">Relative Rel</a></p>',
             $this->parsedown->text('[Relative Rel](../item2-3?rel=nofollow)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-3?foo=bar&amp;baz=qux" rel="nofollow" class="button">Relative Mixed</a></p>',
             $this->parsedown->text('[Relative Mixed](../item2-3?foo=bar&baz=qux&rel=nofollow&class=button)')
         );
     }
 
-    public function testInvalidLinks()
+    public function testInvalidLinks(): void
     {
         $this->uri->initializeWithURL('http://testing.dev/item2/item2-2')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-2/no-page">Non Existent Page</a></p>',
             $this->parsedown->text('[Non Existent Page](no-page)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-2/existing-file.zip">Existent File</a></p>',
             $this->parsedown->text('[Existent File](existing-file.zip)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/item2/item2-2/missing-file.zip">Non Existent File</a></p>',
             $this->parsedown->text('[Non Existent File](missing-file.zip)')
         );
     }
 
-    public function testInvalidLinksSubDir()
+    public function testInvalidLinksSubDir(): void
     {
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-2/no-page">Non Existent Page</a></p>',
             $this->parsedown->text('[Non Existent Page](no-page)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-2/existing-file.zip">Existent File</a></p>',
             $this->parsedown->text('[Existent File](existing-file.zip)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="/subdir/item2/item2-2/missing-file.zip">Non Existent File</a></p>',
             $this->parsedown->text('[Non Existent File](missing-file.zip)')
         );
     }
 
-    public function testInvalidLinksSubDirAbsoluteUrl()
+    public function testInvalidLinksSubDirAbsoluteUrl(): void
     {
         $this->config->set('system.absolute_urls', true);
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/item2/item2-2', '/subdir')->init();
 
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-2/no-page">Non Existent Page</a></p>',
             $this->parsedown->text('[Non Existent Page](no-page)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-2/existing-file.zip">Existent File</a></p>',
             $this->parsedown->text('[Existent File](existing-file.zip)')
         );
-        $this->assertSame(
+        self::assertSame(
             '<p><a href="http://testing.dev/subdir/item2/item2-2/missing-file.zip">Non Existent File</a></p>',
             $this->parsedown->text('[Non Existent File](missing-file.zip)')
         );
diff --git a/tests/unit/Grav/Common/Page/PagesTest.php b/tests/unit/Grav/Common/Page/PagesTest.php
index b53ca8414..6301a1b3d 100644
--- a/tests/unit/Grav/Common/Page/PagesTest.php
+++ b/tests/unit/Grav/Common/Page/PagesTest.php
@@ -21,7 +21,7 @@ class PagesTest extends \Codeception\TestCase\Test
     /** @var PageInterface $root_page */
     protected $root_page;
 
-    protected function _before()
+    protected function _before(): void
     {
         $grav = Fixtures::get('grav');
         $this->grav = $grav();
@@ -35,46 +35,46 @@ class PagesTest extends \Codeception\TestCase\Test
         $this->pages->init();
     }
 
-    public function testBase()
+    public function testBase(): void
     {
-        $this->assertSame('', $this->pages->base());
+        self::assertSame('', $this->pages->base());
         $this->pages->base('/test');
-        $this->assertSame('/test', $this->pages->base());
+        self::assertSame('/test', $this->pages->base());
         $this->pages->base('');
-        $this->assertSame($this->pages->base(), '');
+        self::assertSame($this->pages->base(), '');
     }
 
-    public function testLastModified()
+    public function testLastModified(): void
     {
-        $this->assertNull($this->pages->lastModified());
+        self::assertNull($this->pages->lastModified());
         $this->pages->lastModified('test');
-        $this->assertSame('test', $this->pages->lastModified());
+        self::assertSame('test', $this->pages->lastModified());
     }
 
-    public function testInstances()
+    public function testInstances(): void
     {
-        $this->assertIsArray($this->pages->instances());
+        self::assertIsArray($this->pages->instances());
         foreach ($this->pages->instances() as $instance) {
-            $this->assertInstanceOf(PageInterface::class, $instance);
+            self::assertInstanceOf(PageInterface::class, $instance);
         }
     }
 
-    public function testRoutes()
+    public function testRoutes(): void
     {
         /** @var UniformResourceLocator $locator */
         $locator = $this->grav['locator'];
         $folder = $locator->findResource('tests://');
 
-        $this->assertIsArray($this->pages->routes());
-        $this->assertSame($folder . '/fake/simple-site/user/pages/01.home', $this->pages->routes()['/']);
-        $this->assertSame($folder . '/fake/simple-site/user/pages/01.home', $this->pages->routes()['/home']);
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog', $this->pages->routes()['/blog']);
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', $this->pages->routes()['/blog/post-one']);
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', $this->pages->routes()['/blog/post-two']);
-        $this->assertSame($folder . '/fake/simple-site/user/pages/03.about', $this->pages->routes()['/about']);
+        self::assertIsArray($this->pages->routes());
+        self::assertSame($folder . '/fake/simple-site/user/pages/01.home', $this->pages->routes()['/']);
+        self::assertSame($folder . '/fake/simple-site/user/pages/01.home', $this->pages->routes()['/home']);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog', $this->pages->routes()['/blog']);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', $this->pages->routes()['/blog/post-one']);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', $this->pages->routes()['/blog/post-two']);
+        self::assertSame($folder . '/fake/simple-site/user/pages/03.about', $this->pages->routes()['/about']);
     }
 
-    public function testAddPage()
+    public function testAddPage(): void
     {
         /** @var UniformResourceLocator $locator */
         $locator = $this->grav['locator'];
@@ -86,11 +86,11 @@ class PagesTest extends \Codeception\TestCase\Test
 
         $this->pages->addPage($aPage, '/new-page');
 
-        $this->assertContains('/new-page', array_keys($this->pages->routes()));
-        $this->assertSame($folder . '/fake/single-pages/01.simple-page', $this->pages->routes()['/new-page']);
+        self::assertContains('/new-page', array_keys($this->pages->routes()));
+        self::assertSame($folder . '/fake/single-pages/01.simple-page', $this->pages->routes()['/new-page']);
     }
 
-    public function testSort()
+    public function testSort(): void
     {
         /** @var UniformResourceLocator $locator */
         $locator = $this->grav['locator'];
@@ -99,34 +99,34 @@ class PagesTest extends \Codeception\TestCase\Test
         $aPage = $this->pages->find('/blog');
         $subPagesSorted = $this->pages->sort($aPage);
 
-        $this->assertIsArray($subPagesSorted);
-        $this->assertCount(2, $subPagesSorted);
+        self::assertIsArray($subPagesSorted);
+        self::assertCount(2, $subPagesSorted);
 
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted)[0]);
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted)[1]);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted)[0]);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted)[1]);
 
-        $this->assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted));
-        $this->assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted));
+        self::assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted));
+        self::assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted));
 
-        $this->assertSame(['slug' => 'post-one'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-one']);
-        $this->assertSame(['slug' => 'post-two'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-two']);
+        self::assertSame(['slug' => 'post-one'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-one']);
+        self::assertSame(['slug' => 'post-two'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-two']);
 
         $subPagesSorted = $this->pages->sort($aPage, null, 'desc');
 
-        $this->assertIsArray($subPagesSorted);
-        $this->assertCount(2, $subPagesSorted);
+        self::assertIsArray($subPagesSorted);
+        self::assertCount(2, $subPagesSorted);
 
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted)[0]);
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted)[1]);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted)[0]);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted)[1]);
 
-        $this->assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted));
-        $this->assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted));
+        self::assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted));
+        self::assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted));
 
-        $this->assertSame(['slug' => 'post-one'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-one']);
-        $this->assertSame(['slug' => 'post-two'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-two']);
+        self::assertSame(['slug' => 'post-one'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-one']);
+        self::assertSame(['slug' => 'post-two'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-two']);
     }
 
-    public function testSortCollection()
+    public function testSortCollection(): void
     {
         /** @var UniformResourceLocator $locator */
         $locator = $this->grav['locator'];
@@ -135,34 +135,34 @@ class PagesTest extends \Codeception\TestCase\Test
         $aPage = $this->pages->find('/blog');
         $subPagesSorted = $this->pages->sortCollection($aPage->children(), $aPage->orderBy());
 
-        $this->assertIsArray($subPagesSorted);
-        $this->assertCount(2, $subPagesSorted);
+        self::assertIsArray($subPagesSorted);
+        self::assertCount(2, $subPagesSorted);
 
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted)[0]);
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted)[1]);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted)[0]);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted)[1]);
 
-        $this->assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted));
-        $this->assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted));
+        self::assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted));
+        self::assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted));
 
-        $this->assertSame(['slug' => 'post-one'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-one']);
-        $this->assertSame(['slug' => 'post-two'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-two']);
+        self::assertSame(['slug' => 'post-one'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-one']);
+        self::assertSame(['slug' => 'post-two'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-two']);
 
         $subPagesSorted = $this->pages->sortCollection($aPage->children(), $aPage->orderBy(), 'desc');
 
-        $this->assertIsArray($subPagesSorted);
-        $this->assertCount(2, $subPagesSorted);
+        self::assertIsArray($subPagesSorted);
+        self::assertCount(2, $subPagesSorted);
 
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted)[0]);
-        $this->assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted)[1]);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted)[0]);
+        self::assertSame($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted)[1]);
 
-        $this->assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted));
-        $this->assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted));
+        self::assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-one', array_keys($subPagesSorted));
+        self::assertContains($folder . '/fake/simple-site/user/pages/02.blog/post-two', array_keys($subPagesSorted));
 
-        $this->assertSame(['slug' => 'post-one'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-one']);
-        $this->assertSame(['slug' => 'post-two'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-two']);
+        self::assertSame(['slug' => 'post-one'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-one']);
+        self::assertSame(['slug' => 'post-two'], $subPagesSorted[$folder . '/fake/simple-site/user/pages/02.blog/post-two']);
     }
 
-    public function testGet()
+    public function testGet(): void
     {
         /** @var UniformResourceLocator $locator */
         $locator = $this->grav['locator'];
@@ -170,14 +170,14 @@ class PagesTest extends \Codeception\TestCase\Test
 
         //Page existing
         $aPage = $this->pages->get($folder . '/fake/simple-site/user/pages/03.about');
-        $this->assertInstanceOf(PageInterface::class, $aPage);
+        self::assertInstanceOf(PageInterface::class, $aPage);
 
         //Page not existing
         $anotherPage = $this->pages->get($folder . '/fake/simple-site/user/pages/03.non-existing');
-        $this->assertNull($anotherPage);
+        self::assertNull($anotherPage);
     }
 
-    public function testChildren()
+    public function testChildren(): void
     {
         /** @var UniformResourceLocator $locator */
         $locator = $this->grav['locator'];
@@ -185,90 +185,90 @@ class PagesTest extends \Codeception\TestCase\Test
 
         //Page existing
         $children = $this->pages->children($folder . '/fake/simple-site/user/pages/02.blog');
-        $this->assertInstanceOf('Grav\Common\Page\Collection', $children);
+        self::assertInstanceOf('Grav\Common\Page\Collection', $children);
 
         //Page not existing
         $children = $this->pages->children($folder . '/fake/whatever/non-existing');
-        $this->assertSame([], $children->toArray());
+        self::assertSame([], $children->toArray());
     }
 
-    public function testDispatch()
+    public function testDispatch(): void
     {
         $aPage = $this->pages->dispatch('/blog');
-        $this->assertInstanceOf(PageInterface::class, $aPage);
+        self::assertInstanceOf(PageInterface::class, $aPage);
 
         $aPage = $this->pages->dispatch('/about');
-        $this->assertInstanceOf(PageInterface::class, $aPage);
+        self::assertInstanceOf(PageInterface::class, $aPage);
 
         $aPage = $this->pages->dispatch('/blog/post-one');
-        $this->assertInstanceOf(PageInterface::class, $aPage);
+        self::assertInstanceOf(PageInterface::class, $aPage);
 
         //Page not existing
         $aPage = $this->pages->dispatch('/non-existing');
-        $this->assertNull($aPage);
+        self::assertNull($aPage);
     }
 
-    public function testRoot()
+    public function testRoot(): void
     {
         $root = $this->pages->root();
-        $this->assertInstanceOf(PageInterface::class, $root);
-        $this->assertSame('pages', $root->folder());
+        self::assertInstanceOf(PageInterface::class, $root);
+        self::assertSame('pages', $root->folder());
     }
 
