title: pytest fixture yield returns generator instead of object
body: <p>I'm running pytest-3. I'm defining a fixture that is supposed to return a falcon TestClient object. I also need a teardown, so I'm trying to yield it.</p>
  
  <pre><code>def client():
      api=create_app()
      c = testing.TestClient(api)
      yield c
      remove_db()
  </code></pre>
  
  <p>If I 'return' instead of 'yield', the test cases run just fine.
  But with yield, my test cases get a generator object instead of a TestClient object</p>