'Check widget for dataset with missing values'

def test_missing_values(self):

    data = Table(Domain([DiscreteVariable('c1', [])]), np.array(([np.nan] * 6))[:, None])
    self.send_signal(self.widget.Inputs.data, data)
    attrs = [DiscreteVariable('c1', ['a', 'b', 'c'])]
    class_var = DiscreteVariable('cls', [])
    X = np.array([1, 2, 0, 1, 0, 2])[:, None]
    data = Table(Domain(attrs, class_var), X, np.array(([np.nan] * 6)))
    self.send_signal(self.widget.Inputs.data, data)