-    public function testBlueprints()
+    public function testBlueprints(): void
     {
     }
 
     public function testAll()
     {
-        $this->assertIsObject($this->pages->all());
-        $this->assertIsArray($this->pages->all()->toArray());
+        self::assertIsObject($this->pages->all());
+        self::assertIsArray($this->pages->all()->toArray());
         foreach ($this->pages->all() as $page) {
-            $this->assertInstanceOf(PageInterface::class, $page);
+            self::assertInstanceOf(PageInterface::class, $page);
         }
     }
 
-    public function testGetList()
+    public function testGetList(): void
     {
         $list = $this->pages->getList();
-        $this->assertIsArray($list);
-        $this->assertSame('&mdash;-&rtrif; Home', $list['/']);
-        $this->assertSame('&mdash;-&rtrif; Blog', $list['/blog']);
+        self::assertIsArray($list);
+        self::assertSame('&mdash;-&rtrif; Home', $list['/']);
+        self::assertSame('&mdash;-&rtrif; Blog', $list['/blog']);
     }
 
-    public function testGetTypes()
+    public function testGetTypes(): void
     {
     }
 
-    public function testTypes()
+    public function testTypes(): void
     {
     }
 
-    public function testModularTypes()
+    public function testModularTypes(): void
     {
     }
 
-    public function testPageTypes()
+    public function testPageTypes(): void
     {
     }
 
-    public function testAccessLevels()
+    public function testAccessLevels(): void
     {
     }
 
-    public function testParents()
+    public function testParents(): void
     {
     }
 
-    public function testParentsRawRoutes()
+    public function testParentsRawRoutes(): void
     {
     }
 
-    public function testGetHomeRoute()
+    public function testGetHomeRoute(): void
     {
     }
 
-    public function testResetPages()
+    public function testResetPages(): void
     {
     }
 }
diff --git a/tests/unit/Grav/Common/Twig/TwigExtensionTest.php b/tests/unit/Grav/Common/Twig/TwigExtensionTest.php
index d7ccdd7f8..4062675d2 100644
--- a/tests/unit/Grav/Common/Twig/TwigExtensionTest.php
+++ b/tests/unit/Grav/Common/Twig/TwigExtensionTest.php
@@ -15,44 +15,44 @@ class TwigExtensionTest extends \Codeception\TestCase\Test
     /** @var  TwigExtension $twig_ext */
     protected $twig_ext;
 
-    protected function _before()
+    protected function _before(): void
     {
         $this->grav = Fixtures::get('grav');
         $this->twig_ext = new TwigExtension();
     }
 
-    public function testInflectorFilter()
+    public function testInflectorFilter(): void
     {
-        $this->assertSame('people', $this->twig_ext->inflectorFilter('plural', 'person'));
-        $this->assertSame('shoe', $this->twig_ext->inflectorFilter('singular', 'shoes'));
-        $this->assertSame('Welcome Page', $this->twig_ext->inflectorFilter('title', 'welcome page'));
-        $this->assertSame('SendEmail', $this->twig_ext->inflectorFilter('camel', 'send_email'));
-        $this->assertSame('camel_cased', $this->twig_ext->inflectorFilter('underscor', 'CamelCased'));
-        $this->assertSame('something-text', $this->twig_ext->inflectorFilter('hyphen', 'Something Text'));
-        $this->assertSame('Something text to read', $this->twig_ext->inflectorFilter('human', 'something_text_to_read'));
-        $this->assertSame(5, $this->twig_ext->inflectorFilter('month', '175'));
-        $this->assertSame('10th', $this->twig_ext->inflectorFilter('ordinal', '10'));
+        self::assertSame('people', $this->twig_ext->inflectorFilter('plural', 'person'));
+        self::assertSame('shoe', $this->twig_ext->inflectorFilter('singular', 'shoes'));
+        self::assertSame('Welcome Page', $this->twig_ext->inflectorFilter('title', 'welcome page'));
+        self::assertSame('SendEmail', $this->twig_ext->inflectorFilter('camel', 'send_email'));
+        self::assertSame('camel_cased', $this->twig_ext->inflectorFilter('underscor', 'CamelCased'));
+        self::assertSame('something-text', $this->twig_ext->inflectorFilter('hyphen', 'Something Text'));
+        self::assertSame('Something text to read', $this->twig_ext->inflectorFilter('human', 'something_text_to_read'));
+        self::assertSame(5, $this->twig_ext->inflectorFilter('month', '175'));
+        self::assertSame('10th', $this->twig_ext->inflectorFilter('ordinal', '10'));
     }
 
-    public function testMd5Filter()
+    public function testMd5Filter(): void
     {
-        $this->assertSame(md5('grav'), $this->twig_ext->md5Filter('grav'));
-        $this->assertSame(md5('devs@getgrav.org'), $this->twig_ext->md5Filter('devs@getgrav.org'));
+        self::assertSame(md5('grav'), $this->twig_ext->md5Filter('grav'));
+        self::assertSame(md5('devs@getgrav.org'), $this->twig_ext->md5Filter('devs@getgrav.org'));
     }
 
-    public function testKsortFilter()
+    public function testKsortFilter(): void
     {
         $object = array("name"=>"Bob","age"=>8,"colour"=>"red");
-        $this->assertSame(array("age"=>8,"colour"=>"red","name"=>"Bob"), $this->twig_ext->ksortFilter($object));
+        self::assertSame(array("age"=>8,"colour"=>"red","name"=>"Bob"), $this->twig_ext->ksortFilter($object));
     }
 
-    public function testContainsFilter()
+    public function testContainsFilter(): void
     {
-        $this->assertTrue($this->twig_ext->containsFilter('grav', 'grav'));
-        $this->assertTrue($this->twig_ext->containsFilter('So, I found this new cms, called grav, and it\'s pretty awesome guys', 'grav'));
+        self::assertTrue($this->twig_ext->containsFilter('grav', 'grav'));
+        self::assertTrue($this->twig_ext->containsFilter('So, I found this new cms, called grav, and it\'s pretty awesome guys', 'grav'));
     }
 
-    public function testNicetimeFilter()
+    public function testNicetimeFilter(): void
     {
         $now = time();
         $threeMinutes = time() - (60*3);
@@ -62,121 +62,121 @@ class TwigExtensionTest extends \Codeception\TestCase\Test
         $threeYears   = time() - (60*60*24*365*3);
         $measures = ['minutes','hours','days','months','years'];
 
-        $this->assertSame('No date provided', $this->twig_ext->nicetimeFunc(null));
+        self::assertSame('No date provided', $this->twig_ext->nicetimeFunc(null));
 
         for ($i=0; $i<count($measures); $i++) {
             $time = 'three' . ucfirst($measures[$i]);
-            $this->assertSame('3 ' . $measures[$i] . ' ago', $this->twig_ext->nicetimeFunc($$time));
+            self::assertSame('3 ' . $measures[$i] . ' ago', $this->twig_ext->nicetimeFunc($$time));
         }
     }
 
-    public function testRandomizeFilter()
+    public function testRandomizeFilter(): void
     {
         $array = [1,2,3,4,5];
-        $this->assertContains(2, $this->twig_ext->randomizeFilter($array));
-        $this->assertSame($array, $this->twig_ext->randomizeFilter($array, 5));
-        $this->assertSame($array[0], $this->twig_ext->randomizeFilter($array, 1)[0]);
-        $this->assertSame($array[3], $this->twig_ext->randomizeFilter($array, 4)[3]);
-        $this->assertSame($array[1], $this->twig_ext->randomizeFilter($array, 4)[1]);
+        self::assertContains(2, $this->twig_ext->randomizeFilter($array));
+        self::assertSame($array, $this->twig_ext->randomizeFilter($array, 5));
+        self::assertSame($array[0], $this->twig_ext->randomizeFilter($array, 1)[0]);
+        self::assertSame($array[3], $this->twig_ext->randomizeFilter($array, 4)[3]);
+        self::assertSame($array[1], $this->twig_ext->randomizeFilter($array, 4)[1]);
     }
 
-    public function testModulusFilter()
+    public function testModulusFilter(): void
     {
-        $this->assertSame(3, $this->twig_ext->modulusFilter(3, 4));
-        $this->assertSame(1, $this->twig_ext->modulusFilter(11, 2));
-        $this->assertSame(0, $this->twig_ext->modulusFilter(10, 2));
-        $this->assertSame(2, $this->twig_ext->modulusFilter(10, 4));
+        self::assertSame(3, $this->twig_ext->modulusFilter(3, 4));
+        self::assertSame(1, $this->twig_ext->modulusFilter(11, 2));
+        self::assertSame(0, $this->twig_ext->modulusFilter(10, 2));
+        self::assertSame(2, $this->twig_ext->modulusFilter(10, 4));
     }
 
-    public function testAbsoluteUrlFilter()
+    public function testAbsoluteUrlFilter(): void
     {
     }
 
-    public function testMarkdownFilter()
+    public function testMarkdownFilter(): void
     {
     }
 
-    public function testStartsWithFilter()
+    public function testStartsWithFilter(): void
     {
     }
 
-    public function testEndsWithFilter()
+    public function testEndsWithFilter(): void
     {
     }
 
-    public function testDefinedDefaultFilter()
+    public function testDefinedDefaultFilter(): void
     {
     }
 
-    public function testRtrimFilter()
+    public function testRtrimFilter(): void
     {
     }
 
-    public function testLtrimFilter()
+    public function testLtrimFilter(): void
     {
     }
 
-    public function testRepeatFunc()
+    public function testRepeatFunc(): void
     {
     }
 
-    public function testRegexReplace()
+    public function testRegexReplace(): void
     {
     }
 
-    public function testUrlFunc()
+    public function testUrlFunc(): void
     {
     }
 
-    public function testEvaluateFunc()
+    public function testEvaluateFunc(): void
     {
     }
 
-    public function testDump()
+    public function testDump(): void
     {
     }
 
-    public function testGistFunc()
+    public function testGistFunc(): void
     {
     }
 
-    public function testRandomStringFunc()
+    public function testRandomStringFunc(): void
     {
     }
 
-    public function testPadFilter()
+    public function testPadFilter(): void
     {
     }
 
-    public function testArrayFunc()
+    public function testArrayFunc(): void
     {
-        $this->assertSame(
+        self::assertSame(
             'this is my text',
             $this->twig_ext->regexReplace('<p>this is my text</p>', '(<\/?p>)', '')
         );
-        $this->assertSame(
+        self::assertSame(
             '<i>this is my text</i>',
             $this->twig_ext->regexReplace('<p>this is my text</p>', ['(<p>)','(<\/p>)'], ['<i>','</i>'])
         );
     }
 
-    public function testArrayKeyValue()
+    public function testArrayKeyValue(): void
     {
-        $this->assertSame(
+        self::assertSame(
             ['meat' => 'steak'],
             $this->twig_ext->arrayKeyValueFunc('meat', 'steak')
         );
-        $this->assertSame(
+        self::assertSame(
             ['fruit' => 'apple', 'meat' => 'steak'],
             $this->twig_ext->arrayKeyValueFunc('meat', 'steak', ['fruit' => 'apple'])
         );
     }
 
-    public function stringFunc()
+    public function stringFunc(): void
     {
     }
 
-    public function testRangeFunc()
+    public function testRangeFunc(): void
     {
         $hundred = [];
         for ($i = 0; $i <= 100; $i++) {
@@ -184,19 +184,19 @@ class TwigExtensionTest extends \Codeception\TestCase\Test
         }
 
 
-        $this->assertSame([0], $this->twig_ext->rangeFunc(0, 0));
-        $this->assertSame([0, 1, 2], $this->twig_ext->rangeFunc(0, 2));
+        self::assertSame([0], $this->twig_ext->rangeFunc(0, 0));
+        self::assertSame([0, 1, 2], $this->twig_ext->rangeFunc(0, 2));
 
-        $this->assertSame([0, 5, 10, 15], $this->twig_ext->rangeFunc(0, 16, 5));
+        self::assertSame([0, 5, 10, 15], $this->twig_ext->rangeFunc(0, 16, 5));
 
         // default (min 0, max 100, step 1)
-        $this->assertSame($hundred, $this->twig_ext->rangeFunc());
+        self::assertSame($hundred, $this->twig_ext->rangeFunc());
 
         // 95 items, starting from 5, (min 5, max 100, step 1)
-        $this->assertSame(array_slice($hundred, 5), $this->twig_ext->rangeFunc(5));
+        self::assertSame(array_slice($hundred, 5), $this->twig_ext->rangeFunc(5));
 
