def test_invalidWithInvariant(self):
        """
        Creating a L{base.PositionError} with values set to an impossible
        combination raises C{ValueError} if the invariant is being tested.
        """
        self.assertRaises(ValueError, base.PositionError,
                          pdop=1.0, vdop=1.0, hdop=1.0, testInvariant=True)

        Creating a L{base.PositionError} with values set to an impossible
        combination raises C{ValueError} if the invariant is being tested.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/positioning/test/test_base.py