python - Python UnitTest 中的 assertEqual 应该做什么？

Question

assertEqual(a, b) 检查是否 a == b 并返回 True 或 False，

文档说，

Test that first and second are equal. If the values do not compare equal, the test will fail.

我在一个简单的类上使用 assertEqual 运行三个测试，

测试类

class Car:
    def __init__(self, name):
        self.name = name

测试用例

class CarTest(unittest.TestCase):

    def test_diff_equal(self):
        car1 = Car('Ford')
        car2 = Car('Hyundai')
        self.assertEqual(car1, car2)

    def test_name_equal(self):
        car1 = Car('Ford')
        car2 = Car('Ford')
        self.assertEqual(car1, car2)

    def test_instance_equal(self):
        car1 = Car('Ford')
        self.assertEqual(car1, car1)

结果是

F.F
======================================================================
FAIL: test_diff_equal (cartest.CarTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "cartest.py", line 10, in test_diff_equal
    self.assertEqual(car1, car2)
AssertionError: <car.Car instance at 0x7f499ec12ef0> != <car.Car instance at 0x7f499ec12f38>

======================================================================
FAIL: test_name_equal (cartest.CarTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "cartest.py", line 15, in test_name_equal
    self.assertEqual(car1, car2)
AssertionError: <car.Car instance at 0x7f499ec12fc8> != <car.Car instance at 0x7f499ec12f38>

----------------------------------------------------------------------
Ran 3 tests in 0.000s

FAILED (failures=2)

assertEqual 是否用于检查两个实例是否相同？或者我的设置有什么问题吗？为什么 test_name_equal() 失败了？

Answer 1

您的测试工作绝对正常，但发现了一个错误。欢呼!

您的两个 Car 对象可能具有相同的名称，但为什么这意味着它们是同一辆车？您的代码中没有任何内容可以做到这一点。

如果您希望如此，请在 Car 类上实现 __eq__:

def __eq__(self, other):
    """Return True if other is also a car and has the same name as
    this one."""

    return isinstance(other, Car) and self.name == other.name

然后该测试应该通过。