Do not allow a null middleware

Author: asgrim

src/MiddlewareListener.php

@@ -123,6 +123,7 @@ function (PsrServerRequestInterface $request, PsrResponseInterface $response) {
      * @param ResponseInterface $responsePrototype
      * @param array $middlewaresToBePiped
      * @return MiddlewarePipe
+     * @throws \InvalidArgumentException
      * @throws \Zend\Mvc\Exception\MiddlewareNotCallableException
      */
     private function createPipeFromSpec(
@@ -133,6 +134,10 @@ private function createPipeFromSpec(
         $pipe = new MiddlewarePipe();
         $pipe->setResponsePrototype($responsePrototype);
         foreach ($middlewaresToBePiped as $middlewareToBePiped) {
+            if (null === $middlewareToBePiped) {
+                throw new \InvalidArgumentException('Middleware name cannot be null');
+            }
+
             $middlewareName = is_string($middlewareToBePiped) ? $middlewareToBePiped : get_class($middlewareToBePiped);
 
             if (is_string($middlewareToBePiped) && $serviceLocator->has($middlewareToBePiped)) {

test/MiddlewareListenerTest.php

@@ -275,4 +275,39 @@ public function testMiddlewareWithNothingPipedReachesFinalHandlerException()
         $return   = $listener->onDispatch($event);
         $this->assertEquals('FAILED', $return);
     }
+
+    public function testNullMiddlewareThrowsInvalidArgument()
+    {
+        $response   = new Response();
+        $routeMatch = $this->prophesize(RouteMatch::class);
+        $routeMatch->getParams()->willReturn([]);
+        $routeMatch->getParam('middleware', false)->willReturn([null]);
+
+        $eventManager = new EventManager();
+
+        $serviceManager = $this->prophesize(ContainerInterface::class);
+        $application = $this->prophesize(Application::class);
+        $application->getEventManager()->willReturn($eventManager);
+        $application->getServiceManager()->will(function () use ($serviceManager) {
+            return $serviceManager->reveal();
+        });
+        $application->getResponse()->willReturn($response);
+
+        $event = new MvcEvent();
+        $event->setRequest(new Request());
+        $event->setResponse($response);
+        $event->setApplication($application->reveal());
+        $event->setRouteMatch($routeMatch->reveal());
+
+        $event->getApplication()->getEventManager()->attach(MvcEvent::EVENT_DISPATCH_ERROR, function ($e) {
+            $this->assertEquals(Application::ERROR_EXCEPTION, $e->getError());
+            $this->assertInstanceOf(ReachedFinalHandlerException::class, $e->getParam('exception'));
+            return 'FAILED';
+        });
+
+        $listener = new MiddlewareListener();
+
+        $this->setExpectedException(\InvalidArgumentException::class);
+        $listener->onDispatch($event);
+    }
 }