title: pytest monkeypatch.setattr() inside of test class method
body: <p>I have a test class with few test methods and I want to patch some app classes and methods from the test methods. 
  In pytest docs I found <a href="http://doc.pytest.org/en/latest/monkeypatch.html#simple-example-monkeypatching-functions" rel="noreferrer">an example</a> of how to use monkeypatch module for tests. It that example all tests are just functions, not testclass methods.</p>
  
  <p>But I have a class with test methods:</p>
  
  <pre><code>class MyTest(TestCase):
     def setUp():
       pass
  
     def test_classmethod(self, monkeypatch):
       # here I want to use monkeypatch.setattr()
       pass
  </code></pre>
  
  <p>And just passing <code>monkeypatch</code> as method param is obviously doesn't work. So looks like py.test magic doesn't work this way. </p>
  
  <p>So the question is simple and maybe stupid: how can I use  <code>monkeypatch.setattr()</code> for pytest inside from the test class method?</p>