'Check widget for multiclass dataset'

def test_multiclass(self):

    attrs = [ContinuousVariable('c1'), ContinuousVariable('c2')]
    class_vars = [DiscreteVariable('cls', ['a', 'b', 'c']), DiscreteVariable('cls', ['aa', 'bb', 'cc'])]
    domain = Domain(attrs, class_vars)
    X = np.arange(12).reshape(6, 2)
    Y = np.array([[0, 1], [2, 1], [0, 2], [1, 1], [1, 2], [2, 0]])
    data = Table(domain, X, Y)
    self.send_signal(self.widget.Inputs.data, data)
    self.assertTrue(self.widget.Error.multiclass_error.is_shown())
    self.send_signal(self.widget.Inputs.data, None)
    self.assertFalse(self.widget.Error.multiclass_error.is_shown())
