Ensure listener detachment works cross-version

Check if a returned callback is a CallbackHandler, and, if so, pull the actual
PHP callable from it before testing for the class. To ensure both BC and
forwards compatibility, ensure that the priority is stored when detaching, so
that re-attaching will continue to work.

In order to use `composer update --prefer-lowest`, I had to:

- update PHPUnit to `^4.5`, as that's the first version using prophecy, which we're
  using in tests now.
- add sebastian/version:^1.0.4, as that's the first version that fixes version
  autodiscovery, ensuring that the test runner knows we're on a version later
  than 2.5.

Author: weierophinney

composer.json

@@ -42,7 +42,8 @@
         "zendframework/zend-version": "^2.5",
         "zendframework/zend-view": "^2.6.3",
         "fabpot/php-cs-fixer": "1.7.*",
-        "phpunit/PHPUnit": "~4.0"
+        "phpunit/PHPUnit": "^4.5",
+        "sebastian/version": "^1.0.4"
     },
     "suggest": {
         "zendframework/zend-authentication": "Zend\\Authentication component for Identity plugin",

src/Controller/Plugin/Forward.php

@@ -15,6 +15,7 @@
 use Zend\Mvc\InjectApplicationEventInterface;
 use Zend\Mvc\MvcEvent;
 use Zend\Mvc\Router\RouteMatch;
+use Zend\Stdlib\CallbackHandler;
 
 class Forward extends AbstractPlugin
 {
@@ -178,9 +179,15 @@ protected function detachProblemListeners(SharedEvents $sharedEvents)
             foreach ($eventArray as $eventName => $classArray) {
                 $results[$id][$eventName] = [];
                 $events = $this->getSharedListenersById($id, $eventName, $sharedEvents);
-                foreach ($events as $currentEvent) {
+                foreach ($events as $priority => $currentEvent) {
                     $currentCallback = $currentEvent;
 
+                    // zend-eventmanager v2 compatibility:
+                    if ($currentCallback instanceof CallbackHandler) {
+                        $currentCallback = $currentCallback->getCallback();
+                        $priority        = $currentCallback->getMetadatum('priority');
+                    }
+
                     // If we have an array, grab the object
                     if (is_array($currentCallback)) {
                         $currentCallback = array_shift($currentCallback);
@@ -193,8 +200,11 @@ protected function detachProblemListeners(SharedEvents $sharedEvents)
 
                     foreach ($classArray as $class) {
                         if ($currentCallback instanceof $class) {
-                            $sharedEvents->detach($currentEvent, $id);
-                            $results[$id][$eventName][] = $currentEvent;
+                            // Pass $currentEvent; when using zend-eventmanager v2,
+                            // this is the CallbackHandler, while in v3 it's
+                            // the actual listener.
+                            $this->detachSharedListener($id, $currentEvent, $sharedEvents);
+                            $results[$id][$eventName][$priority] = $currentEvent;
                         }
                     }
                 }
@@ -215,8 +225,16 @@ protected function reattachProblemListeners(SharedEvents $sharedEvents, array $l
     {
         foreach ($listeners as $id => $eventArray) {
             foreach ($eventArray as $eventName => $callbacks) {
-                foreach ($callbacks as $current) {
-                    $sharedEvents->attach($id, $eventName, $current->getCallback(), $current->getMetadatum('priority'));
+                foreach ($callbacks as $priority => $current) {
+                    $callback = $current;
+
+                    // zend-eventmanager v2 compatibility:
+                    if ($current instanceof CallbackHandler) {
+                        $callback = $current->getCallback();
+                        $priority = $current->getMetadatum('priority');
+                    }
+
+                    $sharedEvents->attach($id, $eventName, $callback, $priority);
                 }
             }
         }
@@ -276,4 +294,26 @@ private function getSharedListenersById($id, $event, SharedEvents $sharedEvents)
         // v3
         return $sharedEvents->getListeners([$id], $event);
     }
+
+    /**
+     * Detach a shared listener by identifier.
+     *
+     * Varies detachment based on zend-eventmanager version.
+     *
+     * @param string|int $id
+     * @param callable|CallbackHandler $listener
+     * @param SharedEvents $sharedEvents
+     * @return void
+     */
+    private function detachSharedListener($id, $listener, SharedEvents $sharedEvents)
+    {
+        if (method_exists($sharedEvents, 'attachAggregate')) {
+            // v2
+            $sharedEvents->detach($id, $listener);
+            return;
+        }
+
+        // v3
+        $sharedEvents->detach($listener, $id);
+    }
 }