'Check if error message appears and then disappears when
data is removed from input'

def test_error_message(self):

    self.send_signal(self.widget.Inputs.data, self.iris)
    self.assertFalse(self.widget.Error.no_continuous_features.is_shown())
    self.send_signal(self.widget.Inputs.data, self.titanic)
    self.assertTrue(self.widget.Error.no_continuous_features.is_shown())
    self.send_signal(self.widget.Inputs.data, None)
    self.assertFalse(self.widget.Error.no_continuous_features.is_shown())
