title: pytest - add assertions to all or marked test functions
body: <p>I have common assertions performed on a fixture (named <code>obj</code> here) at the end of most test functions, like:
  </p>
  
  <pre><code>assert obj.is_empty
  assert obj.no_errors
  </code></pre>
  
  <p>How can I append such steps to each test function or only marked ones so that, steps:</p>
  
  <ul>
  <li>will work with <code>pytest.mark.parametrize</code>,</li>
  <li>will report <strong>Failure</strong> (not <strong>Error</strong>) when common assertions fail?</li>
  </ul>