什么是Python UnitTest中的assertEqual应该做什么？

Question

这个问题不是上述问题的重复,我不是要求一种方法来比较实例,而是要求方法assertEqual,以及它的目的是什么.

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

文件说,

测试第一和第二是相等的.如果值不相等,则测试将失败.

我assertEqual在一个简单的课上运行三个测试,

上课时考试

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

TestCase

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)

被assertEqual用来检查这两个实例中都一样吗？或者我的设置有什么问题？为什么test_name_equal()失败了？

Answer 1

你的测试工作得非常好,而且发现了一个错误.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？代码中没有任何内容可以做到这一点.

如果您希望如此,请__eq__在Car类上实现:

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

那个测试应该通过.