Add connection exception.

Author: ergonlogic

src/CeleryAbstract.php

@@ -2,6 +2,8 @@
 
 namespace Celery;
 
+use PhpAmqpLib\Exception\AMQPProtocolConnectionException;
+
 /**
  * Client for a Celery server - abstract base class implementing actual logic
  * @package celery-php
@@ -57,10 +59,21 @@ public function BuildConnection($connection_details, $is_backend = false)
         }
     }
 
+    /**
+     * @throws CeleryConnectionException on connection failure.
+     */
     public static function InitializeAMQPConnection($details)
     {
         $amqp = AbstractAMQPConnector::GetConcrete($details['connector']);
-        return $amqp->GetConnectionObject($details);
+        try {
+            return $amqp->GetConnectionObject($details);
+        }
+        catch (AMQPProtocolConnectionException $e) {
+            throw new CeleryConnectionException("Failed to establish a AMQP connection. Check credentials.");
+        }
+        catch (Exception $e) {
+            throw new CeleryConnectionException("Failed to establish a AMQP connection. Unspecified failure.");
+        }
     }
 
     /**

src/CeleryConnectionException.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Celery;
+
+/**
+ * Emited by CeleryAbstract::PostTask() connection failures etc
+ * @package celery-php
+ */
+class CeleryConnectionException extends CeleryException
+{
+}