         // reversed range
-        $this->assertSame(array_reverse($hundred), $this->twig_ext->rangeFunc(100, 0));
-        $this->assertSame([4, 2, 0], $this->twig_ext->rangeFunc(4, 0, 2));
+        self::assertSame(array_reverse($hundred), $this->twig_ext->rangeFunc(100, 0));
+        self::assertSame([4, 2, 0], $this->twig_ext->rangeFunc(4, 0, 2));
     }
 }
diff --git a/tests/unit/Grav/Common/UriTest.php b/tests/unit/Grav/Common/UriTest.php
index cec8eb62c..8f1601a6f 100644
--- a/tests/unit/Grav/Common/UriTest.php
+++ b/tests/unit/Grav/Common/UriTest.php
@@ -854,18 +854,18 @@ class UriTest extends \Codeception\TestCase\Test
         ],
     ];
 
-    protected function _before()
+    protected function _before(): void
     {
         $grav = Fixtures::get('grav');
         $this->grav = $grav();
         $this->uri = $this->grav['uri'];
     }
 
-    protected function _after()
+    protected function _after(): void
     {
     }
 
-    protected function runTestSet(array $tests, $method, $params = [])
+    protected function runTestSet(array $tests, $method, $params = []): void
     {
         foreach ($tests as $url => $candidates) {
             if (!array_key_exists($method, $candidates) && $method !== 'toOriginalString') {
@@ -875,7 +875,7 @@ class UriTest extends \Codeception\TestCase\Test
                 $nonce = Utils::getNonce('test-action');
                 $expected = str_replace('{{nonce}}', $nonce, $candidates[$method]);
 
-                $this->assertSame($expected, Uri::addNonce($url, 'test-action'));
+                self::assertSame($expected, Uri::addNonce($url, 'test-action'));
 
                 continue;
             }
@@ -893,213 +893,213 @@ class UriTest extends \Codeception\TestCase\Test
                 $result = $this->uri->{$method}();
             }
 
-            $this->assertSame($expected, $result, "Test \$url->{$method}() for {$url}");
+            self::assertSame($expected, $result, "Test \$url->{$method}() for {$url}");
             // Deal with $url->query($key)
             if ($method === 'query') {
                 parse_str($expected, $queryParams);
                 foreach ($queryParams as $key => $value) {
-                    $this->assertSame($value, $this->uri->{$method}($key), "Test \$url->{$method}('{$key}') for {$url}");
+                    self::assertSame($value, $this->uri->{$method}($key), "Test \$url->{$method}('{$key}') for {$url}");
                 }
-                $this->assertNull($this->uri->{$method}('non-existing'), "Test \$url->{$method}('non-existing') for {$url}");
+                self::assertNull($this->uri->{$method}('non-existing'), "Test \$url->{$method}('non-existing') for {$url}");
             }
         }
     }
 
-    public function testValidatingHostname()
+    public function testValidatingHostname(): void
     {
-        $this->assertTrue($this->uri->validateHostname('localhost'));
-        $this->assertTrue($this->uri->validateHostname('google.com'));
-        $this->assertTrue($this->uri->validateHostname('google.it'));
-        $this->assertTrue($this->uri->validateHostname('goog.le'));
-        $this->assertTrue($this->uri->validateHostname('goog.wine'));
-        $this->assertTrue($this->uri->validateHostname('goog.localhost'));
+        self::assertTrue($this->uri->validateHostname('localhost'));
+        self::assertTrue($this->uri->validateHostname('google.com'));
+        self::assertTrue($this->uri->validateHostname('google.it'));
+        self::assertTrue($this->uri->validateHostname('goog.le'));
+        self::assertTrue($this->uri->validateHostname('goog.wine'));
+        self::assertTrue($this->uri->validateHostname('goog.localhost'));
 
-        $this->assertFalse($this->uri->validateHostname('localhost:80'));
-        $this->assertFalse($this->uri->validateHostname('http://localhost'));
-        $this->assertFalse($this->uri->validateHostname('localhost!'));
+        self::assertFalse($this->uri->validateHostname('localhost:80'));
+        self::assertFalse($this->uri->validateHostname('http://localhost'));
+        self::assertFalse($this->uri->validateHostname('localhost!'));
     }
 
-    public function testToString()
+    public function testToString(): void
     {
         $this->runTestSet($this->tests, 'toOriginalString');
     }
 
-    public function testScheme()
+    public function testScheme(): void
     {
         $this->runTestSet($this->tests, 'scheme');
     }
 
-    public function testUser()
+    public function testUser(): void
     {
         $this->runTestSet($this->tests, 'user');
     }
 
-    public function testPassword()
+    public function testPassword(): void
     {
         $this->runTestSet($this->tests, 'password');
     }
 
-    public function testHost()
+    public function testHost(): void
     {
         $this->runTestSet($this->tests, 'host');
     }
 
-    public function testPort()
+    public function testPort(): void
     {
         $this->runTestSet($this->tests, 'port');
     }
 
-    public function testPath()
+    public function testPath(): void
     {
         $this->runTestSet($this->tests, 'path');
     }
 
-    public function testQuery()
+    public function testQuery(): void
     {
         $this->runTestSet($this->tests, 'query');
     }
 
-    public function testFragment()
+    public function testFragment(): void
     {
         $this->runTestSet($this->tests, 'fragment');
 
         $this->uri->fragment('something-new');
-        $this->assertSame('something-new', $this->uri->fragment());
+        self::assertSame('something-new', $this->uri->fragment());
     }
 
-    public function testPaths()
+    public function testPaths(): void
     {
         $this->runTestSet($this->tests, 'paths');
     }
 
-    public function testRoute()
+    public function testRoute(): void
     {
         $this->runTestSet($this->tests, 'route');
     }
 
-    public function testParams()
+    public function testParams(): void
     {
         $this->runTestSet($this->tests, 'params');
 
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper:xxx')->init();
-        $this->assertSame('/ueper:xxx', $this->uri->params('ueper'));
+        self::assertSame('/ueper:xxx', $this->uri->params('ueper'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper:xxx/test:yyy')->init();
-        $this->assertSame('/ueper:xxx', $this->uri->params('ueper'));
-        $this->assertSame('/test:yyy', $this->uri->params('test'));
+        self::assertSame('/ueper:xxx', $this->uri->params('ueper'));
+        self::assertSame('/test:yyy', $this->uri->params('test'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper:xxx++/test:yyy')->init();
-        $this->assertSame('/ueper:xxx++/test:yyy', $this->uri->params());
-        $this->assertSame('/ueper:xxx++', $this->uri->params('ueper'));
-        $this->assertSame('/test:yyy', $this->uri->params('test'));
+        self::assertSame('/ueper:xxx++/test:yyy', $this->uri->params());
+        self::assertSame('/ueper:xxx++', $this->uri->params('ueper'));
+        self::assertSame('/test:yyy', $this->uri->params('test'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper:xxx++/test:yyy#something')->init();
-        $this->assertSame('/ueper:xxx++/test:yyy', $this->uri->params());
-        $this->assertSame('/ueper:xxx++', $this->uri->params('ueper'));
-        $this->assertSame('/test:yyy', $this->uri->params('test'));
+        self::assertSame('/ueper:xxx++/test:yyy', $this->uri->params());
+        self::assertSame('/ueper:xxx++', $this->uri->params('ueper'));
+        self::assertSame('/test:yyy', $this->uri->params('test'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper:xxx++/test:yyy?foo=bar')->init();
-        $this->assertSame('/ueper:xxx++/test:yyy', $this->uri->params());
-        $this->assertSame('/ueper:xxx++', $this->uri->params('ueper'));
-        $this->assertSame('/test:yyy', $this->uri->params('test'));
+        self::assertSame('/ueper:xxx++/test:yyy', $this->uri->params());
+        self::assertSame('/ueper:xxx++', $this->uri->params('ueper'));
+        self::assertSame('/test:yyy', $this->uri->params('test'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper?test=x')->init();
-        $this->assertNull($this->uri->params());
-        $this->assertNull($this->uri->params('ueper'));
+        self::assertNull($this->uri->params());
+        self::assertNull($this->uri->params('ueper'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper?test=x&test2=y')->init();
-        $this->assertNull($this->uri->params());
-        $this->assertNull($this->uri->params('ueper'));
+        self::assertNull($this->uri->params());
+        self::assertNull($this->uri->params('ueper'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper?test=x&test2=y&test3=x&test4=y')->init();
-        $this->assertNull($this->uri->params());
-        $this->assertNull($this->uri->params('ueper'));
+        self::assertNull($this->uri->params());
+        self::assertNull($this->uri->params('ueper'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper?test=x&test2=y&test3=x&test4=y/test')->init();
-        $this->assertNull($this->uri->params());
-        $this->assertNull($this->uri->params('ueper'));
+        self::assertNull($this->uri->params());
+        self::assertNull($this->uri->params('ueper'));
         $this->uri->initializeWithURL('http://localhost:8080/a/b/c/d')->init();
-        $this->assertNull($this->uri->params());
-        $this->assertNull($this->uri->params('ueper'));
+        self::assertNull($this->uri->params());
+        self::assertNull($this->uri->params('ueper'));
         $this->uri->initializeWithURL('http://localhost:8080/a/b/c/d/e/f/a/b/c/d/e/f/a/b/c/d/e/f')->init();
-        $this->assertNull($this->uri->params());
-        $this->assertNull($this->uri->params('ueper'));
+        self::assertNull($this->uri->params());
+        self::assertNull($this->uri->params('ueper'));
     }
 
-    public function testParam()
+    public function testParam(): void
     {
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper:xxx')->init();
-        $this->assertSame('xxx', $this->uri->param('ueper'));
+        self::assertSame('xxx', $this->uri->param('ueper'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper:xxx/test:yyy')->init();
-        $this->assertSame('xxx', $this->uri->param('ueper'));
-        $this->assertSame('yyy', $this->uri->param('test'));
+        self::assertSame('xxx', $this->uri->param('ueper'));
+        self::assertSame('yyy', $this->uri->param('test'));
         $this->uri->initializeWithURL('http://localhost:8080/grav/it/ueper:xxx++/test:yy%20y/foo:bar_baz-bank')->init();
-        $this->assertSame('xxx++', $this->uri->param('ueper'));
-        $this->assertSame('yy y', $this->uri->param('test'));
-        $this->assertSame('bar_baz-bank', $this->uri->param('foo'));
+        self::assertSame('xxx++', $this->uri->param('ueper'));
+        self::assertSame('yy y', $this->uri->param('test'));
+        self::assertSame('bar_baz-bank', $this->uri->param('foo'));
     }
 
-    public function testUrl()
+    public function testUrl(): void
     {
         $this->runTestSet($this->tests, 'url');
     }
 
-    public function testExtension()
+    public function testExtension(): void
     {
         $this->runTestSet($this->tests, 'extension');
 
         $this->uri->initializeWithURL('http://localhost/a-page')->init();
-        $this->assertSame('x', $this->uri->extension('x'));
+        self::assertSame('x', $this->uri->extension('x'));
     }
 
-    public function testEnvironment()
+    public function testEnvironment(): void
     {
         $this->runTestSet($this->tests, 'environment');
     }
 
-    public function testBasename()
+    public function testBasename(): void
     {
         $this->runTestSet($this->tests, 'basename');
     }
 
-    public function testBase()
+    public function testBase(): void
     {
         $this->runTestSet($this->tests, 'base');
     }
 
-    public function testRootUrl()
+    public function testRootUrl(): void
     {
         $this->runTestSet($this->tests, 'rootUrl', [true]);
 
         $this->uri->initializeWithUrlAndRootPath('https://localhost/grav/page-foo', '/grav')->init();
-        $this->assertSame('/grav', $this->uri->rootUrl());
-        $this->assertSame('https://localhost/grav', $this->uri->rootUrl(true));
+        self::assertSame('/grav', $this->uri->rootUrl());
+        self::assertSame('https://localhost/grav', $this->uri->rootUrl(true));
     }
 
-    public function testCurrentPage()
+    public function testCurrentPage(): void
     {
         $this->runTestSet($this->tests, 'currentPage');
 
         $this->uri->initializeWithURL('http://localhost:8080/a-page/page:2')->init();
-        $this->assertSame(2, $this->uri->currentPage());
+        self::assertSame(2, $this->uri->currentPage());
     }
 
-    public function testReferrer()
+    public function testReferrer(): void
     {
         $this->uri->initializeWithURL('http://localhost/foo/page:test')->init();
-        $this->assertSame('/foo', $this->uri->referrer());
+        self::assertSame('/foo', $this->uri->referrer());
         $this->uri->initializeWithURL('http://localhost/foo/bar/page:test')->init();
-        $this->assertSame('/foo/bar', $this->uri->referrer());
+        self::assertSame('/foo/bar', $this->uri->referrer());
     }
 
