diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 29307d8..54bbfa4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,6 +9,7 @@ jobs:
       matrix:
         php-version: ['7.4', '8.0', '8.1' ]
         symfony-version: ['^4.4', '^5.0']
+        amqp-version: ['1.11.0', '2.1.2']
       fail-fast: false
     steps:
       - uses: actions/checkout@master
@@ -16,7 +17,7 @@ jobs:
         with:
           php-version: ${{ matrix.php-version }}
           coverage: xdebug2
-          extensions: amqp
+          extensions: amqp-${{ matrix.amqp-version }}
       - name: Install symfony version from matrix
         env:
           SYMFONY_VERSION: ${{ matrix.symfony-version }}
diff --git a/src/AmqpBundle/Amqp/Consumer.php b/src/AmqpBundle/Amqp/Consumer.php
index 766e7ad..08eaad0 100644
--- a/src/AmqpBundle/Amqp/Consumer.php
+++ b/src/AmqpBundle/Amqp/Consumer.php
@@ -34,7 +34,6 @@ public function __construct(\AMQPQueue $queue, array $queueOptions)
     public function getMessage(int $flags = AMQP_AUTOACK): ?\AMQPEnvelope
     {
         $envelope = $this->call($this->queue, 'get', [$flags]);
-        $envelope = $envelope === false ? null : $envelope;
 
         if ($this->eventDispatcher) {
             $preRetrieveEvent = new PreRetrieveEvent($envelope);
@@ -49,13 +48,13 @@ public function getMessage(int $flags = AMQP_AUTOACK): ?\AMQPEnvelope
     /**
      * Acknowledge the receipt of a message.
      *
-     * @param string $deliveryTag delivery tag of last message to ack
+     * @param int $deliveryTag delivery tag of last message to ack
      * @param int    $flags       AMQP_MULTIPLE or AMQP_NOPARAM
      *
      * @throws \AMQPChannelException    if the channel is not open
      * @throws \AMQPConnectionException if the connection to the broker was lost
      */
-    public function ackMessage(string $deliveryTag, int $flags = AMQP_NOPARAM): bool
+    public function ackMessage(int $deliveryTag, int $flags = AMQP_NOPARAM): void
     {
         if ($this->eventDispatcher) {
             $ackEvent = new AckEvent($deliveryTag, $flags);
@@ -63,19 +62,19 @@ public function ackMessage(string $deliveryTag, int $flags = AMQP_NOPARAM): bool
             $this->eventDispatcher->dispatch($ackEvent,AckEvent::NAME);
         }
 
-        return $this->call($this->queue, 'ack', [$deliveryTag, $flags]);
+        $this->call($this->queue, 'ack', [$deliveryTag, $flags]);
     }
 
     /**
      * Mark a message as explicitly not acknowledged.
      *
-     * @param string $deliveryTag delivery tag of last message to nack
+     * @param int $deliveryTag delivery tag of last message to nack
      * @param int    $flags       AMQP_NOPARAM or AMQP_REQUEUE to requeue the message(s)
      *
      * @throws \AMQPConnectionException if the connection to the broker was lost
      * @throws \AMQPChannelException    if the channel is not open
      */
-    public function nackMessage(string $deliveryTag, int $flags = AMQP_NOPARAM): bool
+    public function nackMessage(int $deliveryTag, int $flags = AMQP_NOPARAM): void
     {
         if ($this->eventDispatcher) {
             $nackEvent = new NackEvent($deliveryTag, $flags);
@@ -83,7 +82,7 @@ public function nackMessage(string $deliveryTag, int $flags = AMQP_NOPARAM): boo
             $this->eventDispatcher->dispatch($nackEvent, NackEvent::NAME);
         }
 
-        return $this->call($this->queue, 'nack', [$deliveryTag, $flags]);
+        $this->call($this->queue, 'nack', [$deliveryTag, $flags]);
     }
 
