Add config file.

I forgot this like a noob.

tests/test_app/invalid_routes/routes.php

@@ -0,0 +1,7 @@
+<?php
+/**
+ * Test routes file with routes that trigger a missing route class error.
+ * Application requests should have InvalidArgument error rendered.
+ */
+$routes->setRouteClass('DoesNotExist');
+$routes->get('/', ['controller' => 'Pages']);