-    public function testIp()
+    public function testIp(): void
     {
         $this->uri->initializeWithURL('http://localhost/foo/page:test')->init();
-        $this->assertSame('UNKNOWN', Uri::ip());
+        self::assertSame('UNKNOWN', Uri::ip());
     }
 
-    public function testIsExternal()
+    public function testIsExternal(): void
     {
         $this->uri->initializeWithURL('http://localhost/')->init();
-        $this->assertFalse(Uri::isExternal('/test'));
-        $this->assertFalse(Uri::isExternal('/foo/bar'));
-        $this->assertTrue(Uri::isExternal('http://localhost/test'));
-        $this->assertTrue(Uri::isExternal('http://google.it/test'));
+        self::assertFalse(Uri::isExternal('/test'));
+        self::assertFalse(Uri::isExternal('/foo/bar'));
+        self::assertTrue(Uri::isExternal('http://localhost/test'));
+        self::assertTrue(Uri::isExternal('http://google.it/test'));
     }
 
-    public function testBuildUrl()
+    public function testBuildUrl(): void
     {
         $parsed_url = [
             'scheme' => 'http',
@@ -1107,7 +1107,7 @@ class UriTest extends \Codeception\TestCase\Test
             'port'   => 8080,
         ];
 
-        $this->assertSame('http://localhost:8080', Uri::buildUrl($parsed_url));
+        self::assertSame('http://localhost:8080', Uri::buildUrl($parsed_url));
 
         $parsed_url = [
             'scheme'   => 'http',
@@ -1120,32 +1120,32 @@ class UriTest extends \Codeception\TestCase\Test
             'fragment' => 'xxx',
         ];
 
-        $this->assertSame('http://foo:bar@localhost:8080/test?x=2#xxx', Uri::buildUrl($parsed_url));
+        self::assertSame('http://foo:bar@localhost:8080/test?x=2#xxx', Uri::buildUrl($parsed_url));
 
         /** @var Uri $uri */
         $uri = Grav::instance()['uri'];
 
         $uri->initializeWithUrlAndRootPath('https://testing.dev/subdir/path1/path2/file.html', '/subdir')->init();
-        $this->assertSame('https://testing.dev/subdir/path1/path2/file.html', Uri::buildUrl($uri->toArray(true)));
+        self::assertSame('https://testing.dev/subdir/path1/path2/file.html', Uri::buildUrl($uri->toArray(true)));
 
         $uri->initializeWithUrlAndRootPath('https://testing.dev/subdir/path1/path2/file.foo', '/subdir')->init();
-        $this->assertSame('https://testing.dev/subdir/path1/path2/file.foo', Uri::buildUrl($uri->toArray(true)));
+        self::assertSame('https://testing.dev/subdir/path1/path2/file.foo', Uri::buildUrl($uri->toArray(true)));
 
         $uri->initializeWithUrlAndRootPath('https://testing.dev/subdir/path1/path2/file.html', '/subdir/path1')->init();
-        $this->assertSame('https://testing.dev/subdir/path1/path2/file.html', Uri::buildUrl($uri->toArray(true)));
+        self::assertSame('https://testing.dev/subdir/path1/path2/file.html', Uri::buildUrl($uri->toArray(true)));
 
         $uri->initializeWithUrlAndRootPath('https://testing.dev/subdir/path1/path2/file.html/foo:blah/bang:boom', '/subdir')->init();
-        $this->assertSame('https://testing.dev/subdir/path1/path2/file.html/foo:blah/bang:boom', Uri::buildUrl($uri->toArray(true)));
+        self::assertSame('https://testing.dev/subdir/path1/path2/file.html/foo:blah/bang:boom', Uri::buildUrl($uri->toArray(true)));
 
         $uri->initializeWithUrlAndRootPath('https://testing.dev/subdir/path1/path2/file.html/foo:blah/bang:boom?fig=something', '/subdir')->init();
-        $this->assertSame('https://testing.dev/subdir/path1/path2/file.html/foo:blah/bang:boom?fig=something', Uri::buildUrl($uri->toArray(true)));
+        self::assertSame('https://testing.dev/subdir/path1/path2/file.html/foo:blah/bang:boom?fig=something', Uri::buildUrl($uri->toArray(true)));
     }
 
-    public function testConvertUrl()
+    public function testConvertUrl(): void
     {
     }
 
-    public function testAddNonce()
+    public function testAddNonce(): void
     {
         $this->runTestSet($this->tests, 'addNonce');
     }
diff --git a/tests/unit/Grav/Common/UtilsTest.php b/tests/unit/Grav/Common/UtilsTest.php
index adce03edd..d396a2c3b 100644
--- a/tests/unit/Grav/Common/UtilsTest.php
+++ b/tests/unit/Grav/Common/UtilsTest.php
@@ -16,113 +16,113 @@ class UtilsTest extends \Codeception\TestCase\Test
     /** @var Uri $uri */
     protected $uri;
 
-    protected function _before()
+    protected function _before(): void
     {
         $grav = Fixtures::get('grav');
         $this->grav = $grav();
         $this->uri = $this->grav['uri'];
     }
 
-    protected function _after()
+    protected function _after(): void
     {
     }
 
-    public function testStartsWith()
+    public function testStartsWith(): void
     {
-        $this->assertTrue(Utils::startsWith('english', 'en'));
-        $this->assertTrue(Utils::startsWith('English', 'En'));
-        $this->assertTrue(Utils::startsWith('ENGLISH', 'EN'));
-        $this->assertTrue(Utils::startsWith(
+        self::assertTrue(Utils::startsWith('english', 'en'));
+        self::assertTrue(Utils::startsWith('English', 'En'));
+        self::assertTrue(Utils::startsWith('ENGLISH', 'EN'));
+        self::assertTrue(Utils::startsWith(
             'ENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISH',
             'EN'
         ));
 
-        $this->assertFalse(Utils::startsWith('english', 'En'));
-        $this->assertFalse(Utils::startsWith('English', 'EN'));
-        $this->assertFalse(Utils::startsWith('ENGLISH', 'en'));
-        $this->assertFalse(Utils::startsWith(
+        self::assertFalse(Utils::startsWith('english', 'En'));
+        self::assertFalse(Utils::startsWith('English', 'EN'));
+        self::assertFalse(Utils::startsWith('ENGLISH', 'en'));
+        self::assertFalse(Utils::startsWith(
             'ENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISH',
             'e'
         ));
 
-        $this->assertTrue(Utils::startsWith('english', 'En', false));
-        $this->assertTrue(Utils::startsWith('English', 'EN', false));
-        $this->assertTrue(Utils::startsWith('ENGLISH', 'en', false));
-        $this->assertTrue(Utils::startsWith(
+        self::assertTrue(Utils::startsWith('english', 'En', false));
+        self::assertTrue(Utils::startsWith('English', 'EN', false));
+        self::assertTrue(Utils::startsWith('ENGLISH', 'en', false));
+        self::assertTrue(Utils::startsWith(
             'ENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISH',
             'e',
             false
         ));
     }
 
-    public function testEndsWith()
+    public function testEndsWith(): void
     {
-        $this->assertTrue(Utils::endsWith('english', 'sh'));
-        $this->assertTrue(Utils::endsWith('EngliSh', 'Sh'));
-        $this->assertTrue(Utils::endsWith('ENGLISH', 'SH'));
-        $this->assertTrue(Utils::endsWith(
+        self::assertTrue(Utils::endsWith('english', 'sh'));
+        self::assertTrue(Utils::endsWith('EngliSh', 'Sh'));
+        self::assertTrue(Utils::endsWith('ENGLISH', 'SH'));
+        self::assertTrue(Utils::endsWith(
             'ENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISH',
             'ENGLISH'
         ));
 
-        $this->assertFalse(Utils::endsWith('english', 'de'));
-        $this->assertFalse(Utils::endsWith('EngliSh', 'sh'));
-        $this->assertFalse(Utils::endsWith('ENGLISH', 'Sh'));
-        $this->assertFalse(Utils::endsWith(
+        self::assertFalse(Utils::endsWith('english', 'de'));
+        self::assertFalse(Utils::endsWith('EngliSh', 'sh'));
+        self::assertFalse(Utils::endsWith('ENGLISH', 'Sh'));
+        self::assertFalse(Utils::endsWith(
             'ENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISH',
             'DEUSTCH'
         ));
 
-        $this->assertTrue(Utils::endsWith('english', 'SH', false));
-        $this->assertTrue(Utils::endsWith('EngliSh', 'sH', false));
-        $this->assertTrue(Utils::endsWith('ENGLISH', 'sh', false));
-        $this->assertTrue(Utils::endsWith(
+        self::assertTrue(Utils::endsWith('english', 'SH', false));
+        self::assertTrue(Utils::endsWith('EngliSh', 'sH', false));
+        self::assertTrue(Utils::endsWith('ENGLISH', 'sh', false));
+        self::assertTrue(Utils::endsWith(
             'ENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISH',
             'english',
             false
         ));
     }
 
-    public function testContains()
+    public function testContains(): void
     {
-        $this->assertTrue(Utils::contains('english', 'nglis'));
-        $this->assertTrue(Utils::contains('EngliSh', 'gliSh'));
-        $this->assertTrue(Utils::contains('ENGLISH', 'ENGLI'));
-        $this->assertTrue(Utils::contains(
+        self::assertTrue(Utils::contains('english', 'nglis'));
+        self::assertTrue(Utils::contains('EngliSh', 'gliSh'));
+        self::assertTrue(Utils::contains('ENGLISH', 'ENGLI'));
+        self::assertTrue(Utils::contains(
             'ENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISH',
             'ENGLISH'
         ));
 
-        $this->assertFalse(Utils::contains('EngliSh', 'GLI'));
-        $this->assertFalse(Utils::contains('EngliSh', 'English'));
-        $this->assertFalse(Utils::contains('ENGLISH', 'SCH'));
-        $this->assertFalse(Utils::contains(
+        self::assertFalse(Utils::contains('EngliSh', 'GLI'));
+        self::assertFalse(Utils::contains('EngliSh', 'English'));
+        self::assertFalse(Utils::contains('ENGLISH', 'SCH'));
+        self::assertFalse(Utils::contains(
             'ENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISH',
             'DEUSTCH'
         ));
 
-        $this->assertTrue(Utils::contains('EngliSh', 'GLI', false));
-        $this->assertTrue(Utils::contains('EngliSh', 'ENGLISH', false));
-        $this->assertTrue(Utils::contains('ENGLISH', 'ish', false));
-        $this->assertTrue(Utils::contains(
+        self::assertTrue(Utils::contains('EngliSh', 'GLI', false));
+        self::assertTrue(Utils::contains('EngliSh', 'ENGLISH', false));
+        self::assertTrue(Utils::contains('ENGLISH', 'ish', false));
+        self::assertTrue(Utils::contains(
             'ENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISHENGLISH',
             'english',
             false
         ));
     }
 
-    public function testSubstrToString()
+    public function testSubstrToString(): void
     {
-        $this->assertEquals('en', Utils::substrToString('english', 'glish'));
-        $this->assertEquals('english', Utils::substrToString('english', 'test'));
-        $this->assertNotEquals('en', Utils::substrToString('english', 'lish'));
+        self::assertEquals('en', Utils::substrToString('english', 'glish'));
+        self::assertEquals('english', Utils::substrToString('english', 'test'));
+        self::assertNotEquals('en', Utils::substrToString('english', 'lish'));
 
-        $this->assertEquals('en', Utils::substrToString('english', 'GLISH', false));
-        $this->assertEquals('english', Utils::substrToString('english', 'TEST', false));
-        $this->assertNotEquals('en', Utils::substrToString('english', 'LISH', false));
+        self::assertEquals('en', Utils::substrToString('english', 'GLISH', false));
+        self::assertEquals('english', Utils::substrToString('english', 'TEST', false));
+        self::assertNotEquals('en', Utils::substrToString('english', 'LISH', false));
     }
 
-    public function testMergeObjects()
+    public function testMergeObjects(): void
     {
         $obj1 = new stdClass();
         $obj1->test1 = 'x';
@@ -131,150 +131,150 @@ class UtilsTest extends \Codeception\TestCase\Test
 
         $objMerged = Utils::mergeObjects($obj1, $obj2);
 
-        $this->assertObjectHasAttribute('test1', $objMerged);
-        $this->assertObjectHasAttribute('test2', $objMerged);
+        self::assertObjectHasAttribute('test1', $objMerged);
+        self::assertObjectHasAttribute('test2', $objMerged);
     }
 