     /**
@@ -92,7 +91,7 @@ public function nackMessage(string $deliveryTag, int $flags = AMQP_NOPARAM): boo
      * @throws \AMQPChannelException    if the channel is not open
      * @throws \AMQPConnectionException if the connection to the broker was lost
      */
-    public function purge(): bool
+    public function purge(): int
     {
         if ($this->eventDispatcher) {
             $purgeEvent = new PurgeEvent($this->queue);
diff --git a/src/AmqpBundle/Amqp/Producer.php b/src/AmqpBundle/Amqp/Producer.php
index 3af083f..0760691 100644
--- a/src/AmqpBundle/Amqp/Producer.php
+++ b/src/AmqpBundle/Amqp/Producer.php
@@ -33,7 +33,7 @@ public function __construct(\AMQPExchange $exchange, array $exchangeOptions)
      *                            timestamp, expiration, type or reply_to
      * @param array  $routingKeys If set, overrides the Producer 'routing_keys' for this message
      *
-     * @return bool tRUE on success or FALSE on failure
+     * @return bool TRUE on success or throws on failure
      *
      * @throws \AMQPExchangeException   on failure
      * @throws \AMQPChannelException    if the channel is not open
@@ -63,16 +63,17 @@ public function publishMessage(string $message, int $flags = AMQP_NOPARAM, array
         }
 
         if (!$routingKeys) {
-            return $this->call($this->exchange, 'publish', [$message, null, $flags, $attributes]);
+            $this->call($this->exchange, 'publish', [$message, null, $flags, $attributes]);
+
+            return true;
         }
 
         // Publish the message for each routing keys
-        $success = true;
         foreach ($routingKeys as $routingKey) {
-            $success &= $this->call($this->exchange, 'publish', [$message, $routingKey, $flags, $attributes]);
+            $this->call($this->exchange, 'publish', [$message, $routingKey, $flags, $attributes]);
         }
 
-        return (bool) $success;
+        return true;
     }
 
     public function getExchange(): \AMQPExchange
diff --git a/src/AmqpBundle/Event/AckEvent.php b/src/AmqpBundle/Event/AckEvent.php
index 518f6b5..849b36c 100644
--- a/src/AmqpBundle/Event/AckEvent.php
+++ b/src/AmqpBundle/Event/AckEvent.php
@@ -11,17 +11,17 @@ class AckEvent extends Event
 {
     const NAME = 'amqp.ack';
 
-    private string $deliveryTag;
+    private int $deliveryTag;
 
     private int $flags;
 
-    public function __construct(string $deliveryTag, int $flags)
+    public function __construct(int $deliveryTag, int $flags)
     {
         $this->deliveryTag = $deliveryTag;
         $this->flags = $flags;
     }
 
-    public function getDeliveryTag(): string
+    public function getDeliveryTag(): int
     {
         return $this->deliveryTag;
     }
diff --git a/src/AmqpBundle/Event/NackEvent.php b/src/AmqpBundle/Event/NackEvent.php
index 46a02d7..eb977d8 100644
--- a/src/AmqpBundle/Event/NackEvent.php
+++ b/src/AmqpBundle/Event/NackEvent.php
@@ -11,16 +11,16 @@ class NackEvent extends Event
 {
     const NAME = 'amqp.nack';
 
-    private string $deliveryTag;
+    private int $deliveryTag;
     private int $flags;
 
-    public function __construct(string $deliveryTag, int $flags)
+    public function __construct(int $deliveryTag, int $flags)
     {
         $this->deliveryTag = $deliveryTag;
         $this->flags = $flags;
     }
 
