Add test for html only notifications

tests/Integration/Notifications/SendingMailNotificationsTest.php

@@ -249,7 +249,7 @@ public function testMailIsSentUsingMailable()
         $user->notify($notification);
     }
 
-    public function testMailIsSentUsingMailMessageWithPlain()
+    public function testMailIsSentUsingMailMessageWithHtmlAndPlain()
     {
         $notification = new TestMailNotificationWithPlain;
         $notification->id = Str::uuid()->toString();
@@ -280,6 +280,38 @@ public function testMailIsSentUsingMailMessageWithPlain()
 
         $user->notify($notification);
     }
+
+    public function testMailIsSentUsingMailMessageWithHtmlOnly()
+    {
+        $notification = new TestMailNotificationWithHtmlOnly;
+        $notification->id = Str::uuid()->toString();
+
+        $user = NotifiableUser::forceCreate([
+            'email' => 'taylor@laravel.com',
+        ]);
+
+        $this->mailer->shouldReceive('send')->once()->with(
+            ['html' => 'html', 'text' => null],
+            array_merge($notification->toMail($user)->toArray(), [
+                '__laravel_notification_id' => $notification->id,
+                '__laravel_notification' => get_class($notification),
+                '__laravel_notification_queued' => false,
+            ]),
+            m::on(function ($closure) {
+                $message = m::mock(Message::class);
+
+                $message->shouldReceive('to')->once()->with(['taylor@laravel.com']);
+
+                $message->shouldReceive('subject')->once()->with('Test Mail Notification With Html Only');
+
+                $closure($message);
+
+                return true;
+            })
+        );
+
+        $user->notify($notification);
+    }
 }
 
 class NotifiableUser extends Model
@@ -378,3 +410,18 @@ public function toMail($notifiable)
             ->text('plain');
     }
 }
+
+class TestMailNotificationWithHtmlOnly extends Notification
+{
+    public function via($notifiable)
+    {
+        return [MailChannel::class];
+    }
+
+    public function toMail($notifiable)
+    {
+        return (new MailMessage)
+            ->view('html')
+            ->text(null);
+    }
+}