title: Can I run a Rails engine's specs from a real app which mounts it?
body: <p>I have a Rails Engine meant to provide some models and controllers to a larger project of ours. There's a pretty decent set of specs for the Engine, using a bunch of mocks and some full-scale models and controllers within the engine's dummy app to make sure the Engine is doing what it's supposed to and working with the larger application.</p>
  
  <p>However, even with all tests passing, I frequently find broken behavior when I update the engine in the larger application. If my tests are passing but the behavior is broken, clearly something's wrong with the tests, but what? Am I mocking too much, or not enough?</p>
  
  <p>To get me closer to figuring this out, I'd like to be able to run the engine's tests from inside the full application. This seems like it should be possible, but I don't understand rspec thoroughly enough to get a handle on how.</p>
  
  <p>(This is related to <a href="https://stackoverflow.com/q/9655874/306084">this question</a> but not quite the same; I'm not trying to run all the specs from one command, just to run the engine's specs within the full app environment. <a href="https://stackoverflow.com/q/6587413/306084">This</a> also seems to be related. Actually, I've read every question tagged with both <a href="/questions/tagged/rspec" class="post-tag" title="show questions tagged &#39;rspec&#39;" rel="tag">rspec</a> and <a href="/questions/tagged/rails-engines" class="post-tag" title="show questions tagged &#39;rails-engines&#39;" rel="tag">rails-engines</a>--there aren't many--and they're all either not what I need, or unanswered.)</p>