Ensures preceding predicates (specifically, :meth:`called_with()`) result in *expected_exception* being raised.

def raises(self, expected_exception):
        """
        Ensures preceding predicates (specifically, :meth:`called_with()`) result in *expected_exception* being raised.
        """
        return unittest_case.assertRaises(expected_exception, self._orig_subject, *self._args, **self._kwargs)