symfony · javiereguiluz · Jul 5, 2017 · Jul 10, 2017 · xabbuh · Jul 5, 2017
diff --git a/configuration/multiple_kernels.rst b/configuration/multiple_kernels.rst
@@ -178,6 +178,43 @@ In order to solve this issue, add the following configuration to your kernel:
            # allows to use app/Resources/views/ templates in the ApiKernel
            "%kernel.root_dir%/../app/Resources/views": ~

+Running Tests Using a Different Kernel
+--------------------------------------
+
+In Symfony applications, functional tests extend by default from the
+:class:`Symfony\\Bundle\\FrameworkBundle\\Test\\WebTestCase` class. Inside that
+class, a method called ``getKernelClass()`` tries to find the class of the kernel
+to use to run the application during tests. The logic of this method does not
+support multiple kernel applications, so your tests won't use the right kernel.
+
+The solution is to create a custom base class for functional tests extending
+from ``WebTestCase`` class and overriding the ``getKernelClass()`` method to
+return the fully qualified class name of the kernel to use::
+
+    use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+
+    // tests needing the ApiKernel to work, now must extend this
+    // ApiTestCase class instead of the default WebTestCase class
+    class ApiTestCase extends WebTestCase
+    {
+        protected static function getKernelClass()
+        {
+            return 'ApiKernel';
+        }
+
+        // this is needed because the KernelTestCase class keeps a reference to
+        // the previously created kernel in its static $kernel property. Thus,
+        // if your functional tests do not run in isolated processes, a later run
+        // test for a different kernel will reuse the previously created instance,
+        // which points to a different kernel
+        protected function tearDown()
+        {
+            parent::tearDown();
+
+            static::$class = null;
+        }
+    }
+
 Adding more Kernels to the Application
 --------------------------------------
-Original file line number
+Diff line change
@@ -178,6 +178,43 @@ In order to solve this issue, add the following configuration to your kernel:
                 # allows to use app/Resources/views/ templates in the ApiKernel
                 "%kernel.root_dir%/../app/Resources/views": ~
+    Running Tests Using a Different Kernel
+    --------------------------------------
+    In Symfony applications, functional tests extend by default from the
+    :class:`Symfony\\Bundle\\FrameworkBundle\\Test\\WebTestCase` class. Inside that
+    class, a method called ``getKernelClass()`` tries to find the class of the kernel
+    to use to run the application during tests. The logic of this method does not
+    support multiple kernel applications, so your tests won't use the right kernel.
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            xabbuh
  

      

      

      


        Jul 5, 2017


      
    

  


        
      
  
  
  
    

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      We need to be careful here. The approach described here does not solve the issue when you have more than one kernel. The problem then still is that the KernelTestCase class keeps a reference to the previously created kernel in its static $kernel property. Thus, if your functional tests do not run in isolated processes a later run test for a different kernel will reuse the previously created instance which points to a different kernel.
    
  
  


    

        
      
  
  
    
  
  
  
    
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            javiereguiluz
  

      

      

      


        Jul 6, 2017


      
    

  


        
      
  
  
  
    

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      Thanks for the explanation! You are right and this is critical. What would be the best (and simplest) solution to this problem?
    
  
  


    

        
      
  
  
    
  
  
  
    
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        Jul 9, 2017


      
    

  


        
      
  
  
  
    

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      It should be sufficient to always reset the static $class property inside the tearDown() method:
protected function tearDown()
{
    parent::tearDown();

    static::$class = null;
}
The parent::tearDown() call is important to make sure that the kernel is shut down after the test was run.
    
  
  


    

        
      
  
  
    
  
  
  
    
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        Jul 10, 2017


      
    

  


        
      
  
  
  
    

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      Thanks!! I've fixed the code and reused your original explanation because it's great.
    
  
  


    

        
      
  
  
    
  
  
  
    
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+    The solution is to create a custom base class for functional tests extending
+    from ``WebTestCase`` class and overriding the ``getKernelClass()`` method to
+    return the fully qualified class name of the kernel to use::
+        use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+        // tests needing the ApiKernel to work, now must extend this
+        // ApiTestCase class instead of the default WebTestCase class
+        class ApiTestCase extends WebTestCase
+        {
+            protected static function getKernelClass()
+            {
+                return 'ApiKernel';
+            }
+            // this is needed because the KernelTestCase class keeps a reference to
+            // the previously created kernel in its static $kernel property. Thus,
+            // if your functional tests do not run in isolated processes, a later run
+            // test for a different kernel will reuse the previously created instance,
+            // which points to a different kernel
+            protected function tearDown()
+            {
+                parent::tearDown();
+                static::$class = null;
+            }
+        }
     Adding more Kernels to the Application
     --------------------------------------
-          Expand Down