Make Mailer macroable (#18763)

Author: adamwathan

src/Illuminate/Mail/Mailer.php

@@ -6,6 +6,7 @@
 use Illuminate\Support\Arr;
 use InvalidArgumentException;
 use Illuminate\Contracts\View\Factory;
+use Illuminate\Support\Traits\Macroable;
 use Illuminate\Contracts\Support\Htmlable;
 use Illuminate\Contracts\Events\Dispatcher;
 use Illuminate\Contracts\Queue\ShouldQueue;
@@ -16,6 +17,8 @@
 
 class Mailer implements MailerContract, MailQueueContract
 {
+    use Macroable;
+
     /**
      * The view factory instance.
      *

tests/Mail/MailMailerTest.php

@@ -3,6 +3,7 @@
 namespace Illuminate\Tests\Mail;
 
 use Mockery as m;
+use Illuminate\Mail\Mailer;
 use PHPUnit\Framework\TestCase;
 use Illuminate\Support\HtmlString;
 
@@ -148,9 +149,22 @@ public function testEventsAreDispatched()
         });
     }
 
+    public function testMacroable()
+    {
+        Mailer::macro('foo', function () {
+            return 'bar';
+        });
+
+        $mailer = $this->getMailer();
+
+        $this->assertEquals(
+            'bar', $mailer->foo()
+        );
+    }
+
     protected function getMailer($events = null)
     {
-        return new \Illuminate\Mail\Mailer(m::mock('Illuminate\Contracts\View\Factory'), m::mock('Swift_Mailer'), $events);
+        return new Mailer(m::mock('Illuminate\Contracts\View\Factory'), m::mock('Swift_Mailer'), $events);
     }
 
     public function setSwiftMailer($mailer)