binary_search_tree_test.py

# These tests are auto-generated with test data from:
# https://github.com/exercism/problem-specifications/tree/main/exercises/binary-search-tree/canonical-data.json
# File last updated on 2023-07-20

import unittest

from binary_search_tree import (
    BinarySearchTree,
    TreeNode,
)


class BinarySearchTreeTest(unittest.TestCase):
    def test_data_is_retained(self):
        expected = TreeNode("4", None, None)
        self.assertTreeEqual(BinarySearchTree(["4"]).data(), expected)

    def test_smaller_number_at_left_node(self):
        expected = TreeNode("4", TreeNode("2", None, None), None)
        self.assertTreeEqual(BinarySearchTree(["4", "2"]).data(), expected)

    def test_same_number_at_left_node(self):
        expected = TreeNode("4", TreeNode("4", None, None), None)
        self.assertTreeEqual(BinarySearchTree(["4", "4"]).data(), expected)

    def test_greater_number_at_right_node(self):
        expected = TreeNode("4", None, TreeNode("5", None, None))
        self.assertTreeEqual(BinarySearchTree(["4", "5"]).data(), expected)

    def test_can_create_complex_tree(self):
        expected = TreeNode(
            "4",
            TreeNode("2", TreeNode("1", None, None), TreeNode("3", None, None)),
            TreeNode("6", TreeNode("5", None, None), TreeNode("7", None, None)),
        )
        self.assertTreeEqual(
            BinarySearchTree(["4", "2", "6", "1", "3", "5", "7"]).data(), expected
        )

    def test_can_sort_single_number(self):
        expected = ["2"]
        self.assertEqual(BinarySearchTree(["2"]).sorted_data(), expected)

    def test_can_sort_if_second_number_is_smaller_than_first(self):
        expected = ["1", "2"]
        self.assertEqual(BinarySearchTree(["2", "1"]).sorted_data(), expected)

    def test_can_sort_if_second_number_is_same_as_first(self):
        expected = ["2", "2"]
        self.assertEqual(BinarySearchTree(["2", "2"]).sorted_data(), expected)

    def test_can_sort_if_second_number_is_greater_than_first(self):
        expected = ["2", "3"]
        self.assertEqual(BinarySearchTree(["2", "3"]).sorted_data(), expected)

    def test_can_sort_complex_tree(self):
        expected = ["1", "2", "3", "5", "6", "7"]
        self.assertEqual(
            BinarySearchTree(["2", "1", "3", "6", "7", "5"]).sorted_data(), expected
        )

    # Utilities
    def assertTreeEqual(self, tree_one, tree_two):
        try:
            self.compare_tree(tree_one, tree_two)
        except AssertionError:
            raise AssertionError("{} != {}".format(tree_one, tree_two))

    def compare_tree(self, tree_one, tree_two):
        self.assertEqual(tree_one.data, tree_two.data)

        # Compare left tree nodes
        if tree_one.left and tree_two.left:
            self.compare_tree(tree_one.left, tree_two.left)
        elif tree_one.left is None and tree_two.left is None:
            pass
        else:
            raise AssertionError

        # Compare right tree nodes
        if tree_one.right and tree_two.right:
            self.compare_tree(tree_one.right, tree_two.right)
        elif tree_one.right is None and tree_two.right is None:
            pass
        else:
            raise AssertionError