-    public function testDateFormats()
+    public function testDateFormats(): void
     {
         $dateFormats = Utils::dateFormats();
-        $this->assertIsArray($dateFormats);
-        $this->assertContainsOnly('string', $dateFormats);
+        self::assertIsArray($dateFormats);
+        self::assertContainsOnly('string', $dateFormats);
 
         $default_format = $this->grav['config']->get('system.pages.dateformat.default');
 
         if ($default_format !== null) {
-            $this->assertArrayHasKey($default_format, $dateFormats);
+            self::assertArrayHasKey($default_format, $dateFormats);
         }
     }
 
-    public function testTruncate()
+    public function testTruncate(): void
     {
-        $this->assertEquals('engli' . '&hellip;', Utils::truncate('english', 5));
-        $this->assertEquals('english', Utils::truncate('english'));
-        $this->assertEquals('This is a string to truncate', Utils::truncate('This is a string to truncate'));
-        $this->assertEquals('Th' . '&hellip;', Utils::truncate('This is a string to truncate', 2));
-        $this->assertEquals('engli' . '...', Utils::truncate('english', 5, true, " ", "..."));
-        $this->assertEquals('english', Utils::truncate('english'));
-        $this->assertEquals('This is a string to truncate', Utils::truncate('This is a string to truncate'));
-        $this->assertEquals('This' . '&hellip;', Utils::truncate('This is a string to truncate', 3, true));
-        $this->assertEquals('<input' . '&hellip;', Utils::truncate('<input type="file" id="file" multiple />', 6, true));
+        self::assertEquals('engli' . '&hellip;', Utils::truncate('english', 5));
+        self::assertEquals('english', Utils::truncate('english'));
+        self::assertEquals('This is a string to truncate', Utils::truncate('This is a string to truncate'));
+        self::assertEquals('Th' . '&hellip;', Utils::truncate('This is a string to truncate', 2));
+        self::assertEquals('engli' . '...', Utils::truncate('english', 5, true, " ", "..."));
+        self::assertEquals('english', Utils::truncate('english'));
+        self::assertEquals('This is a string to truncate', Utils::truncate('This is a string to truncate'));
+        self::assertEquals('This' . '&hellip;', Utils::truncate('This is a string to truncate', 3, true));
+        self::assertEquals('<input' . '&hellip;', Utils::truncate('<input type="file" id="file" multiple />', 6, true));
     }
 
-    public function testSafeTruncate()
+    public function testSafeTruncate(): void
     {
-        $this->assertEquals('This' . '&hellip;', Utils::safeTruncate('This is a string to truncate', 1));
-        $this->assertEquals('This' . '&hellip;', Utils::safeTruncate('This is a string to truncate', 4));
-        $this->assertEquals('This is' . '&hellip;', Utils::safeTruncate('This is a string to truncate', 5));
+        self::assertEquals('This' . '&hellip;', Utils::safeTruncate('This is a string to truncate', 1));
+        self::assertEquals('This' . '&hellip;', Utils::safeTruncate('This is a string to truncate', 4));
+        self::assertEquals('This is' . '&hellip;', Utils::safeTruncate('This is a string to truncate', 5));
     }
 
-    public function testTruncateHtml()
+    public function testTruncateHtml(): void
     {
-        $this->assertEquals('T...', Utils::truncateHtml('This is a string to truncate', 1));
-        $this->assertEquals('This is...', Utils::truncateHtml('This is a string to truncate', 7));
-        $this->assertEquals('<p>T...</p>', Utils::truncateHtml('<p>This is a string to truncate</p>', 1));
-        $this->assertEquals('<p>This...</p>', Utils::truncateHtml('<p>This is a string to truncate</p>', 4));
-        $this->assertEquals('<p>This is a...</p>', Utils::truncateHtml('<p>This is a string to truncate</p>', 10));
-        $this->assertEquals('<p>This is a string to truncate</p>', Utils::truncateHtml('<p>This is a string to truncate</p>', 100));
-        $this->assertEquals('<input type="file" id="file" multiple />', Utils::truncateHtml('<input type="file" id="file" multiple />', 6));
-        $this->assertEquals('<ol><li>item 1 <i>so...</i></li></ol>', Utils::truncateHtml('<ol><li>item 1 <i>something</i></li><li>item 2 <strong>bold</strong></li></ol>', 10));
-        $this->assertEquals("<p>This is a string.</p>\n<p>It splits two lines.</p>", Utils::truncateHtml("<p>This is a string.</p>\n<p>It splits two lines.</p>", 100));
+        self::assertEquals('T...', Utils::truncateHtml('This is a string to truncate', 1));
+        self::assertEquals('This is...', Utils::truncateHtml('This is a string to truncate', 7));
+        self::assertEquals('<p>T...</p>', Utils::truncateHtml('<p>This is a string to truncate</p>', 1));
+        self::assertEquals('<p>This...</p>', Utils::truncateHtml('<p>This is a string to truncate</p>', 4));
+        self::assertEquals('<p>This is a...</p>', Utils::truncateHtml('<p>This is a string to truncate</p>', 10));
+        self::assertEquals('<p>This is a string to truncate</p>', Utils::truncateHtml('<p>This is a string to truncate</p>', 100));
+        self::assertEquals('<input type="file" id="file" multiple />', Utils::truncateHtml('<input type="file" id="file" multiple />', 6));
+        self::assertEquals('<ol><li>item 1 <i>so...</i></li></ol>', Utils::truncateHtml('<ol><li>item 1 <i>something</i></li><li>item 2 <strong>bold</strong></li></ol>', 10));
+        self::assertEquals("<p>This is a string.</p>\n<p>It splits two lines.</p>", Utils::truncateHtml("<p>This is a string.</p>\n<p>It splits two lines.</p>", 100));
     }
 
-    public function testSafeTruncateHtml()
+    public function testSafeTruncateHtml(): void
     {
-        $this->assertEquals('This...', Utils::safeTruncateHtml('This is a string to truncate', 1));
-        $this->assertEquals('This is a...', Utils::safeTruncateHtml('This is a string to truncate', 3));
-        $this->assertEquals('<p>This...</p>', Utils::safeTruncateHtml('<p>This is a string to truncate</p>', 1));
-        $this->assertEquals('<p>This is...</p>', Utils::safeTruncateHtml('<p>This is a string to truncate</p>', 2));
-        $this->assertEquals('<p>This is a string to...</p>', Utils::safeTruncateHtml('<p>This is a string to truncate</p>', 5));
-        $this->assertEquals('<p>This is a string to truncate</p>', Utils::safeTruncateHtml('<p>This is a string to truncate</p>', 20));
-        $this->assertEquals('<input type="file" id="file" multiple />', Utils::safeTruncateHtml('<input type="file" id="file" multiple />', 6));
-        $this->assertEquals('<ol><li>item 1 <i>something</i></li><li>item 2...</li></ol>', Utils::safeTruncateHtml('<ol><li>item 1 <i>something</i></li><li>item 2 <strong>bold</strong></li></ol>', 5));
+        self::assertEquals('This...', Utils::safeTruncateHtml('This is a string to truncate', 1));
+        self::assertEquals('This is a...', Utils::safeTruncateHtml('This is a string to truncate', 3));
+        self::assertEquals('<p>This...</p>', Utils::safeTruncateHtml('<p>This is a string to truncate</p>', 1));
+        self::assertEquals('<p>This is...</p>', Utils::safeTruncateHtml('<p>This is a string to truncate</p>', 2));
+        self::assertEquals('<p>This is a string to...</p>', Utils::safeTruncateHtml('<p>This is a string to truncate</p>', 5));
+        self::assertEquals('<p>This is a string to truncate</p>', Utils::safeTruncateHtml('<p>This is a string to truncate</p>', 20));
+        self::assertEquals('<input type="file" id="file" multiple />', Utils::safeTruncateHtml('<input type="file" id="file" multiple />', 6));
+        self::assertEquals('<ol><li>item 1 <i>something</i></li><li>item 2...</li></ol>', Utils::safeTruncateHtml('<ol><li>item 1 <i>something</i></li><li>item 2 <strong>bold</strong></li></ol>', 5));
     }
 
-    public function testGenerateRandomString()
+    public function testGenerateRandomString(): void
     {
-        $this->assertNotEquals(Utils::generateRandomString(), Utils::generateRandomString());
-        $this->assertNotEquals(Utils::generateRandomString(20), Utils::generateRandomString(20));
+        self::assertNotEquals(Utils::generateRandomString(), Utils::generateRandomString());
+        self::assertNotEquals(Utils::generateRandomString(20), Utils::generateRandomString(20));
     }
 
-    public function download()
+    public function download(): void
     {
     }
 
-    public function testGetMimeByExtension()
+    public function testGetMimeByExtension(): void
     {
-        $this->assertEquals('application/octet-stream', Utils::getMimeByExtension(''));
-        $this->assertEquals('text/html', Utils::getMimeByExtension('html'));
-        $this->assertEquals('application/json', Utils::getMimeByExtension('json'));
-        $this->assertEquals('application/atom+xml', Utils::getMimeByExtension('atom'));
-        $this->assertEquals('application/rss+xml', Utils::getMimeByExtension('rss'));
-        $this->assertEquals('image/jpeg', Utils::getMimeByExtension('jpg'));
-        $this->assertEquals('image/png', Utils::getMimeByExtension('png'));
-        $this->assertEquals('text/plain', Utils::getMimeByExtension('txt'));
-        $this->assertEquals('application/msword', Utils::getMimeByExtension('doc'));
-        $this->assertEquals('application/octet-stream', Utils::getMimeByExtension('foo'));
-        $this->assertEquals('foo/bar', Utils::getMimeByExtension('foo', 'foo/bar'));
-        $this->assertEquals('text/html', Utils::getMimeByExtension('foo', 'text/html'));
+        self::assertEquals('application/octet-stream', Utils::getMimeByExtension(''));
+        self::assertEquals('text/html', Utils::getMimeByExtension('html'));
+        self::assertEquals('application/json', Utils::getMimeByExtension('json'));
+        self::assertEquals('application/atom+xml', Utils::getMimeByExtension('atom'));
+        self::assertEquals('application/rss+xml', Utils::getMimeByExtension('rss'));
+        self::assertEquals('image/jpeg', Utils::getMimeByExtension('jpg'));
+        self::assertEquals('image/png', Utils::getMimeByExtension('png'));
+        self::assertEquals('text/plain', Utils::getMimeByExtension('txt'));
+        self::assertEquals('application/msword', Utils::getMimeByExtension('doc'));
+        self::assertEquals('application/octet-stream', Utils::getMimeByExtension('foo'));
+        self::assertEquals('foo/bar', Utils::getMimeByExtension('foo', 'foo/bar'));
+        self::assertEquals('text/html', Utils::getMimeByExtension('foo', 'text/html'));
     }
 
-    public function testGetExtensionByMime()
+    public function testGetExtensionByMime(): void
     {
-        $this->assertEquals('html', Utils::getExtensionByMime('*/*'));
-        $this->assertEquals('html', Utils::getExtensionByMime('text/*'));
-        $this->assertEquals('html', Utils::getExtensionByMime('text/html'));
-        $this->assertEquals('json', Utils::getExtensionByMime('application/json'));
-        $this->assertEquals('atom', Utils::getExtensionByMime('application/atom+xml'));
-        $this->assertEquals('rss', Utils::getExtensionByMime('application/rss+xml'));
-        $this->assertEquals('jpg', Utils::getExtensionByMime('image/jpeg'));
-        $this->assertEquals('png', Utils::getExtensionByMime('image/png'));
-        $this->assertEquals('txt', Utils::getExtensionByMime('text/plain'));
-        $this->assertEquals('doc', Utils::getExtensionByMime('application/msword'));
-        $this->assertEquals('html', Utils::getExtensionByMime('foo/bar'));
-        $this->assertEquals('baz', Utils::getExtensionByMime('foo/bar', 'baz'));
+        self::assertEquals('html', Utils::getExtensionByMime('*/*'));
+        self::assertEquals('html', Utils::getExtensionByMime('text/*'));
+        self::assertEquals('html', Utils::getExtensionByMime('text/html'));
+        self::assertEquals('json', Utils::getExtensionByMime('application/json'));
+        self::assertEquals('atom', Utils::getExtensionByMime('application/atom+xml'));
+        self::assertEquals('rss', Utils::getExtensionByMime('application/rss+xml'));
+        self::assertEquals('jpg', Utils::getExtensionByMime('image/jpeg'));
+        self::assertEquals('png', Utils::getExtensionByMime('image/png'));
+        self::assertEquals('txt', Utils::getExtensionByMime('text/plain'));
+        self::assertEquals('doc', Utils::getExtensionByMime('application/msword'));
+        self::assertEquals('html', Utils::getExtensionByMime('foo/bar'));
+        self::assertEquals('baz', Utils::getExtensionByMime('foo/bar', 'baz'));
     }
 
