 <p>It's actually not so hard to get this to work. It's a bit hacky since you are adding code to the engine's routes.rb file that changes depending on which env it's running in. If you are using the spec/dummy <a href="http://reinteractive.net/posts/2-start-your-engines" rel="nofollow">site approach</a> for testing the engine then use the following code snippet in /config/routes.rb file:</p> <pre><code># &lt;your_engine&gt;/config/routes.rb if Rails.env.test? &amp;&amp; Rails.application.class.name.to_s == 'Dummy::Application' application = Rails.application else application = YourEngine::Engine end application.routes.draw do ... end </code></pre> <p>What this is basically doing is switching out your engine for the dummy app and writing the routes to it when in test mode.</p>