[ticket/11202] Add a heuristic function to check for response success.

This tries to account for php sending fatal errors with 200 status code.

PHPBB3-11202

tests/test_framework/phpbb_functional_test_case.php

@@ -229,4 +229,19 @@ class phpbb_functional_test_case extends phpbb_test_case
 
 		return call_user_func_array('sprintf', $args);
 	}
+
+	/**
+	* Heuristic function to check that the response is success.
+	*
+	* When php decides to die with a fatal error, it still sends 200 OK
+	* status code. This assertion tries to catch that.
+	*
+	* @param string $message Optional failure message
+	*/
+	public function assert_response_success($message = null)
+	{
+		$this->assertEquals(200, $this->client->getResponse()->getStatus());
+		$content = $this->client->getResponse()->getContent();
+		$this->assertNotContains('Fatal error:', $content);
+	}
 }