[HttpKernel] enabling cache-reloading when cache file is rebuilt

This allows the cache file to be deleted and thus rebuilt between Container builds in WebTestCase scenario, to enable testing of multiple configurations of the same application through WebTestCase.
symfony · stampycode · Sep 23, 2016 · Sep 28, 2016 · Sep 28, 2016 · Sep 28, 2016
commit 977b27f2cd2c5a27d98abfb7aa68a3221da2266a
diff --git a/src/Symfony/Component/HttpKernel/Kernel.php b/src/Symfony/Component/HttpKernel/Kernel.php
@@ -482,12 +482,17 @@ protected function initializeContainer()
         if (!$cache->isFresh()) {
             $container = $this->buildContainer();
             $container->compile();
+            $class = $this->getNextClassVersion($class);
             $this->dumpContainer($cache, $container, $class, $this->getContainerBaseClass());
 
             $fresh = false;
+        } else {
+            $class = $this->getLatestClassVersion($class);
         }
 
-        require_once $cache->getPath();
+        if(!class_exists($class)) {
+            require $cache->getPath();
+        }
 
         $this->container = new $class();
         $this->container->set('kernel', $this);
@@ -497,6 +502,34 @@ protected function initializeContainer()
         }
     }
 
+    /**
+     * Returns the first version of the given class name that doesn't yet exist.
+     *
+     * eg. 'MyClass' is the first version, 'MyClass1' the second, 'MyClass2' the second, etc.
+     *
+     * @param string $class
+     * @return string
+     */
+    protected function getNextClassVersion($class)
+    {
+        for ($classVer = 0; class_exists($class . ($classVer ?: '')); $classVer++);
+
+        return $class . ($classVer ?: '');
+    }
+
+    /**
+     * Returns the last version of the given class name that does exist
+     *
+     * @param string $class
+     * @return string
+     */
+    protected function getLatestClassVersion($class)
+    {
+        for ($classVer = 0; class_exists($class . ($classVer ?: '')); $classVer++);
+
+        return $class . ($classVer > 1 ? $classVer - 1 : '');
+    }
+
     /**
      * Returns the kernel parameters.
      *