title: Unstubbing a class method in Mocha
body: <p>For a particular test, I want to change the return value of a class method.</p>
  
  <p>I can get the correct behavior by calling MyClass.expects(:method).returns(:myvalue). How can I <em>stop</em> this behavior once I'm done with the test?</p>
  
  <p>There's an <code>unstub</code> method in Mocha, but it appears to only work on instance methods, not class methods.</p>