':func:`validate_signature_against_kwargs` raises an
``InvalidSignature`` exception if a function that has *args but no
**kwargs is called with keyword arguments beyond the specified
arguments.'

def test_args_fun_failure(self):

    self.assertThat((lambda : validate_signature_against_kwargs(_args_fun, set(['one', 'unexpected']))), _raises_invalid_signature(unexpected_arguments=set(['unexpected'])))
