pytest 如何在第一项断言失败后不退出 for 循环

Posted 2023-02-18

【中文标题】pytest 如何在第一项断言失败后不退出 for 循环

【英文标题】：pytest how not to exit the for loop after first item assert fails

【发布时间】：2022-01-05 23:48:06

【问题描述】：

我是 python 和 pytest 的新手。我正在尝试断言 2 个数据列表。由于列表中的第一个数据不匹配，因此断言在该点失败并且不继续进行下一项。但是我不希望我的执行停止，而是完成循环并捕获整体断言结果。有人可以帮我实现它吗？

代码

def test_compare_database():
        records_src = [(1,James,smith,123),(2,Granpa,smith,124),(3,Linda,smith,123)]
        records_trg = [(1,James,smith,111),(2,Granpa,ron,124),(3,Linda,smith,123)]
        for a, b in zip(records_src, records_trg):
            assert a == b

输出：列表比较中的第一项失败，这是正确的。但它止步于此。我希望整个 for 循环运行并捕获失败的结果。

============================= test session starts =============================
collecting ... collected 1 item

main_test.py::test_compare_database FAILED  
def test_compare_database():
            records_src = [(1,James,smith,123),(2,Granpa,smith,124),(3,Linda,smith,123)]
            records_trg = [(1,James,smith,111),(2,Granpa,ron,124),(3,Linda,smith,123)]
            for a, b in zip(records_src, records_trg):
>               assert a == b
E      AssertionError: assert (1,
 'James',
 'Smith',
 123,)
  != (1,
 'James',
 'Smith',
 111,)

【参考方案1】：

在 python 中使用“try”和“except”关键字允许错误不会干扰程序。这是你要找的吗？如果您想要的话，您还可以将我使用的“out”变量更改为列表变量。我希望这会有所帮助:)

James:int=1
smith:int=2
Granpa:int=3
Linda:int=4
ron:int=5

def test_compare_database()->str:
    out:str=''
    records_src = [(1,James,smith,123),(2,Granpa,smith,124),(3,Linda,smith,123)]
    records_trg = [(1,James,smith,111),(2,Granpa,ron,124),(3,Linda,smith,123)]

    for a, b in zip(records_src,records_trg):
        try:
            assert a==b
            out+="success between "+str(a)+" and "+str(b)+'!'
        except AssertionError as ae:
            out+="there was an assertion error in the program between "+str(a)+" and "+str(b)+'!'
        out+='\n'

    return out

print(test_compare_database())

【参考方案2】：

您可以使用参数化测试根据数据创建多个测试，因此每对元组将在不同的测试中单独断言

def data_source():
    records_src = [(1, 'James', 'smith', 123), (2, 'Granpa', 'smith', 124), (3, 'Linda', 'smith', 123)]
    records_trg = [(1, 'James', 'smith', 111), (2, 'Granpa', 'ron', 124), (3, 'Linda', 'smith', 123)]
    for a, b in zip(records_src, records_trg):
        yield a, b


@pytest.mark.parametrize('a, b', data_source())
def test_compare_database(a, b):
    assert a == b

控制台输出：

main_test.py::test_compare_database[a0-b0] FAILED                     [ 33%]
Tests\main_test.py:33 (test_compare_database[a0-b0])
(1, 'James', 'smith', 123) != (1, 'James', 'smith', 111)

Expected :(1, 'James', 'smith', 111)
Actual   :(1, 'James', 'smith', 123)
<Click to see difference>

a = (1, 'James', 'smith', 123), b = (1, 'James', 'smith', 111)

    @pytest.mark.parametrize('a, b', data_source())
    def test_compare_database(a, b):
>       assert a == b
E       AssertionError: assert (1, 'James', 'smith', 123) == (1, 'James', 'smith', 111)

main_test.py:36: AssertionError
FAILED                     [ 66%]
Tests\main_test.py:33 (test_compare_database[a1-b1])
(2, 'Granpa', 'smith', 124) != (2, 'Granpa', 'ron', 124)

Expected :(2, 'Granpa', 'ron', 124)
Actual   :(2, 'Granpa', 'smith', 124)
<Click to see difference>

a = (2, 'Granpa', 'smith', 124), b = (2, 'Granpa', 'ron', 124)

    @pytest.mark.parametrize('a, b', data_source())
    def test_compare_database(a, b):
>       assert a == b
E       AssertionError: assert (2, 'Granpa', 'smith', 124) == (2, 'Granpa', 'ron', 124)

main_test.py:36: AssertionError
PASSED                     [100%]

【讨论】：

谢谢你是个天才

嗨，这给了我循环中的所有结果。但是我看到了这样的错误“E _pytest.outcomes.XFailed: [NOTRUN] yield tests are removed in pytest 4.0 - test_compare_database will be忽略”

@EverydayLearner 更新你的 pytest 版本。