-    public function getDeliveryTag(): string
+    public function getDeliveryTag(): int
     {
         return $this->deliveryTag;
     }
diff --git a/src/AmqpBundle/Sandbox/NullConnection.php b/src/AmqpBundle/Sandbox/NullConnection.php
index 77c69e8..1998f6d 100644
--- a/src/AmqpBundle/Sandbox/NullConnection.php
+++ b/src/AmqpBundle/Sandbox/NullConnection.php
@@ -10,48 +10,42 @@ class NullConnection extends \AMQPConnection
     /**
      * {@inheritdoc}
      */
-    public function connect()
+    public function connect(): void
     {
-        return true;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function pconnect()
+    public function pconnect(): void
     {
-        return true;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function pdisconnect()
+    public function pdisconnect(): void
     {
-        return true;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function disconnect()
+    public function disconnect(): void
     {
-        return true;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function reconnect()
+    public function reconnect(): void
     {
-        return true;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function preconnect()
+    public function preconnect(): void
     {
-        return true;
     }
 }
diff --git a/src/AmqpBundle/Sandbox/NullEnvelope.php b/src/AmqpBundle/Sandbox/NullEnvelope.php
index 588c63c..381fb6b 100644
--- a/src/AmqpBundle/Sandbox/NullEnvelope.php
+++ b/src/AmqpBundle/Sandbox/NullEnvelope.php
@@ -7,87 +7,33 @@
  */
 class NullEnvelope extends \AMQPEnvelope
 {
-    /**
-     * @var string
-     */
-    private $body;
-    /**
-     * @var string
-     */
-    private $routingKey;
-    /**
-     * @var string
-     */
-    private $deliveryTag;
-    /**
-     * @var string
-     */
-    private $deliveryMode;
-    /**
-     * @var bool
-     */
-    private $redelivery;
-    /**
-     * @var string
-     */
-    private $contentType;
-    /**
-     * @var string
-     */
-    private $contentEncoding;
-    /**
-     * @var string
-     */
-    private $type;
-    /**
-     * @var string
-     */
-    private $timestamp;
-    /**
-     * @var int
-     */
-    private $priority;
-    /**
-     * @var string
-     */
-    private $expiration;
-    /**
-     * @var string
-     */
-    private $userId;
-    /**
-     * @var string
-     */
-    private $appId;
-    /**
-     * @var string
-     */
-    private $messageId;
-    /**
-     * @var string
-     */
-    private $replyTo;
-    /**
-     * @var string
-     */
-    private $correlationId;
-    /**
-     * @var array
-     */
-    private $headers;
+    private string $body;
+    private string $routingKey;
+    private int $deliveryTag;
+    private int $deliveryMode;
+    private bool $redelivery;
+    private string $contentType;
+    private string $contentEncoding;
+    private string $type;
+    private string $timestamp;
+    private int $priority;
+    private string $expiration;
+    private string $userId;
+    private string $appId;
+    private string $messageId;
+    private string $replyTo;
+    private string $correlationId;
+    private array $headers;
 
     /**
      * {@inheritdoc}
      */
-    public function getBody()
+    public function getBody(): string
     {
         return $this->body;
     }
 
-    /**
-     * @param string $body
-     */
-    public function setBody($body)
+    public function setBody(string $body): void
     {
         $this->body = $body;
     }
@@ -95,15 +41,12 @@ public function setBody($body)
     /**
      * {@inheritdoc}
      */
-    public function getRoutingKey()
+    public function getRoutingKey(): string
     {
         return $this->routingKey;
     }
 
-    /**
-     * @param string $routingKey
-     */
-    public function setRoutingKey($routingKey)
+    public function setRoutingKey(string $routingKey): void
     {
         $this->routingKey = $routingKey;
     }
@@ -111,15 +54,12 @@ public function setRoutingKey($routingKey)
     /**
      * {@inheritdoc}
      */
-    public function getDeliveryTag()
+    public function getDeliveryTag(): int
     {
         return $this->deliveryTag;
     }
 
-    /**
-     * @param string $deliveryTag
-     */
-    public function setDeliveryTag($deliveryTag)
+    public function setDeliveryTag(int $deliveryTag): void
     {
         $this->deliveryTag = $deliveryTag;
     }
@@ -127,15 +67,12 @@ public function setDeliveryTag($deliveryTag)
     /**
      * {@inheritdoc}
      */
-    public function getDeliveryMode()
+    public function getDeliveryMode(): int
     {
         return $this->deliveryMode;
     }
 
