如何测试Python数独类

import unittest
from sudoku import Sudoku

class SudokuTest(unittest.TestCase):
    def test_solved_sudoku(self):
        # 已经解决的数独
        puzzle = [
            [5, 3, 4, 6, 7, 8, 9, 1, 2],
            [6, 7, 2, 1, 9, 5, 3, 4, 8],
            [1, 9, 8, 3, 4, 2, 5, 6, 7],
            [8, 5, 9, 7, 6, 1, 4, 2, 3],
            [4, 2, 6, 8, 5, 3, 7, 9, 1],
            [7, 1, 3, 9, 2, 4, 8, 5, 6],
            [9, 6, 1, 5, 3, 7, 2, 8, 4],
            [2, 8, 7, 4, 1, 9, 6, 3, 5],
            [3, 4, 5, 2, 8, 6, 1, 7, 9]
        ]
        expected_solution = puzzle  # 已经解决的数独结果是其本身

        sudoku = Sudoku(puzzle)
        solution = sudoku.solve()

        self.assertEqual(solution, expected_solution)

    def test_unsolved_sudoku(self):
        # 未解决的数独
        puzzle = [
            [5, 3, 0, 0, 7, 0, 0, 0, 0],
            [6, 0, 0, 1, 9, 5, 0, 0, 0],
            [0, 9, 8, 0, 0, 0, 0, 6, 0],
            [8, 0, 0, 0, 6, 0, 0, 0, 3],
            [4, 0, 0, 8, 0, 3, 0, 0, 1],
            [7, 0, 0, 0, 2, 0, 0, 0, 6],
            [0, 6, 0, 0, 0, 0, 2, 8, 0],
            [0, 0, 0, 4, 1, 9, 0, 0, 5],
            [0, 0, 0, 0, 8, 0, 0, 7, 9]
        ]
        expected_solution = [
            [5, 3, 4, 6, 7, 8, 9, 1, 2],
            [6, 7, 2, 1, 9, 5, 3, 4, 8],
            [1, 9, 8, 3, 4, 2, 5, 6, 7],
            [8, 5, 9, 7, 6, 1, 4, 2, 3],
            [4, 2, 6, 8, 5, 3, 7, 9, 1],
            [7, 1, 3, 9, 2, 4, 8, 5, 6],
            [9, 6, 1, 5, 3, 7, 2, 8, 4],
            [2, 8, 7, 4, 1, 9, 6, 3, 5],
            [3, 4, 5, 2, 8, 6, 1, 7, 9]
        ]

        sudoku = Sudoku(puzzle)
        solution = sudoku.solve()

        self.assertEqual(solution, expected_solution)

    def test_invalid_sudoku(self):
        # 无解的数独
        puzzle = [
            [5, 3, 4, 6, 7, 8, 9, 1, 2],
            [6, 7, 2, 1, 9, 5, 3, 4, 8],
            [1, 9, 8, 3, 4, 2, 5, 6, 7],
            [8, 5, 9, 7, 6, 1, 4, 2, 3],
            [4, 2, 6, 8, 5, 3, 7, 9, 1],
            [7, 1, 3, 9, 2, 4, 8, 5, 6],
            [9, 6, 1, 5, 3, 7, 2, 8, 4],
            [2, 8, 7, 4, 1, 9, 6, 3, 5],
            [3, 4, 5, 2, 8, 6, 0, 7, 9]  # 最后一行缺少一个数字
        ]

        sudoku = Sudoku(puzzle)
        solution = sudoku.solve()

        self.assertIsNone(solution)  # 无解的数独返回None

if __name__ == '__main__':
    unittest.main()