title: mocking in TestCase.setUp()
body: <p>I want to mock all test methods of a <code>TestCase</code>.</p>
  
  <p>My first try to use <code>TestCase.setUp()</code> did not work, since <code>setUp()</code> finishes before the test methods gets executed.</p>
  
  <p>I can't mock the real test method with this inside <code>setUp()</code>:</p>
  
  <pre><code>with mock.patch(...):
      do_something()
  </code></pre>
  
  <p>I guess I am missing something.</p>
  
  <p>How to use <code>mock.patch()</code> for all methods of a test case?</p>