-    /**
-     * @param string $deliveryMode
-     */
-    public function setDeliveryMode($deliveryMode)
+    public function setDeliveryMode(int $deliveryMode): void
     {
         $this->deliveryMode = $deliveryMode;
     }
@@ -143,15 +80,12 @@ public function setDeliveryMode($deliveryMode)
     /**
      * {@inheritdoc}
      */
-    public function isRedelivery()
+    public function isRedelivery(): bool
     {
         return $this->redelivery;
     }
 
-    /**
-     * @param bool $redelivery
-     */
-    public function setRedelivery($redelivery)
+    public function setRedelivery(bool $redelivery): void
     {
         $this->redelivery = $redelivery;
     }
@@ -159,15 +93,12 @@ public function setRedelivery($redelivery)
     /**
      * {@inheritdoc}
      */
-    public function getContentType()
+    public function getContentType(): string
     {
         return $this->contentType;
     }
 
-    /**
-     * @param string $contentType
-     */
-    public function setContentType($contentType)
+    public function setContentType(string $contentType): void
     {
         $this->contentType = $contentType;
     }
@@ -175,15 +106,12 @@ public function setContentType($contentType)
     /**
      * {@inheritdoc}
      */
-    public function getContentEncoding()
+    public function getContentEncoding(): string
     {
         return $this->contentEncoding;
     }
 
-    /**
-     * @param string $contentEncoding
-     */
-    public function setContentEncoding($contentEncoding)
+    public function setContentEncoding(string $contentEncoding): void
     {
         $this->contentEncoding = $contentEncoding;
     }
@@ -191,15 +119,12 @@ public function setContentEncoding($contentEncoding)
     /**
      * {@inheritdoc}
      */
-    public function getType()
+    public function getType(): string
     {
         return $this->type;
     }
 
-    /**
-     * @param string $type
-     */
-    public function setType($type)
+    public function setType(string $type): void
     {
         $this->type = $type;
     }
@@ -207,15 +132,12 @@ public function setType($type)
     /**
      * {@inheritdoc}
      */
-    public function getTimestamp()
+    public function getTimestamp(): ?int
     {
         return $this->timestamp;
     }
 
-    /**
-     * @param string $timestamp
-     */
-    public function setTimestamp($timestamp)
+    public function setTimestamp(string $timestamp): void
     {
         $this->timestamp = $timestamp;
     }
@@ -223,15 +145,12 @@ public function setTimestamp($timestamp)
     /**
      * {@inheritdoc}
      */
-    public function getPriority()
+    public function getPriority(): int
     {
         return $this->priority;
     }
 
-    /**
-     * @param int $priority
-     */
-    public function setPriority($priority)
+    public function setPriority(int $priority): void
     {
         $this->priority = $priority;
     }
@@ -239,15 +158,12 @@ public function setPriority($priority)
     /**
      * {@inheritdoc}
      */
-    public function getExpiration()
+    public function getExpiration(): string
     {
         return $this->expiration;
     }
 
-    /**
-     * @param string $expiration
-     */
-    public function setExpiration($expiration)
+    public function setExpiration(string $expiration): void
     {
         $this->expiration = $expiration;
     }
@@ -255,15 +171,12 @@ public function setExpiration($expiration)
     /**
      * {@inheritdoc}
      */
-    public function getUserId()
+    public function getUserId(): string
     {
         return $this->userId;
     }
 
-    /**
-     * @param string $userId
-     */
-    public function setUserId($userId)
+    public function setUserId(string $userId): void
     {
         $this->userId = $userId;
     }
@@ -271,15 +184,12 @@ public function setUserId($userId)
     /**
      * {@inheritdoc}
      */
-    public function getAppId()
+    public function getAppId(): string
     {
         return $this->appId;
     }
 
-    /**
-     * @param string $appId
-     */
-    public function setAppId($appId)
+    public function setAppId(string $appId): void
     {
         $this->appId = $appId;
     }
@@ -287,15 +197,12 @@ public function setAppId($appId)
     /**
      * {@inheritdoc}
      */
-    public function getMessageId()
+    public function getMessageId(): string
     {
         return $this->messageId;
     }
 
