fixture single upload

Author: samsonasik

spec/Handler/Writer/MailSpec.php

@@ -24,7 +24,7 @@
                 'body_data'      => ['text' => 'test'],
                 'raw_data'       => [],
                 'files_data'     => [
-                    [
+                    "fileupload" => [
                         'name' => 'foo.html',
                         'tmp_name' => __DIR__ . '/../../Fixture/data/foo.html',
                         'error'    => 0,