def test_gini_impurity_min(self):
        """Test minimum gini impurity.

        Asserts:
            entropy is 0.
        """

        gini_impurity = dt.gini_impurity([1, 1, 1, 1, 1, 1])

        assert 0 == round(gini_impurity, 3)
    def test_gini_impurity(self):
        """Test gini impurity.

        Asserts:
            gini impurity is matched as expected.
        """

        gini_impurity = dt.gini_impurity([1, 1, 0, 0, 0, 0])

        assert round(4. / 9., 3) == round(gini_impurity, 3)
    def test_gini_impurity_max(self):
        """Test maximum gini impurity.

        Asserts:
            gini impurity is 0.5.
        """

        gini_impurity = dt.gini_impurity([1, 1, 1, 0, 0, 0])

        assert .500 == round(gini_impurity, 3)