title: Python unit testing interfaces
body: <p>This is an extension of: <a href="https://stackoverflow.com/questions/2915286/unit-testing-interfaces-in-python">Unit Testing Interfaces in Python</a></p>
  
  <p>My problem is the number of classes that satisfy an interface will eventually run into the thousands. Different developers work on different sub classes.</p>
  
  <p>We can't have a failing unit test for one subclass fail tests for other sub classes. Essentially, I need to create a new unittest.TestCase type for each subclass satisfying the interface.</p>
  
  <p>It would be nice to be able to do this without having to modify the test module. (I'd like to avoid updating the unit test module every time a new subclass satisfying the interface is added). </p>
  
  <p>I want to be able to create a unittest.TestCase class type automatically for a class satisfying interface. This can be done using meta classes. </p>
  
  <p>But these classes need to be added to the test module for testing. Can this be done during class definition without requiring modifications to the test module?</p>