-    /**
-     * @param string $messageId
-     */
-    public function setMessageId($messageId)
+    public function setMessageId(string $messageId): void
     {
         $this->messageId = $messageId;
     }
@@ -303,15 +210,12 @@ public function setMessageId($messageId)
     /**
      * {@inheritdoc}
      */
-    public function getReplyTo()
+    public function getReplyTo(): string
     {
         return $this->replyTo;
     }
 
-    /**
-     * @param string $replyTo
-     */
-    public function setReplyTo($replyTo)
+    public function setReplyTo(string $replyTo): void
     {
         $this->replyTo = $replyTo;
     }
@@ -319,15 +223,12 @@ public function setReplyTo($replyTo)
     /**
      * {@inheritdoc}
      */
-    public function getCorrelationId()
+    public function getCorrelationId(): string
     {
         return $this->correlationId;
     }
 
-    /**
-     * @param string $correlationId
-     */
-    public function setCorrelationId($correlationId)
+    public function setCorrelationId(string $correlationId): void
     {
         $this->correlationId = $correlationId;
     }
@@ -335,7 +236,7 @@ public function setCorrelationId($correlationId)
     /**
      * {@inheritdoc}
      */
-    public function getHeaders()
+    public function getHeaders(): array
     {
         return $this->headers;
     }
@@ -343,7 +244,7 @@ public function getHeaders()
     /**
      * @param array $headers
      */
-    public function setHeaders($headers)
+    public function setHeaders(array $headers): void
     {
         $this->headers = $headers;
     }
@@ -351,8 +252,8 @@ public function setHeaders($headers)
     /**
      * {@inheritdoc}
      */
-    public function getHeader($headerKey)
+    public function getHeader(string $headerName): ?string
     {
-        return isset($this->headers[$headerKey]) ? $this->headers[$headerKey] : false;
+        return $this->headers[$headerName] ?? null;
     }
 }
diff --git a/src/AmqpBundle/Sandbox/NullQueue.php b/src/AmqpBundle/Sandbox/NullQueue.php
index d5a5d15..97b4f1f 100644
--- a/src/AmqpBundle/Sandbox/NullQueue.php
+++ b/src/AmqpBundle/Sandbox/NullQueue.php
@@ -35,19 +35,19 @@ public function enqueue(\AMQPEnvelope $envelope = null)
     /**
      * {@inheritdoc}
      */
-    public function get($flags = AMQP_NOPARAM)
+    public function get($flags = AMQP_NOPARAM): ?\AMQPEnvelope
     {
         if (!$this->envelopes->isEmpty()) {
             return $this->envelopes->dequeue();
-        } else {
-            return false;
         }
+
+        return null;
     }
 
     /**
      * {@inheritdoc}
      */
-    public function declareQueue()
+    public function declareQueue(): int
     {
         return $this->envelopes->count();
     }
diff --git a/src/AmqpBundle/Tests/Units/Amqp/Consumer.php b/src/AmqpBundle/Tests/Units/Amqp/Consumer.php
index 9360834..8965e50 100644
--- a/src/AmqpBundle/Tests/Units/Amqp/Consumer.php
+++ b/src/AmqpBundle/Tests/Units/Amqp/Consumer.php
@@ -26,8 +26,9 @@ public function testConstruct()
 
     public function testGetMessageAutoAck()
     {
+        $msgList = ['wait' => [1 => 'message1', '2' => 'message2']];
         $this
-            ->if($msgList = ['wait' => ['m1' => 'message1', 'm2' => 'message2']])
+            ->if($msgList)
             ->and($queue = $this->getQueue($msgList))
             ->and($consumer = new Base($queue, []))
                 // First message : auto ack
@@ -35,12 +36,12 @@ public function testGetMessageAutoAck()
                     ->isInstanceOf('\AMQPEnvelope')
                 ->string($message->getBody())
                     ->isEqualTo('message1')
-                ->string($message->getDeliveryTag())
-                    ->isEqualTo('m1')
+                ->integer($message->getDeliveryTag())
+                    ->isEqualTo(1)
                 ->array($msgList['wait'])
-                    ->isEqualTo(['m2' => 'message2'])
+                    ->isEqualTo([2 => 'message2'])
                 ->array($msgList['ack'])
-                    ->isEqualTo(['m1' => 'message1'])
+                    ->isEqualTo([1 => 'message1'])
                 ->array($msgList['unack'])
                     ->isEmpty()
 
