title: Assert a function/method was not called using Mock
body: <p>I'm using the Mock library to test my application, but I want to assert that some function was not called. Mock docs talk about methods like <code>mock.assert_called_with</code> and <code>mock.assert_called_once_with</code>, but I didn't find anything like <code>mock.assert_not_called</code> or something related to verify mock was <strong>NOT called</strong>.</p>
  
  <p>I could go with something like the following, though it doesn't seem cool nor pythonic:</p>
  
  <pre><code>def test_something:
      # some actions
      with patch('something') as my_var:
          try:
              # args are not important. func should never be called in this test
              my_var.assert_called_with(some, args)
          except AssertionError:
              pass  # this error being raised means it's ok
      # other stuff
  </code></pre>
  
  <p>Any ideas how to accomplish this?</p>