diff --git a/test/phpunit/NumberingModulesTest.php b/test/phpunit/NumberingModulesTest.php
index 7bd96c2d4bf..008ffe6ce94 100644
--- a/test/phpunit/NumberingModulesTest.php
+++ b/test/phpunit/NumberingModulesTest.php
@@ -131,6 +131,7 @@ class NumberingModulesTest extends PHPUnit_Framework_TestCase
 
 		// First we try with a simple mask, with no reset
 		// and we test counter is still increase second year.
+		$conf->global->FACTURE_ADDON='mercure';
 		$conf->global->FACTURE_MERCURE_MASK_CREDIT='{yyyy}-{0000}';
 		$conf->global->FACTURE_MERCURE_MASK_INVOICE='{yyyy}-{0000}';
 
@@ -143,17 +144,29 @@ class NumberingModulesTest extends PHPUnit_Framework_TestCase
 		$result3=$localobject->validate($user, $result);		// create invoice by forcing ref
 		print __METHOD__." result=".$result."\n";
 		$this->assertEquals('1915-0001', $result);				// counter must start to 1
-
-		$localobject=new Facture($this->savdb);
-		$localobject->initAsSpecimen();
-		$localobject->date=dol_mktime(12, 0, 0, 1, 1, 1916);	// we use following year for second invoice (there is no reset into mask)
+		$result=$localobject->is_erasable();
+		print __METHOD__." is_erasable=".$result."\n";
+		$this->assertEquals(1, $result);						// Can be deleted
+		
+		$localobject2=new Facture($this->savdb);
+		$localobject2->initAsSpecimen();
+		$localobject2->date=dol_mktime(12, 0, 0, 1, 1, 1916);	// we use following year for second invoice (there is no reset into mask)
 		$numbering=new mod_facture_mercure();
-		$result=$numbering->getNextValue($mysoc, $localobject, 'last');
+		$result=$numbering->getNextValue($mysoc, $localobject2, 'last');
+		print __METHOD__." result=".$result."\n";
 		$this->assertEquals('1915-0001', $result);
-		$result=$numbering->getNextValue($mysoc, $localobject);
+		$result=$numbering->getNextValue($mysoc, $localobject2);
+		$result2=$localobject2->create($user,1);
+		$result3=$localobject2->validate($user, $result);		// create invoice by forcing ref
 		print __METHOD__." result=".$result."\n";
 		$this->assertEquals('1916-0002', $result);				// counter must not be reseted so be 2
-
+		$result=$localobject2->is_erasable();
+		print __METHOD__." is_erasable=".$result."\n";
+		$this->assertEquals(1, $result);						// Can be deleted
+		$result=$localobject->is_erasable();
+		print __METHOD__." is_erasable=".$result."\n";
+		$this->assertEquals(0, $result);						// Case 1 can not be deleted (case 2 is more recent)
+		
 		// Now we try with a reset
 		$conf->global->FACTURE_MERCURE_MASK_CREDIT='{yyyy}-{0000@1}';
 		$conf->global->FACTURE_MERCURE_MASK_INVOICE='{yyyy}-{0000@1}';
@@ -178,15 +191,26 @@ class NumberingModulesTest extends PHPUnit_Framework_TestCase
 		$result3=$localobject->validate($user, $result);
 		print __METHOD__." result=".$result."\n";
 		$this->assertEquals('192001-0001', $result);			// counter must start to 1
-
-		$localobject=new Facture($this->savdb);
-		$localobject->initAsSpecimen();
-		$localobject->date=dol_mktime(12, 0, 0, 1, 1, 1921);	// we use following year for second invoice (and there is a reset required)
+		$result=$localobject->is_erasable();
+		print __METHOD__." is_erasable=".$result."\n";
+		$this->assertEquals(1, $result);						// Can be deleted
+		
+		$localobject2=new Facture($this->savdb);
+		$localobject2->initAsSpecimen();
+		$localobject2->date=dol_mktime(12, 0, 0, 1, 1, 1921);	// we use following year for second invoice (and there is a reset required)
 		$numbering=new mod_facture_mercure();
-		$result=$numbering->getNextValue($mysoc, $localobject);
-    	print __METHOD__." result=".$result."\n";
+		$result=$numbering->getNextValue($mysoc, $localobject2);
+		$result2=$localobject2->create($user,1);
+		$result3=$localobject2->validate($user, $result);
+		print __METHOD__." result=".$result."\n";
     	$this->assertEquals('192101-0001', $result);			// counter must be reseted to 1
-
+    	$result=$localobject2->is_erasable();
+    	print __METHOD__." is_erasable=".$result."\n";
+    	$this->assertEquals(1, $result);						// Can be deleted
+    	$result=$localobject->is_erasable();
+    	print __METHOD__." is_erasable=".$result."\n";
+    	$this->assertEquals(1, $result);						// Case 1 can be deleted (because there was a reset for case 2)
+    	 
 
 		// Now we try with a different fiscal month (forced by mask)
     	$conf->global->FACTURE_MERCURE_MASK_CREDIT='{yyyy}{mm}-{0000@6}';
@@ -233,7 +257,7 @@ class NumberingModulesTest extends PHPUnit_Framework_TestCase
 
     	$localobject=new Facture($this->savdb);
     	$localobject->initAsSpecimen();
-    	$localobject->date=dol_mktime(12, 0, 0, 12, 1, 1931);	// we use different discal year but same year
+    	$localobject->date=dol_mktime(12, 0, 0, 12, 1, 1931);	// we use different fiscal year but same year
     	$numbering=new mod_facture_mercure();
     	$result=$numbering->getNextValue($mysoc, $localobject);
     	print __METHOD__." result=".$result."\n";