[HttpKernel] DebugHandlersListener should always replace the existing exception handler

.travis.yml

@@ -181,7 +181,7 @@ install:
           elif [[ $deps = low ]]; then
               echo "$COMPONENTS" | parallel --gnu -j10% "tfold {} 'cd {} && $COMPOSER_UP --prefer-lowest --prefer-stable && $PHPUNIT_X'"
           elif [[ $PHP = hhvm* ]]; then
-              $PHPUNIT --exclude-group benchmark,intl-data
+              $PHPUNIT --exclude-group no-hhvm,benchmark,intl-data
           else
               echo "$COMPONENTS" | parallel --gnu "tfold {} $PHPUNIT_X {}"
               tfold tty-group $PHPUNIT --group tty

src/Symfony/Component/Debug/Tests/ErrorHandlerTest.php

@@ -293,6 +293,9 @@ class ErrorHandlerTest extends TestCase
         @$handler->handleError(E_USER_DEPRECATED, 'Foo deprecation', __FILE__, __LINE__, array());
     }
 
+    /**
+     * @group no-hhvm
+     */
     public function testHandleException()
     {
         try {
@@ -375,6 +378,9 @@ class ErrorHandlerTest extends TestCase
         }
     }
 
+    /**
+     * @group no-hhvm
+     */
     public function testHandleFatalError()
     {
         try {
@@ -434,6 +440,9 @@ class ErrorHandlerTest extends TestCase
         $this->assertStringStartsWith("Attempted to load class \"Foo\" from the global namespace.\nDid you forget a \"use\" statement", $args[0]->getMessage());
     }
 
+    /**
+     * @group no-hhvm
+     */
     public function testHandleFatalErrorOnHHVM()
     {
         try {

src/Symfony/Component/Debug/Tests/phpt/decorate_exception_hander.phpt

@@ -0,0 +1,47 @@
+--TEST--
+Test catching fatal errors when handlers are nested
+--FILE--
+<?php
+
+namespace Symfony\Component\Debug;
+
+$vendor = __DIR__;
+while (!file_exists($vendor.'/vendor')) {
+    $vendor = dirname($vendor);
+}
+require $vendor.'/vendor/autoload.php';
+
+set_error_handler('var_dump');
+set_exception_handler('var_dump');
+
+ErrorHandler::register(null, false);
+
+if (true) {
+    class foo extends missing
+    {
+    }
+}
+
+?>
+--EXPECTF--
+Fatal error: Class 'Symfony\Component\Debug\missing' not found in %s on line %d
+object(Symfony\Component\Debug\Exception\ClassNotFoundException)#%d (8) {
+  ["message":protected]=>
+  string(131) "Attempted to load class "missing" from namespace "Symfony\Component\Debug".
+Did you forget a "use" statement for another namespace?"
+  ["string":"Exception":private]=>
+  string(0) ""
+  ["code":protected]=>
+  int(0)
+  ["file":protected]=>
+  string(%d) "%s"
+  ["line":protected]=>
+  int(%d)
+  ["trace":"Exception":private]=>
+  array(0) {
+  }
+  ["previous":"Exception":private]=>
+  NULL
+  ["severity":protected]=>
+  int(1)
+}

src/Symfony/Component/Debug/Tests/phpt/fatal_with_nested_handlers.phpt

@@ -35,7 +35,7 @@ array(1) {
   [0]=>
   string(37) "Error and exception handlers do match"
 }
-object(Symfony\Component\Debug\Exception\FatalErrorException)#4 (8) {
+object(Symfony\Component\Debug\Exception\FatalErrorException)#%d (8) {
   ["message":protected]=>
   string(199) "Error: Class Symfony\Component\Debug\Broken contains 2 abstract methods and must therefore be declared abstract or implement the remaining methods (Serializable::serialize, Serializable::unserialize)"
 %a

src/Symfony/Component/HttpKernel/EventListener/DebugHandlersListener.php

@@ -117,9 +117,13 @@ class DebugHandlersListener implements EventSubscriberInterface
         }
         if ($this->exceptionHandler) {
             if ($handler instanceof ErrorHandler) {
-                $h = $handler->setExceptionHandler('var_dump') ?: $this->exceptionHandler;
-                $handler->setExceptionHandler($h);
-                $handler = is_array($h) ? $h[0] : null;
+                $h = $handler->setExceptionHandler('var_dump');
+                if (is_array($h) && $h[0] instanceof ExceptionHandler) {
+                    $handler->setExceptionHandler($h);
+                    $handler = $h[0];
+                } else {
+                    $handler->setExceptionHandler($this->exceptionHandler);
+                }
             }
             if ($handler instanceof ExceptionHandler) {
                 $handler->setHandler($this->exceptionHandler);

src/Symfony/Component/HttpKernel/Tests/EventListener/DebugHandlersListenerTest.php

@@ -29,8 +29,6 @@ use Symfony\Component\HttpKernel\HttpKernelInterface;
 use Symfony\Component\HttpKernel\KernelEvents;
 
 /**
- * DebugHandlersListenerTest.
- *
  * @author Nicolas Grekas <p@tchwork.com>
  */
 class DebugHandlersListenerTest extends TestCase
@@ -132,4 +130,26 @@ class DebugHandlersListenerTest extends TestCase
 
         $xHandler(new \Exception());
     }
+
+    public function testReplaceExistingExceptionHandler()
+    {
+        $userHandler = function () {};
+        $listener = new DebugHandlersListener($userHandler);
+        $eHandler = new ErrorHandler();
+        $eHandler->setExceptionHandler('var_dump');
+
+        $exception = null;
+        set_exception_handler(array($eHandler, 'handleException'));
+        try {
+            $listener->configure();
+        } catch (\Exception $exception) {
+        }
+        restore_exception_handler();
+
+        if (null !== $exception) {
+            throw $exception;
+        }
+
+        $this->assertSame($userHandler, $eHandler->setExceptionHandler('var_dump'));
+    }
 }