@@ -49,12 +50,12 @@ public function testGetMessageAutoAck()
                     ->isInstanceOf('\AMQPEnvelope')
                 ->string($message->getBody())
                     ->isEqualTo('message2')
-                ->string($message->getDeliveryTag())
-                    ->isEqualTo('m2')
+                ->integer($message->getDeliveryTag())
+                    ->isEqualTo(2)
                 ->array($msgList['wait'])
                     ->isEmpty()
                 ->array($msgList['ack'])
-                    ->isEqualTo(['m1' => 'message1', 'm2' => 'message2'])
+                    ->isEqualTo([1 => 'message1', 2 => 'message2'])
                 ->array($msgList['unack'])
                     ->isEmpty()
 
@@ -71,7 +72,7 @@ public function testGetMessageAutoAck()
     public function testGetMessageManualAck()
     {
         $this
-            ->if($msgList = ['wait' => ['m1' => 'message1']])
+            ->if($msgList = ['wait' => [1 => 'message1']])
             ->and($queue = $this->getQueue($msgList))
             ->and($consumer = new Base($queue, []))
                 // First message : manual ack
@@ -79,58 +80,56 @@ public function testGetMessageManualAck()
                     ->isInstanceOf('\AMQPEnvelope')
                 ->string($message->getBody())
                     ->isEqualTo('message1')
-                ->string($message->getDeliveryTag())
-                    ->isEqualTo('m1')
+                ->integer($message->getDeliveryTag())
+                    ->isEqualTo(1)
 
                  // Check data
                 ->array($msgList['wait'])
                     ->isEmpty()
                 ->array($msgList['unack'])
-                    ->isEqualTo(['m1' => 'message1'])
+                    ->isEqualTo([1 => 'message1'])
                 ->array($msgList['ack'])
                     ->isEmpty()
 
                 // Ack (unknown delivery id)
-                ->boolean($message = $consumer->ackMessage(12345))
-                    ->isFalse()
-                ->mock($queue)
-                    ->call('ack')
-                        ->withArguments(12345)
-                        ->once()
+                ->and($message = $consumer->ackMessage(12345))
+                  ->variable($message)
+                  ->isNull()
+                  ->mock($queue)
+                      ->call('ack')
+                          ->withArguments(12345)
+                          ->once()
 
                 // Check data
                 ->array($msgList['wait'])
                     ->isEmpty()
                 ->array($msgList['unack'])
-                    ->isEqualTo(['m1' => 'message1'])
+                    ->isEqualTo([1 => 'message1'])
                 ->array($msgList['ack'])
                     ->isEmpty()
 
                 // Ack (known delivery id)
-                ->boolean($message = $consumer->ackMessage('m1'))
-                    ->isTrue()
-                ->mock($queue)
-                    ->call('ack')
-                        ->withArguments('m1')
-                        ->once()
+                ->and($message = $consumer->ackMessage(1))
+                  ->variable($message)
+                  ->isNull()
+                  ->mock($queue)
+                      ->call('ack')
+                          ->withArguments(1)
+                          ->once()
 
                  // Check data
                 ->array($msgList['wait'])
                     ->isEmpty()
                 ->array($msgList['ack'])
-                    ->isEqualTo(['m1' => 'message1'])
+                    ->isEqualTo([1 => 'message1'])
                 ->array($msgList['unack'])
-                    ->isEmpty()
-
-                // Ack (old delivery id)
-                ->boolean($message = $consumer->ackMessage('m1'))
-                    ->isFalse();
+                    ->isEmpty();
     }
 
     public function testGetMessageManualNack()
     {
         $this
-            ->if($msgList = ['wait' => ['m1' => 'message1']])
+            ->if($msgList = ['wait' => [1 => 'message1']])
             ->and($queue = $this->getQueue($msgList))
             ->and($consumer = new Base($queue, []))
                 // First message : manual ack
@@ -138,44 +137,46 @@ public function testGetMessageManualNack()
                     ->isInstanceOf('\AMQPEnvelope')
                 ->string($message->getBody())
                     ->isEqualTo('message1')
-                ->string($message->getDeliveryTag())
-                    ->isEqualTo('m1')
+                ->integer($message->getDeliveryTag())
+                    ->isEqualTo(1)
 
