'On regression data, the widget must show error'

def test_show_error_on_regression(self):

    housing = Table('housing')
    results = TestOnTrainingData(housing, [MeanLearner()], store_data=True)
    self.send_signal(self.widget.Inputs.evaluation_results, results)
    self.assertTrue(self.widget.Error.no_regression.is_shown())
    self.send_signal(self.widget.Inputs.evaluation_results, None)
    self.assertFalse(self.widget.Error.no_regression.is_shown())
    self.send_signal(self.widget.Inputs.evaluation_results, results)
    self.assertTrue(self.widget.Error.no_regression.is_shown())
    self.send_signal(self.widget.Inputs.evaluation_results, self.results_1_iris)
    self.assertFalse(self.widget.Error.no_regression.is_shown())