-    public function testNormalizePath()
+    public function testNormalizePath(): void
     {
-        $this->assertEquals('/test', Utils::normalizePath('/test'));
-        $this->assertEquals('test', Utils::normalizePath('test'));
-        $this->assertEquals('test', Utils::normalizePath('../test'));
-        $this->assertEquals('/test', Utils::normalizePath('/../test'));
-        $this->assertEquals('/test2', Utils::normalizePath('/test/../test2'));
-        $this->assertEquals('/test3', Utils::normalizePath('/test/../test2/../test3'));
+        self::assertEquals('/test', Utils::normalizePath('/test'));
+        self::assertEquals('test', Utils::normalizePath('test'));
+        self::assertEquals('test', Utils::normalizePath('../test'));
+        self::assertEquals('/test', Utils::normalizePath('/../test'));
+        self::assertEquals('/test2', Utils::normalizePath('/test/../test2'));
+        self::assertEquals('/test3', Utils::normalizePath('/test/../test2/../test3'));
 
-        $this->assertEquals('//cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css', Utils::normalizePath('//cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css'));
-        $this->assertEquals('//use.fontawesome.com/releases/v5.8.1/css/all.css', Utils::normalizePath('//use.fontawesome.com/releases/v5.8.1/css/all.css'));
-        $this->assertEquals('//use.fontawesome.com/releases/v5.8.1/webfonts/fa-brands-400.eot', Utils::normalizePath('//use.fontawesome.com/releases/v5.8.1/css/../webfonts/fa-brands-400.eot'));
+        self::assertEquals('//cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css', Utils::normalizePath('//cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css'));
+        self::assertEquals('//use.fontawesome.com/releases/v5.8.1/css/all.css', Utils::normalizePath('//use.fontawesome.com/releases/v5.8.1/css/all.css'));
+        self::assertEquals('//use.fontawesome.com/releases/v5.8.1/webfonts/fa-brands-400.eot', Utils::normalizePath('//use.fontawesome.com/releases/v5.8.1/css/../webfonts/fa-brands-400.eot'));
 
-        $this->assertEquals('http://cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css', Utils::normalizePath('http://cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css'));
-        $this->assertEquals('http://use.fontawesome.com/releases/v5.8.1/css/all.css', Utils::normalizePath('http://use.fontawesome.com/releases/v5.8.1/css/all.css'));
-        $this->assertEquals('http://use.fontawesome.com/releases/v5.8.1/webfonts/fa-brands-400.eot', Utils::normalizePath('http://use.fontawesome.com/releases/v5.8.1/css/../webfonts/fa-brands-400.eot'));
+        self::assertEquals('http://cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css', Utils::normalizePath('http://cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css'));
+        self::assertEquals('http://use.fontawesome.com/releases/v5.8.1/css/all.css', Utils::normalizePath('http://use.fontawesome.com/releases/v5.8.1/css/all.css'));
+        self::assertEquals('http://use.fontawesome.com/releases/v5.8.1/webfonts/fa-brands-400.eot', Utils::normalizePath('http://use.fontawesome.com/releases/v5.8.1/css/../webfonts/fa-brands-400.eot'));
 
-        $this->assertEquals('https://cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css', Utils::normalizePath('https://cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css'));
-        $this->assertEquals('https://use.fontawesome.com/releases/v5.8.1/css/all.css', Utils::normalizePath('https://use.fontawesome.com/releases/v5.8.1/css/all.css'));
-        $this->assertEquals('https://use.fontawesome.com/releases/v5.8.1/webfonts/fa-brands-400.eot', Utils::normalizePath('https://use.fontawesome.com/releases/v5.8.1/css/../webfonts/fa-brands-400.eot'));
+        self::assertEquals('https://cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css', Utils::normalizePath('https://cdnjs.cloudflare.com/ajax/libs/Leaflet.awesome-markers/2.0.2/leaflet.awesome-markers.css'));
+        self::assertEquals('https://use.fontawesome.com/releases/v5.8.1/css/all.css', Utils::normalizePath('https://use.fontawesome.com/releases/v5.8.1/css/all.css'));
+        self::assertEquals('https://use.fontawesome.com/releases/v5.8.1/webfonts/fa-brands-400.eot', Utils::normalizePath('https://use.fontawesome.com/releases/v5.8.1/css/../webfonts/fa-brands-400.eot'));
     }
 
-    public function testIsFunctionDisabled()
+    public function testIsFunctionDisabled(): void
     {
         $disabledFunctions = explode(',', ini_get('disable_functions'));
 
         if ($disabledFunctions[0]) {
-            $this->assertEquals(Utils::isFunctionDisabled($disabledFunctions[0]), true);
+            self::assertEquals(Utils::isFunctionDisabled($disabledFunctions[0]), true);
         }
     }
 
-    public function testTimezones()
+    public function testTimezones(): void
     {
         $timezones = Utils::timezones();
 
-        $this->assertIsArray($timezones);
-        $this->assertContainsOnly('string', $timezones);
+        self::assertIsArray($timezones);
+        self::assertContainsOnly('string', $timezones);
     }
 
-    public function testArrayFilterRecursive()
+    public function testArrayFilterRecursive(): void
     {
         $array = [
             'test'  => '',
@@ -285,13 +285,13 @@ class UtilsTest extends \Codeception\TestCase\Test
             return !(is_null($v) || $v === '');
         });
 
-        $this->assertContainsOnly('string', $array);
-        $this->assertArrayNotHasKey('test', $array);
-        $this->assertArrayHasKey('test2', $array);
-        $this->assertEquals('test2', $array['test2']);
+        self::assertContainsOnly('string', $array);
+        self::assertArrayNotHasKey('test', $array);
+        self::assertArrayHasKey('test2', $array);
+        self::assertEquals('test2', $array['test2']);
     }
 
-    public function testPathPrefixedByLangCode()
+    public function testPathPrefixedByLangCode(): void
     {
         $languagesEnabled = $this->grav['config']->get('system.languages.supported', []);
         $arrayOfLanguages = ['en', 'de', 'it', 'es', 'dk', 'el'];
@@ -299,24 +299,24 @@ class UtilsTest extends \Codeception\TestCase\Test
         $oneLanguageNotEnabled = reset($languagesNotEnabled);
 
         if (count($languagesEnabled)) {
-            $this->assertTrue(Utils::pathPrefixedByLangCode('/' . $languagesEnabled[0] . '/test'));
+            self::assertTrue(Utils::pathPrefixedByLangCode('/' . $languagesEnabled[0] . '/test'));
         }
 
-        $this->assertFalse(Utils::pathPrefixedByLangCode('/' . $oneLanguageNotEnabled . '/test'));
-        $this->assertFalse(Utils::pathPrefixedByLangCode('/test'));
-        $this->assertFalse(Utils::pathPrefixedByLangCode('/xx'));
-        $this->assertFalse(Utils::pathPrefixedByLangCode('/xx/'));
-        $this->assertFalse(Utils::pathPrefixedByLangCode('/'));
+        self::assertFalse(Utils::pathPrefixedByLangCode('/' . $oneLanguageNotEnabled . '/test'));
+        self::assertFalse(Utils::pathPrefixedByLangCode('/test'));
+        self::assertFalse(Utils::pathPrefixedByLangCode('/xx'));
+        self::assertFalse(Utils::pathPrefixedByLangCode('/xx/'));
+        self::assertFalse(Utils::pathPrefixedByLangCode('/'));
     }
 
-    public function testDate2timestamp()
+    public function testDate2timestamp(): void
     {
         $timestamp = strtotime('10 September 2000');
-        $this->assertSame($timestamp, Utils::date2timestamp('10 September 2000'));
-        $this->assertSame($timestamp, Utils::date2timestamp('2000-09-10 00:00:00'));
+        self::assertSame($timestamp, Utils::date2timestamp('10 September 2000'));
+        self::assertSame($timestamp, Utils::date2timestamp('2000-09-10 00:00:00'));
     }
 
-    public function testResolve()
+    public function testResolve(): void
     {
         $array = [
             'test' => [
@@ -324,10 +324,10 @@ class UtilsTest extends \Codeception\TestCase\Test
             ]
         ];
 
-        $this->assertEquals('test2Value', Utils::resolve($array, 'test.test2'));
+        self::assertEquals('test2Value', Utils::resolve($array, 'test.test2'));
     }
 
-    public function testGetDotNotation()
+    public function testGetDotNotation(): void
     {
         $array = [
             'test' => [
@@ -338,12 +338,12 @@ class UtilsTest extends \Codeception\TestCase\Test
             ]
         ];
 
-        $this->assertEquals('test2Value', Utils::getDotNotation($array, 'test.test2'));
-        $this->assertEquals('test4Value', Utils::getDotNotation($array, 'test.test3.test4'));
-        $this->assertEquals('defaultValue', Utils::getDotNotation($array, 'test.non_existent', 'defaultValue'));
+        self::assertEquals('test2Value', Utils::getDotNotation($array, 'test.test2'));
+        self::assertEquals('test4Value', Utils::getDotNotation($array, 'test.test3.test4'));
+        self::assertEquals('defaultValue', Utils::getDotNotation($array, 'test.non_existent', 'defaultValue'));
     }
 
-    public function testSetDotNotation()
+    public function testSetDotNotation(): void
     {
         $array = [
             'test' => [
@@ -359,201 +359,201 @@ class UtilsTest extends \Codeception\TestCase\Test
         ];
 
         Utils::setDotNotation($array, 'test.test3.test4', $new);
-        $this->assertEquals('test1Value', $array['test']['test3']['test4']['test1']);
+        self::assertEquals('test1Value', $array['test']['test3']['test4']['test1']);
     }
 
-    public function testIsPositive()
+    public function testIsPositive(): void
     {
-        $this->assertTrue(Utils::isPositive(true));
-        $this->assertTrue(Utils::isPositive(1));
-        $this->assertTrue(Utils::isPositive('1'));
-        $this->assertTrue(Utils::isPositive('yes'));
-        $this->assertTrue(Utils::isPositive('on'));
-        $this->assertTrue(Utils::isPositive('true'));
-        $this->assertFalse(Utils::isPositive(false));
-        $this->assertFalse(Utils::isPositive(0));
-        $this->assertFalse(Utils::isPositive('0'));
-        $this->assertFalse(Utils::isPositive('no'));
-        $this->assertFalse(Utils::isPositive('off'));
-        $this->assertFalse(Utils::isPositive('false'));
-        $this->assertFalse(Utils::isPositive('some'));
-        $this->assertFalse(Utils::isPositive(2));
+        self::assertTrue(Utils::isPositive(true));
+        self::assertTrue(Utils::isPositive(1));
+        self::assertTrue(Utils::isPositive('1'));
+        self::assertTrue(Utils::isPositive('yes'));
+        self::assertTrue(Utils::isPositive('on'));
+        self::assertTrue(Utils::isPositive('true'));
+        self::assertFalse(Utils::isPositive(false));
+        self::assertFalse(Utils::isPositive(0));
+        self::assertFalse(Utils::isPositive('0'));
+        self::assertFalse(Utils::isPositive('no'));
+        self::assertFalse(Utils::isPositive('off'));
+        self::assertFalse(Utils::isPositive('false'));
+        self::assertFalse(Utils::isPositive('some'));
+        self::assertFalse(Utils::isPositive(2));
     }
 
-    public function testGetNonce()
+    public function testGetNonce(): void
     {
-        $this->assertIsString(Utils::getNonce('test-action'));
-        $this->assertIsString(Utils::getNonce('test-action', true));
-        $this->assertSame(Utils::getNonce('test-action'), Utils::getNonce('test-action'));
-        $this->assertNotSame(Utils::getNonce('test-action'), Utils::getNonce('test-action2'));
+        self::assertIsString(Utils::getNonce('test-action'));
+        self::assertIsString(Utils::getNonce('test-action', true));
+        self::assertSame(Utils::getNonce('test-action'), Utils::getNonce('test-action'));
+        self::assertNotSame(Utils::getNonce('test-action'), Utils::getNonce('test-action2'));
     }
 
-    public function testVerifyNonce()
+    public function testVerifyNonce(): void
     {
-        $this->assertTrue(Utils::verifyNonce(Utils::getNonce('test-action'), 'test-action'));
+        self::assertTrue(Utils::verifyNonce(Utils::getNonce('test-action'), 'test-action'));
     }
 
-    public function testUrl()
+    public function testUrl(): void
     {
         $this->uri->initializeWithUrl('http://testing.dev/path1/path2')->init();
 
