diff --git a/src/TestEnvelope.php b/src/TestEnvelope.php
index 6b3b6b7..ca6e68f 100644
--- a/src/TestEnvelope.php
+++ b/src/TestEnvelope.php
@@ -22,7 +22,7 @@
  */
 final class TestEnvelope
 {
-    public function __construct(private Envelope $envelope)
+    public function __construct(public readonly Envelope $envelope)
     {
     }
 
diff --git a/src/Transport/TestTransport.php b/src/Transport/TestTransport.php
index 2efd914..f7a790c 100644
--- a/src/Transport/TestTransport.php
+++ b/src/Transport/TestTransport.php
@@ -20,16 +20,19 @@
 use Symfony\Component\Messenger\MessageBusInterface;
 use Symfony\Component\Messenger\Stamp\DelayStamp;
 use Symfony\Component\Messenger\Stamp\RedeliveryStamp;
+use Symfony\Component\Messenger\Transport\Receiver\ListableReceiverInterface;
+use Symfony\Component\Messenger\Transport\Receiver\MessageCountAwareInterface;
 use Symfony\Component\Messenger\Transport\Serialization\SerializerInterface;
 use Symfony\Component\Messenger\Transport\TransportInterface;
 use Symfony\Component\Messenger\Worker;
 use Zenstruck\Assert;
 use Zenstruck\Messenger\Test\Stamp\AvailableAtStamp;
+use Zenstruck\Messenger\Test\TestEnvelope;
 
 /**
  * @author Kevin Bond <kevinbond@gmail.com>
  */
-final class TestTransport implements TransportInterface
+final class TestTransport implements TransportInterface, ListableReceiverInterface, MessageCountAwareInterface
 {
     private const DEFAULT_OPTIONS = [
         'intercept' => true,
@@ -279,6 +282,24 @@ public function reject(Envelope $envelope): void
         $this->collectMessage(self::$rejected, $envelope);
     }
 
+    public function all(?int $limit = null): iterable
+    {
+        return \array_map(
+            fn(TestEnvelope $envelope) => $envelope->envelope,
+            \array_slice($this->queue()->all(), 0, $limit),
+        );
+    }
+
+    public function find(mixed $id): ?Envelope
+    {
+        throw new \BadMethodCallException('Not supported.');
+    }
+
+    public function getMessageCount(): int
+    {
+        return $this->queue()->count();
+    }
+
     /**
      * @param Envelope|object|array{headers?:mixed[],body:string} $what object: will be wrapped in envelope
      *                                                                  array: will be decoded into envelope
diff --git a/tests/InteractsWithMessengerTest.php b/tests/InteractsWithMessengerTest.php
index 997b371..655d9e7 100644
--- a/tests/InteractsWithMessengerTest.php
+++ b/tests/InteractsWithMessengerTest.php
@@ -917,6 +917,52 @@ public function process_empty_queue(): void
         ;
     }
 
+    /**
+     * @test
+     */
+    public function transport_is_message_count_aware(): void
+    {
+        self::getContainer()->get(MessageBusInterface::class)->dispatch(new MessageA());
+        self::getContainer()->get(MessageBusInterface::class)->dispatch(new MessageA());
+
+        $this->assertSame(2, $this->transport()->getMessageCount());
+
+        $this->transport()->process();
+
+        $this->assertSame(0, $this->transport()->getMessageCount());
+    }
+
+    /**
+     * @test
+     */
+    public function transport_is_listable(): void
+    {
+        self::getContainer()->get(MessageBusInterface::class)->dispatch($msgA = new MessageA());
+        self::getContainer()->get(MessageBusInterface::class)->dispatch($msgB = new MessageB());
+
+        $messages = \array_map(fn(Envelope $e) => $e->getMessage(), $this->transport()->all());
+
+        $this->assertSame([$msgA, $msgB], $messages);
+
+        $messages = \array_map(fn(Envelope $e) => $e->getMessage(), $this->transport()->all(1));
+
+        $this->assertSame([$msgA], $messages);
+
+        $this->transport()->process();
+
+        $this->assertEmpty($this->transport()->all());
+    }
+
+    /**
+     * @test
+     */
+    public function cannot_use_find_on_transport(): void
+    {
+        $this->expectException(\BadMethodCallException::class);
+
+        $this->transport()->find(1);
+    }
+
     protected static function bootKernel(array $options = []): KernelInterface // @phpstan-ignore-line
     {
         return parent::bootKernel(\array_merge(['environment' => 'single_transport'], $options));