From 561f9b734536f02f41d4cd6ffd14d32387d2455f Mon Sep 17 00:00:00 2001
From: Fabien Potencier <fabien@potencier.org>
Date: Mon, 2 Sep 2019 17:31:45 +0200
Subject: [PATCH] [Mailer] Add a more precise exception

---
 .../Mailer/Tests/Transport/TransportsTest.php    | 16 ++++++++++++++++
 .../Component/Mailer/Transport/Transports.php    |  2 +-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/Symfony/Component/Mailer/Tests/Transport/TransportsTest.php b/src/Symfony/Component/Mailer/Tests/Transport/TransportsTest.php
index 93f6dee9f5..10d46ca846 100644
--- a/src/Symfony/Component/Mailer/Tests/Transport/TransportsTest.php
+++ b/src/Symfony/Component/Mailer/Tests/Transport/TransportsTest.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\Mailer\Tests\Transport;
 
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\Mailer\Exception\InvalidArgumentException;
 use Symfony\Component\Mailer\Transport\TransportInterface;
 use Symfony\Component\Mailer\Transport\Transports;
 use Symfony\Component\Mime\Header\Headers;
@@ -48,4 +49,19 @@ class TransportsTest extends TestCase
         $email = new Message($headers, new TextPart('...'));
         $transport->send($email);
     }
+
+    public function testTransportDoesNotExist()
+    {
+        $transport = new Transports([
+            'foo' => $this->createMock(TransportInterface::class),
+            'bar' => $this->createMock(TransportInterface::class),
+        ]);
+
+        $headers = (new Headers())->addTextHeader('X-Transport', 'foobar');
+        $email = new Message($headers, new TextPart('...'));
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('The "foobar" transport does not exist (available transports: "foo", "bar").');
+        $transport->send($email);
+    }
 }
diff --git a/src/Symfony/Component/Mailer/Transport/Transports.php b/src/Symfony/Component/Mailer/Transport/Transports.php
index 0158d2a1f8..983ad15018 100644
--- a/src/Symfony/Component/Mailer/Transport/Transports.php
+++ b/src/Symfony/Component/Mailer/Transport/Transports.php
@@ -56,7 +56,7 @@ class Transports implements TransportInterface
         $headers->remove('X-Transport');
 
         if (!isset($this->transports[$transport])) {
-            throw new InvalidArgumentException(sprintf('The "%s" transport does not exist.', $transport));
+            throw new InvalidArgumentException(sprintf('The "%s" transport does not exist (available transports: "%s").', $transport, implode('", "', array_keys($this->transports))));
         }
 
         return $this->transports[$transport]->send($message, $envelope);