import unittest


class TestBstValidate(unittest.TestCase):

    def test_bst_validate_empty(self):
        bst = BstValidate(None)
        bst.validate()

    def test_bst_validate(self):
        bst = BstValidate(Node(5))
        bst.insert(8)
        bst.insert(5)
        bst.insert(6)
        bst.insert(4)
        bst.insert(7)
        self.assertEqual(bst.validate(), True)

        bst = BstValidate(Node(5))
        left = Node(5)
        right = Node(8)
        invalid = Node(20)
        bst.root.left = left
        bst.root.right = right
        bst.root.left.right = invalid
        self.assertEqual(bst.validate(), False)

        print('Success: test_bst_validate')


def main():
    test = TestBstValidate()
    test.assertRaises(TypeError, test.test_bst_validate_empty)
    test.test_bst_validate()


if __name__ == '__main__':
    main()