                  // Check data
                 ->array($msgList['wait'])
                     ->isEmpty()
                 ->array($msgList['unack'])
-                    ->isEqualTo(['m1' => 'message1'])
+                    ->isEqualTo([1 => 'message1'])
                 ->array($msgList['ack'])
                     ->isEmpty()
 
                 // Nack (unknown delivery id)
-                ->boolean($message = $consumer->nackMessage(12345))
-                    ->isFalse()
-                ->mock($queue)
-                    ->call('nack')
-                        ->withArguments(12345)
-                        ->once()
+                ->and($message = $consumer->nackMessage(12345))
+                  ->variable($message)
+                  ->isNull()
+                  ->mock($queue)
+                      ->call('nack')
+                          ->withArguments(12345)
+                          ->once()
 
                 // Check data
                 ->array($msgList['wait'])
                     ->isEmpty()
                 ->array($msgList['unack'])
-                    ->isEqualTo(['m1' => 'message1'])
+                    ->isEqualTo([1 => 'message1'])
                 ->array($msgList['ack'])
                     ->isEmpty()
 
                 // Nack and requeue (known delivery id)
-                ->boolean($message = $consumer->nackMessage('m1', AMQP_REQUEUE))
-                    ->isTrue()
-                ->mock($queue)
-                    ->call('nack')
-                        ->withArguments('m1')
-                        ->once()
+                ->and($message = $consumer->nackMessage(1, AMQP_REQUEUE))
+                  ->variable($message)
+                  ->isNull()
+                  ->mock($queue)
+                      ->call('nack')
+                          ->withArguments(1)
+                          ->once()
 
                  // Check data
                 ->array($msgList['wait'])
-                    ->isEqualTo(['m1' => 'message1'])
+                    ->isEqualTo([1 => 'message1'])
                 ->array($msgList['ack'])
                     ->isEmpty()
                 ->array($msgList['unack'])
@@ -186,20 +187,21 @@ public function testGetMessageManualNack()
                     ->isInstanceOf('\AMQPEnvelope')
                 ->string($message->getBody())
                     ->isEqualTo('message1')
-                ->string($message->getDeliveryTag())
-                    ->isEqualTo('m1')
+                ->integer($message->getDeliveryTag())
+                    ->isEqualTo(1)
 
                  // Check data
                 ->array($msgList['wait'])
                     ->isEmpty()
                 ->array($msgList['unack'])
-                    ->isEqualTo(['m1' => 'message1'])
+                    ->isEqualTo([1 => 'message1'])
                 ->array($msgList['ack'])
                     ->isEmpty()
 
                  // Nack and forget (known delivery id)
-                ->boolean($message = $consumer->nackMessage('m1'))
-                    ->isTrue()
+                ->and($message = $consumer->nackMessage(1))
+                    ->variable($message)
+                    ->isNull()
 
                 // Check data
                 ->array($msgList['wait'])
@@ -210,19 +212,19 @@ public function testGetMessageManualNack()
                     ->isEmpty()
 
                 // Nack (old delivery id)
-                ->boolean($message = $consumer->nackMessage('m1'))
-                    ->isFalse();
+                ->variable($message = $consumer->nackMessage(1))
+                    ->isEqualTo(null);
     }
 
