title: behat / mink: using phpunit mock in context
body: <p>I cannot find a way to use a phpunit mock in a behat context.</p>
  
  <p>My FeatureContext cannot extend <code>PHPUnit_Framework_TestCase</code> because it already extends <code>MinkContext</code>.</p>
  
  <p>I tried to have it implement <code>PHPUnit_Framework_MockObject_MockObject</code> but I got the fatal error that it should implement the 5 abstract methods.</p>
  
  <p>I tried with the static call to <code>PHPUnit_Framework_TestCase</code> inside a FeatureContext method (where I need the mock) but then I got this error <code>Non-static method PHPUnit_Framework_TestCase::getMockBuilder() should not be called statically, assuming $this from incompatible context in features/bootstrap/FeatureContext.php</code>.</p>
  
  <p>Any idea how I could achieve this?</p>