title: py.test doesn't collect tests that are not inherited from 'object'
body: <p>I'm trying to create <strong>Base</strong> class with different setups I need for my tests. I want all my tests to be inherited from this <strong>Base</strong> class. As runner I use <a href="http://pytest.org" rel="noreferrer">py.test</a>. </p>
  
  <p>But when I'm trying to do so, py.test doesn't collect these tests inherited from <strong>Base</strong> class, and as a result it doesn't run them. Didn't find any useful info in documentation. </p>
  
  <p>Maybe someone faced such issues before? Any ideas?</p>
  
  <p>Thanks. </p>
  
  <p>P.S. When tests are inherited from <strong>object</strong> everything works fine. Py.test see them and run correctly.</p>
  
  <p>Example of code:</p>
  
  <p>My Base class:</p>
  
  <pre><code>class BaseClass(object):
  """BaseClass"""
  def __init__(self):
      super(BaseClass, self).__init__()
      self.bla = 'bla'
  </code></pre>
  
  <p>My Test class:</p>
  
  <pre><code>import pytest
  from base_class import BaseClass
  
  class TestSmth(BaseClass):
      def test_test(self):
          test_instatnce = TestSmth()
          print test_instatnce.bla
  
  if __name__ == '__main__':
      pytest.main([__file__, '-v'])
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>============================= test session starts ==============================
  platform darwin -- Python 2.7.2 -- pytest-2.3.3 -- /usr/bin/python
  collecting ... collected 0 items
  
  ===============================  in 0.01 seconds ===============================
  [Finished in 0.4s]  
  </code></pre>