         // Fail hard
-        $this->assertSame(false, Utils::url('', true));
-        $this->assertSame(false, Utils::url(''));
-        $this->assertSame(false, Utils::url(new stdClass()));
-        $this->assertSame(false, Utils::url(['foo','bar','baz']));
-        $this->assertSame(false, Utils::url('user://does/not/exist'));
+        self::assertSame(false, Utils::url('', true));
+        self::assertSame(false, Utils::url(''));
+        self::assertSame(false, Utils::url(new stdClass()));
+        self::assertSame(false, Utils::url(['foo','bar','baz']));
+        self::assertSame(false, Utils::url('user://does/not/exist'));
 
         // Fail Gracefully
-        $this->assertSame('/', Utils::url('/', false, true));
-        $this->assertSame('/', Utils::url('', false, true));
-        $this->assertSame('/', Utils::url(new stdClass(), false, true));
-        $this->assertSame('/', Utils::url(['foo','bar','baz'], false, true));
-        $this->assertSame('/user/does/not/exist', Utils::url('user://does/not/exist', false, true));
+        self::assertSame('/', Utils::url('/', false, true));
+        self::assertSame('/', Utils::url('', false, true));
+        self::assertSame('/', Utils::url(new stdClass(), false, true));
+        self::assertSame('/', Utils::url(['foo','bar','baz'], false, true));
+        self::assertSame('/user/does/not/exist', Utils::url('user://does/not/exist', false, true));
 
         // Simple paths
-        $this->assertSame('/', Utils::url('/'));
-        $this->assertSame('/path1', Utils::url('/path1'));
-        $this->assertSame('/path1/path2', Utils::url('/path1/path2'));
-        $this->assertSame('/random/path1/path2', Utils::url('/random/path1/path2'));
-        $this->assertSame('/foobar.jpg', Utils::url('/foobar.jpg'));
-        $this->assertSame('/path1/foobar.jpg', Utils::url('/path1/foobar.jpg'));
-        $this->assertSame('/path1/path2/foobar.jpg', Utils::url('/path1/path2/foobar.jpg'));
-        $this->assertSame('/random/path1/path2/foobar.jpg', Utils::url('/random/path1/path2/foobar.jpg'));
+        self::assertSame('/', Utils::url('/'));
+        self::assertSame('/path1', Utils::url('/path1'));
+        self::assertSame('/path1/path2', Utils::url('/path1/path2'));
+        self::assertSame('/random/path1/path2', Utils::url('/random/path1/path2'));
+        self::assertSame('/foobar.jpg', Utils::url('/foobar.jpg'));
+        self::assertSame('/path1/foobar.jpg', Utils::url('/path1/foobar.jpg'));
+        self::assertSame('/path1/path2/foobar.jpg', Utils::url('/path1/path2/foobar.jpg'));
+        self::assertSame('/random/path1/path2/foobar.jpg', Utils::url('/random/path1/path2/foobar.jpg'));
 
         // Simple paths with domain
-        $this->assertSame('http://testing.dev/', Utils::url('/', true));
-        $this->assertSame('http://testing.dev/path1', Utils::url('/path1', true));
-        $this->assertSame('http://testing.dev/path1/path2', Utils::url('/path1/path2', true));
-        $this->assertSame('http://testing.dev/random/path1/path2', Utils::url('/random/path1/path2', true));
-        $this->assertSame('http://testing.dev/foobar.jpg', Utils::url('/foobar.jpg', true));
-        $this->assertSame('http://testing.dev/path1/foobar.jpg', Utils::url('/path1/foobar.jpg', true));
-        $this->assertSame('http://testing.dev/path1/path2/foobar.jpg', Utils::url('/path1/path2/foobar.jpg', true));
-        $this->assertSame('http://testing.dev/random/path1/path2/foobar.jpg', Utils::url('/random/path1/path2/foobar.jpg', true));
+        self::assertSame('http://testing.dev/', Utils::url('/', true));
+        self::assertSame('http://testing.dev/path1', Utils::url('/path1', true));
+        self::assertSame('http://testing.dev/path1/path2', Utils::url('/path1/path2', true));
+        self::assertSame('http://testing.dev/random/path1/path2', Utils::url('/random/path1/path2', true));
+        self::assertSame('http://testing.dev/foobar.jpg', Utils::url('/foobar.jpg', true));
+        self::assertSame('http://testing.dev/path1/foobar.jpg', Utils::url('/path1/foobar.jpg', true));
+        self::assertSame('http://testing.dev/path1/path2/foobar.jpg', Utils::url('/path1/path2/foobar.jpg', true));
+        self::assertSame('http://testing.dev/random/path1/path2/foobar.jpg', Utils::url('/random/path1/path2/foobar.jpg', true));
 
         // Relative paths from Grav root.
-        $this->assertSame('/subdir', Utils::url('subdir'));
-        $this->assertSame('/subdir/path1', Utils::url('subdir/path1'));
-        $this->assertSame('/subdir/path1/path2', Utils::url('subdir/path1/path2'));
-        $this->assertSame('/path1', Utils::url('path1'));
-        $this->assertSame('/path1/path2', Utils::url('path1/path2'));
-        $this->assertSame('/foobar.jpg', Utils::url('foobar.jpg'));
-        $this->assertSame('http://testing.dev/foobar.jpg', Utils::url('foobar.jpg', true));
+        self::assertSame('/subdir', Utils::url('subdir'));
+        self::assertSame('/subdir/path1', Utils::url('subdir/path1'));
+        self::assertSame('/subdir/path1/path2', Utils::url('subdir/path1/path2'));
+        self::assertSame('/path1', Utils::url('path1'));
+        self::assertSame('/path1/path2', Utils::url('path1/path2'));
+        self::assertSame('/foobar.jpg', Utils::url('foobar.jpg'));
+        self::assertSame('http://testing.dev/foobar.jpg', Utils::url('foobar.jpg', true));
 
         // Relative paths from Grav root with domain.
-        $this->assertSame('http://testing.dev/foobar.jpg', Utils::url('foobar.jpg', true));
-        $this->assertSame('http://testing.dev/foobar.jpg', Utils::url('/foobar.jpg', true));
-        $this->assertSame('http://testing.dev/path1/foobar.jpg', Utils::url('/path1/foobar.jpg', true));
+        self::assertSame('http://testing.dev/foobar.jpg', Utils::url('foobar.jpg', true));
+        self::assertSame('http://testing.dev/foobar.jpg', Utils::url('/foobar.jpg', true));
+        self::assertSame('http://testing.dev/path1/foobar.jpg', Utils::url('/path1/foobar.jpg', true));
 
         // All Non-existing streams should be treated as external URI / protocol.
-        $this->assertSame('http://domain.com/path', Utils::url('http://domain.com/path'));
-        $this->assertSame('ftp://domain.com/path', Utils::url('ftp://domain.com/path'));
-        $this->assertSame('sftp://domain.com/path', Utils::url('sftp://domain.com/path'));
-        $this->assertSame('ssh://domain.com', Utils::url('ssh://domain.com'));
-        $this->assertSame('pop://domain.com', Utils::url('pop://domain.com'));
-        $this->assertSame('foo://bar/baz', Utils::url('foo://bar/baz'));
-        $this->assertSame('foo://bar/baz', Utils::url('foo://bar/baz', true));
-        // $this->assertSame('mailto:joe@domain.com', Utils::url('mailto:joe@domain.com', true)); // FIXME <-
+        self::assertSame('http://domain.com/path', Utils::url('http://domain.com/path'));
+        self::assertSame('ftp://domain.com/path', Utils::url('ftp://domain.com/path'));
+        self::assertSame('sftp://domain.com/path', Utils::url('sftp://domain.com/path'));
+        self::assertSame('ssh://domain.com', Utils::url('ssh://domain.com'));
+        self::assertSame('pop://domain.com', Utils::url('pop://domain.com'));
+        self::assertSame('foo://bar/baz', Utils::url('foo://bar/baz'));
+        self::assertSame('foo://bar/baz', Utils::url('foo://bar/baz', true));
+        // self::assertSame('mailto:joe@domain.com', Utils::url('mailto:joe@domain.com', true)); // FIXME <-
     }
 
-    public function testUrlWithRoot()
+    public function testUrlWithRoot(): void
     {
         $this->uri->initializeWithUrlAndRootPath('http://testing.dev/subdir/path1/path2', '/subdir')->init();
 
         // Fail hard
-        $this->assertSame(false, Utils::url('', true));
-        $this->assertSame(false, Utils::url(''));
-        $this->assertSame(false, Utils::url(new stdClass()));
-        $this->assertSame(false, Utils::url(['foo','bar','baz']));
-        $this->assertSame(false, Utils::url('user://does/not/exist'));
+        self::assertSame(false, Utils::url('', true));
+        self::assertSame(false, Utils::url(''));
+        self::assertSame(false, Utils::url(new stdClass()));
+        self::assertSame(false, Utils::url(['foo','bar','baz']));
+        self::assertSame(false, Utils::url('user://does/not/exist'));
 
         // Fail Gracefully
-        $this->assertSame('/subdir/', Utils::url('/', false, true));
-        $this->assertSame('/subdir/', Utils::url('', false, true));
-        $this->assertSame('/subdir/', Utils::url(new stdClass(), false, true));
-        $this->assertSame('/subdir/', Utils::url(['foo','bar','baz'], false, true));
-        $this->assertSame('/subdir/user/does/not/exist', Utils::url('user://does/not/exist', false, true));
+        self::assertSame('/subdir/', Utils::url('/', false, true));
+        self::assertSame('/subdir/', Utils::url('', false, true));
+        self::assertSame('/subdir/', Utils::url(new stdClass(), false, true));
+        self::assertSame('/subdir/', Utils::url(['foo','bar','baz'], false, true));
+        self::assertSame('/subdir/user/does/not/exist', Utils::url('user://does/not/exist', false, true));
 
         // Simple paths
-        $this->assertSame('/subdir/', Utils::url('/'));
-        $this->assertSame('/subdir/path1', Utils::url('/path1'));
-        $this->assertSame('/subdir/path1/path2', Utils::url('/path1/path2'));
-        $this->assertSame('/subdir/random/path1/path2', Utils::url('/random/path1/path2'));
-        $this->assertSame('/subdir/foobar.jpg', Utils::url('/foobar.jpg'));
-        $this->assertSame('/subdir/path1/foobar.jpg', Utils::url('/path1/foobar.jpg'));
-        $this->assertSame('/subdir/path1/path2/foobar.jpg', Utils::url('/path1/path2/foobar.jpg'));
-        $this->assertSame('/subdir/random/path1/path2/foobar.jpg', Utils::url('/random/path1/path2/foobar.jpg'));
+        self::assertSame('/subdir/', Utils::url('/'));
+        self::assertSame('/subdir/path1', Utils::url('/path1'));
+        self::assertSame('/subdir/path1/path2', Utils::url('/path1/path2'));
+        self::assertSame('/subdir/random/path1/path2', Utils::url('/random/path1/path2'));
+        self::assertSame('/subdir/foobar.jpg', Utils::url('/foobar.jpg'));
+        self::assertSame('/subdir/path1/foobar.jpg', Utils::url('/path1/foobar.jpg'));
+        self::assertSame('/subdir/path1/path2/foobar.jpg', Utils::url('/path1/path2/foobar.jpg'));
+        self::assertSame('/subdir/random/path1/path2/foobar.jpg', Utils::url('/random/path1/path2/foobar.jpg'));
 
         // Simple paths with domain
-        $this->assertSame('http://testing.dev/subdir/', Utils::url('/', true));
-        $this->assertSame('http://testing.dev/subdir/path1', Utils::url('/path1', true));
-        $this->assertSame('http://testing.dev/subdir/path1/path2', Utils::url('/path1/path2', true));
-        $this->assertSame('http://testing.dev/subdir/random/path1/path2', Utils::url('/random/path1/path2', true));
-        $this->assertSame('http://testing.dev/subdir/foobar.jpg', Utils::url('/foobar.jpg', true));
-        $this->assertSame('http://testing.dev/subdir/path1/foobar.jpg', Utils::url('/path1/foobar.jpg', true));
-        $this->assertSame('http://testing.dev/subdir/path1/path2/foobar.jpg', Utils::url('/path1/path2/foobar.jpg', true));
-        $this->assertSame('http://testing.dev/subdir/random/path1/path2/foobar.jpg', Utils::url('/random/path1/path2/foobar.jpg', true));
+        self::assertSame('http://testing.dev/subdir/', Utils::url('/', true));
+        self::assertSame('http://testing.dev/subdir/path1', Utils::url('/path1', true));
+        self::assertSame('http://testing.dev/subdir/path1/path2', Utils::url('/path1/path2', true));
+        self::assertSame('http://testing.dev/subdir/random/path1/path2', Utils::url('/random/path1/path2', true));
+        self::assertSame('http://testing.dev/subdir/foobar.jpg', Utils::url('/foobar.jpg', true));
+        self::assertSame('http://testing.dev/subdir/path1/foobar.jpg', Utils::url('/path1/foobar.jpg', true));
+        self::assertSame('http://testing.dev/subdir/path1/path2/foobar.jpg', Utils::url('/path1/path2/foobar.jpg', true));
+        self::assertSame('http://testing.dev/subdir/random/path1/path2/foobar.jpg', Utils::url('/random/path1/path2/foobar.jpg', true));
 