     public function testPurge()
     {
         $this
-            ->if($msgList = ['wait' => ['m1' => 'message1']])
+            ->if($msgList = ['wait' => [1 => 'message1']])
             ->and($queue = $this->getQueue($msgList))
             ->and($consumer = new Base($queue, []))
                 // Purge the queue
-                ->boolean($consumer->purge())
-                    ->isTrue()
+                ->integer($consumer->purge())
+                    ->isEqualTo(1)
                 ->mock($queue)
                     ->call('purge')
                         ->once()
@@ -244,7 +246,7 @@ public function testGetMessageCurrentCount()
     {
         $this
             ->if($msgList = [
-                'wait' => ['m1' => 'message1', 'm2' => 'message2'],
+                'wait' => [1 => 'message1', 2 => 'message2'],
                 'flags' => AMQP_DURABLE | AMQP_EXCLUSIVE | AMQP_AUTODELETE,
             ])
             ->and($queue = $this->getQueue($msgList))
@@ -313,7 +315,8 @@ protected function getQueue(&$msgList = [])
             // Simulate a simple queue
             reset($msgList['wait']);
             $key = key($msgList['wait']);
-            $msg = array_shift($msgList['wait']);
+            $msg = reset($msgList['wait']);
+            unset($msgList['wait'][$key]);
 
             if (!$key) {
                 return null;
diff --git a/src/AmqpBundle/Tests/Units/Amqp/Producer.php b/src/AmqpBundle/Tests/Units/Amqp/Producer.php
index a5854d6..df6e346 100644
--- a/src/AmqpBundle/Tests/Units/Amqp/Producer.php
+++ b/src/AmqpBundle/Tests/Units/Amqp/Producer.php
@@ -72,8 +72,11 @@ public function testSendMessagesError()
             ->and($producer = new Base($exchange, $exchangeOptions))
                 ->boolean($producer->publishMessage('message1'))
                     ->isTrue()
-                ->boolean($producer->publishMessage('error'))
-                    ->isFalse()
+                ->exception(
+                  function() use($producer) {
+                    $producer->publishMessage('error');
+                  }
+                )->isInstanceOf(\AMQPExchangeException::class)
                 ->array($msgList)
                     ->isEqualTo([
                         ['message1', 'routing_test', AMQP_NOPARAM, $exchangeOptions['publish_attributes']],
@@ -182,7 +185,7 @@ protected function getExchange(&$msgList = [])
 
         $exchange->getMockController()->publish = function ($message, $routing_key, $flags = AMQP_NOPARAM, array $attributes = []) use (&$msgList) {
             if (($message == 'error') && ($routing_key == 'error')) {
-                return false;
+                throw new \AMQPExchangeException();
             }
 
             $msgList[] = [$message, $routing_key, $flags, $attributes];
diff --git a/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPChannel.php b/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPChannel.php
index 935d1ec..759cd4a 100644
--- a/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPChannel.php
+++ b/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPChannel.php
@@ -11,15 +11,15 @@ public function __construct(\AMQPConnection $amqp_connection)
     {
     }
 
-    public function qos($prefetchSize, $prefetchCount, $global = NULL)
+    public function qos(int $size, int $count, bool $global = NULL): void
     {
     }
 
-    public function setPrefetchSize($count){
-
+    public function setPrefetchSize(int $size): void
+    {
     }
 
-    public function setPrefetchCount($count){
-
+    public function setPrefetchCount(int $count): void
+    {
     }
 }
diff --git a/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPExchange.php b/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPExchange.php
index 04040b7..dc5917f 100644
--- a/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPExchange.php
+++ b/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPExchange.php
@@ -11,7 +11,7 @@ public function __construct(\AMQPChannel $amqp_channel)
     {
     }
 
-    public function declareExchange()
+    public function declareExchange(): void
     {
     }
 }
diff --git a/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPQueue.php b/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPQueue.php
index 9beb77f..a1d481a 100644
--- a/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPQueue.php
+++ b/src/AmqpBundle/Tests/Units/Factory/Mock/MockAMQPQueue.php
@@ -11,11 +11,12 @@ public function __construct(\AMQPChannel $amqp_channel)
     {
     }
 
-    public function bind($exchange_name, $routing_key = null, $arguments = array())
+    public function bind(string $exchange_name, string $routing_key = null, array $arguments = array()): void
     {
     }
 
-    public function declareQueue()
+    public function declareQueue(): int
     {
+        return 1;
     }
 }