Test to prove tighten#81 was actually fixed!

composer.json

@@ -24,7 +24,8 @@
     },
     "autoload-dev": {
         "classmap": [
-            "tests/TestCase.php"
+            "tests/TestCase.php",
+            "tests/AppStub.php"
         ]
     }
 }

tests/AppStub.php

@@ -0,0 +1,43 @@
+<?php
+
+class AppStub extends \Illuminate\Foundation\Application implements \ArrayAccess
+{
+    private $foo;
+    private $mailer;
+    protected $attributes = [];
+
+    public function setAttributes($attributes)
+    {
+        $this->attributes = $attributes;
+    }
+
+    public function version()
+    {
+        return 5.4;
+    }
+
+    public function instance($key, $instance)
+    {
+        $this->attributes[$key] = $instance;
+    }
+
+    public function offsetExists($offset)
+    {
+        return isset($this->attributes[$offset]);
+    }
+
+    public function offsetGet($key)
+    {
+        return $this->attributes[$key];
+    }
+
+    public function offsetSet($key, $value)
+    {
+        $this->attributes[$key] = $value;
+    }
+
+    public function offsetUnset($key)
+    {
+        unset($this->attributes[$key]);
+    }
+}

tests/MailFacadeIntegrationTest.php

@@ -0,0 +1,41 @@
+<?php
+
+use Illuminate\Support\Facades\Facade;
+use Illuminate\Support\Facades\Mail;
+use MailThief\Facades\MailThief;
+use MailThief\Testing\InteractsWithMail;
+use MailThief\MailThiefFiveFourCompatible;
+
+class MailFacadeIntegrationTest extends TestCase
+{
+    use InteractsWithMail;
+
+    public function setUp()
+    {
+        $app = new AppStub;
+        $app->setAttributes([
+            MailThiefFiveFourCompatible::class => $this->getMailThief(),
+        ]);
+
+        Facade::setFacadeApplication($app);
+
+        parent::setUp();
+    }
+
+    public function test_previously_set_instance_of_mailthief_doesnt_change()
+    {
+        Mail::send('example-view', [], function ($m) {
+            $m->to('[email protected]');
+        });
+
+        $this->seeMessageFor('[email protected]');
+
+        MailThief::swap($this->getMailThief());
+
+        Mail::send('example-view', [], function ($m) {
+            $m->to('[email protected]');
+        });
+
+        $this->seeMessageFor('[email protected]');
+    }
+}