         // Paths including the grav base.
-        $this->assertSame('/subdir/', Utils::url('/subdir'));
-        $this->assertSame('/subdir/path1', Utils::url('/subdir/path1'));
-        $this->assertSame('/subdir/path1/path2', Utils::url('/subdir/path1/path2'));
-        $this->assertSame('/subdir/foobar.jpg', Utils::url('/subdir/foobar.jpg'));
-        $this->assertSame('/subdir/path1/foobar.jpg', Utils::url('/subdir/path1/foobar.jpg'));
+        self::assertSame('/subdir/', Utils::url('/subdir'));
+        self::assertSame('/subdir/path1', Utils::url('/subdir/path1'));
+        self::assertSame('/subdir/path1/path2', Utils::url('/subdir/path1/path2'));
+        self::assertSame('/subdir/foobar.jpg', Utils::url('/subdir/foobar.jpg'));
+        self::assertSame('/subdir/path1/foobar.jpg', Utils::url('/subdir/path1/foobar.jpg'));
 
         // Relative paths from Grav root with domain.
-        $this->assertSame('http://testing.dev/subdir/', Utils::url('/subdir', true));
-        $this->assertSame('http://testing.dev/subdir/path1', Utils::url('/subdir/path1', true));
-        $this->assertSame('http://testing.dev/subdir/path1/path2', Utils::url('/subdir/path1/path2', true));
-        $this->assertSame('http://testing.dev/subdir/foobar.jpg', Utils::url('/subdir/foobar.jpg', true));
-        $this->assertSame('http://testing.dev/subdir/path1/foobar.jpg', Utils::url('/subdir/path1/foobar.jpg', true));
+        self::assertSame('http://testing.dev/subdir/', Utils::url('/subdir', true));
+        self::assertSame('http://testing.dev/subdir/path1', Utils::url('/subdir/path1', true));
+        self::assertSame('http://testing.dev/subdir/path1/path2', Utils::url('/subdir/path1/path2', true));
+        self::assertSame('http://testing.dev/subdir/foobar.jpg', Utils::url('/subdir/foobar.jpg', true));
+        self::assertSame('http://testing.dev/subdir/path1/foobar.jpg', Utils::url('/subdir/path1/foobar.jpg', true));
 
         // Relative paths from Grav root.
-        $this->assertSame('/subdir/subdir', Utils::url('subdir'));
-        $this->assertSame('/subdir/subdir/path1', Utils::url('subdir/path1'));
-        $this->assertSame('/subdir/subdir/path1/path2', Utils::url('subdir/path1/path2'));
-        $this->assertSame('/subdir/path1', Utils::url('path1'));
-        $this->assertSame('/subdir/path1/path2', Utils::url('path1/path2'));
-        $this->assertSame('/subdir/foobar.jpg', Utils::url('foobar.jpg'));
-        $this->assertSame('http://testing.dev/subdir/foobar.jpg', Utils::url('foobar.jpg', true));
+        self::assertSame('/subdir/subdir', Utils::url('subdir'));
+        self::assertSame('/subdir/subdir/path1', Utils::url('subdir/path1'));
+        self::assertSame('/subdir/subdir/path1/path2', Utils::url('subdir/path1/path2'));
+        self::assertSame('/subdir/path1', Utils::url('path1'));
+        self::assertSame('/subdir/path1/path2', Utils::url('path1/path2'));
+        self::assertSame('/subdir/foobar.jpg', Utils::url('foobar.jpg'));
+        self::assertSame('http://testing.dev/subdir/foobar.jpg', Utils::url('foobar.jpg', true));
 
         // All Non-existing streams should be treated as external URI / protocol.
-        $this->assertSame('http://domain.com/path', Utils::url('http://domain.com/path'));
-        $this->assertSame('ftp://domain.com/path', Utils::url('ftp://domain.com/path'));
-        $this->assertSame('sftp://domain.com/path', Utils::url('sftp://domain.com/path'));
-        $this->assertSame('ssh://domain.com', Utils::url('ssh://domain.com'));
-        $this->assertSame('pop://domain.com', Utils::url('pop://domain.com'));
-        $this->assertSame('foo://bar/baz', Utils::url('foo://bar/baz'));
-        $this->assertSame('foo://bar/baz', Utils::url('foo://bar/baz', true));
-        // $this->assertSame('mailto:joe@domain.com', Utils::url('mailto:joe@domain.com', true)); // FIXME <-
+        self::assertSame('http://domain.com/path', Utils::url('http://domain.com/path'));
+        self::assertSame('ftp://domain.com/path', Utils::url('ftp://domain.com/path'));
+        self::assertSame('sftp://domain.com/path', Utils::url('sftp://domain.com/path'));
+        self::assertSame('ssh://domain.com', Utils::url('ssh://domain.com'));
+        self::assertSame('pop://domain.com', Utils::url('pop://domain.com'));
+        self::assertSame('foo://bar/baz', Utils::url('foo://bar/baz'));
+        self::assertSame('foo://bar/baz', Utils::url('foo://bar/baz', true));
+        // self::assertSame('mailto:joe@domain.com', Utils::url('mailto:joe@domain.com', true)); // FIXME <-
     }
 
-    public function testUrlWithStreams()
+    public function testUrlWithStreams(): void
     {
     }
 
-    public function testUrlwithExternals()
+    public function testUrlwithExternals(): void
     {
         $this->uri->initializeWithUrl('http://testing.dev/path1/path2')->init();
-        $this->assertSame('http://foo.com', Utils::url('http://foo.com'));
-        $this->assertSame('https://foo.com', Utils::url('https://foo.com'));
-        $this->assertSame('//foo.com', Utils::url('//foo.com'));
-        $this->assertSame('//foo.com?param=x', Utils::url('//foo.com?param=x'));
+        self::assertSame('http://foo.com', Utils::url('http://foo.com'));
+        self::assertSame('https://foo.com', Utils::url('https://foo.com'));
+        self::assertSame('//foo.com', Utils::url('//foo.com'));
+        self::assertSame('//foo.com?param=x', Utils::url('//foo.com?param=x'));
     }
 
-    public function testCheckFilename()
+    public function testCheckFilename(): void
     {
         // configure extension for consistent results
         /** @var \Grav\Common\Config\Config $config */
         $config = $this->grav['config'];
         $config->set('security.uploads_dangerous_extensions', ['php', 'html', 'htm', 'exe', 'js']);
 
-        $this->assertFalse(Utils::checkFilename('foo.php'));
-        $this->assertFalse(Utils::checkFilename('bar.js'));
+        self::assertFalse(Utils::checkFilename('foo.php'));
+        self::assertFalse(Utils::checkFilename('bar.js'));
 
-        $this->assertTrue(Utils::checkFilename('foo.json'));
-        $this->assertTrue(Utils::checkFilename('foo.xml'));
-        $this->assertTrue(Utils::checkFilename('foo.yaml'));
-        $this->assertTrue(Utils::checkFilename('foo.yml'));
+        self::assertTrue(Utils::checkFilename('foo.json'));
+        self::assertTrue(Utils::checkFilename('foo.xml'));
+        self::assertTrue(Utils::checkFilename('foo.yaml'));
+        self::assertTrue(Utils::checkFilename('foo.yml'));
     }
 }
diff --git a/tests/unit/Grav/Console/Gpm/InstallCommandTest.php b/tests/unit/Grav/Console/Gpm/InstallCommandTest.php
index da15594b1..94aef1ac8 100644
--- a/tests/unit/Grav/Console/Gpm/InstallCommandTest.php
+++ b/tests/unit/Grav/Console/Gpm/InstallCommandTest.php
@@ -2,6 +2,7 @@
 
 use Codeception\Util\Fixtures;
 use Grav\Common\Grav;
+use Grav\Console\Gpm\InstallCommand;
 
 /**
  * Class InstallCommandTest
@@ -15,13 +16,13 @@ class InstallCommandTest extends \Codeception\TestCase\Test
     protected $installCommand;
 
 
-    protected function _before()
+    protected function _before(): void
     {
         $this->grav = Fixtures::get('grav');
         $this->installCommand = new InstallCommand();
     }
 
-    protected function _after()
+    protected function _after(): void
     {
     }
 }
diff --git a/tests/unit/Grav/Framework/File/Formatter/CsvFormatterTest.php b/tests/unit/Grav/Framework/File/Formatter/CsvFormatterTest.php
index c2b321f25..7bff4e25f 100644
--- a/tests/unit/Grav/Framework/File/Formatter/CsvFormatterTest.php
+++ b/tests/unit/Grav/Framework/File/Formatter/CsvFormatterTest.php
@@ -2,9 +2,12 @@
 
 use Grav\Framework\File\Formatter\CsvFormatter;
 
+/**
+ * Class CsvFormatterTest
+ */
 class CsvFormatterTest extends \Codeception\TestCase\Test
 {
-    public function testEncodeWithAssocColumns()
+    public function testEncodeWithAssocColumns(): void
     {
         $data = [
             ['col1' => 1, 'col2' => 2, 'col3' => 3],
@@ -23,7 +26,7 @@ class CsvFormatterTest extends \Codeception\TestCase\Test
      * TBD - If indexes are all numeric, what's the purpose
      * of displaying header
      */
-    public function testEncodeWithIndexColumns()
+    public function testEncodeWithIndexColumns(): void
     {
         $data = [
             [0 => 1, 1 => 2, 2 => 3],
@@ -37,7 +40,7 @@ class CsvFormatterTest extends \Codeception\TestCase\Test
         self::assertEquals('0,1,2', $lines[0]);
     }
 
-    public function testEncodeEmptyData()
+    public function testEncodeEmptyData(): void
     {
         $encoded = (new CsvFormatter())->encode([]);
         self::assertEquals('', $encoded);
diff --git a/tests/unit/Grav/Framework/Filesystem/FilesystemTest.php b/tests/unit/Grav/Framework/Filesystem/FilesystemTest.php
index 86ef42a82..2aea40ca4 100644
--- a/tests/unit/Grav/Framework/Filesystem/FilesystemTest.php
+++ b/tests/unit/Grav/Framework/Filesystem/FilesystemTest.php
@@ -2,6 +2,9 @@
 
 use Grav\Framework\Filesystem\Filesystem;
 
+/**
+ * Class FilesystemTest
+ */
 class FilesystemTest extends \Codeception\TestCase\Test
 {
     protected $class;
@@ -277,17 +280,21 @@ class FilesystemTest extends \Codeception\TestCase\Test
         ],
     ];
 
-    protected function _before()
+    protected function _before(): void
     {
         $this->class = Filesystem::getInstance();
     }
 
-    protected function _after()
+    protected function _after(): void
     {
         unset($this->class);
     }
 
-    protected function runTestSet(array $tests, $method)
+    /**
+     * @param array $tests
+     * @param string $method
+     */
+    protected function runTestSet(array $tests, $method): void
     {
         $class = $this->class;
         foreach ($tests as $path => $candidates) {
@@ -299,32 +306,32 @@ class FilesystemTest extends \Codeception\TestCase\Test
 
             $result = $class->{$method}($path);
 
-            $this->assertSame($expected, $result, "Test {$method}('{$path}')");
+            self::assertSame($expected, $result, "Test {$method}('{$path}')");
 
             if (function_exists($method) && !strpos($path, '://')) {
                 $cmp_result = $method($path);
 
-                $this->assertSame($cmp_result, $result, "Compare to original {$method}('{$path}')");
+                self::assertSame($cmp_result, $result, "Compare to original {$method}('{$path}')");
             }
         }
     }
 
-    public function testParent()
+    public function testParent(): void
     {
         $this->runTestSet($this->tests, 'parent');
     }
 
-    public function testNormalize()
+    public function testNormalize(): void
     {
         $this->runTestSet($this->tests, 'normalize');
     }
 
-    public function testDirname()
+    public function testDirname(): void
     {
         $this->runTestSet($this->tests, 'dirname');
     }
 
-    public function testPathinfo()
+    public function testPathinfo(): void
     {
         $this->runTestSet($this->tests, 'pathinfo');
     }