无法在装饰器中捕获 pytest 的结果

我的 pytest 测试装饰器在调用函数后立即退出装饰器。如果我使用 python 而不是 pytest 运行该文件，效果会很好。

这是代码：

def dec(func):
    def wrapper(*args, **kwargs):
        print('do some stuff')
        result = func(*args, **kwargs)
        print('ran function')
        return False if result else return True
    return wrapper

@dec
def test_something_is_not_true():
    return False # assert False

@dec
def test_something_is_true():
    return True # assert True


print(test_something_is_not_true())
print(test_something_is_true())

当我用 python 运行该文件时，结果如下：

C:\tests> python test.py
do some stuff
ran function
True
do some stuff
ran function
False

效果很好！

但是当我用 pytest 运行它时，它停在result = func(*args, **kwargs)行并且从不执​​行print('ran function') line:

C:\tests>pytest test.py
============================= test session starts =============================
platform win32 -- Python 3.6.4, pytest-3.3.2, py-1.5.2, pluggy-0.6.0
rootdir: C:\, inifile:
plugins: metadata-1.7.0, jira-0.3.6, html-1.19.0
collected 2 items

test.py F.                                                               [100%]

================================== FAILURES ===================================
_________________________ test_something_is_not_true __________________________

args = (), kwargs = {}

    def wrapper(*args, **kwargs):
        print('do some stuff')
>       result = func(*args, **kwargs)

test.py:20:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

    @dec
    def test_something_is_not_true():
>       assert False
E       assert False

test.py:31: AssertionError
---------------------------- Captured stdout call -----------------------------
do some stuff
===================== 1 failed, 1 passed in 0.11 seconds ======================

正如您所看到的，装饰器函数实际上并没有做任何事情...但是如果我能让它工作，那么我可以查看测试是否通过了该函数，如果是，则根据通过的结果执行一些额外的逻辑或测试失败。也许使用装饰器来完成捕获测试的输出并不是最好的方法？

你会怎么办？

如果您需要在测试之前和之后执行代码，可以在fixture https://docs.pytest.org/en/latest/fixture.html。例子：

import pytest

@pytest.fixture
def wrapper(request):
    print('\nhere I am before the test')
    print('test function name is', request.node.name)
    print('test file is located under', request.node.fspath)
    yield
    print('\nand here I am after the test')


@pytest.mark.usefixtures('wrapper')
def test_spam_good():
    assert True

@pytest.mark.usefixtures('wrapper')
def test_spam_bad():
    assert False

正如您所看到的，这比编写自定义装饰器要强大得多。作为pytest非常擅长围绕测试进行元编程，您可能需要的很多东西已经存在，您只需要知道如何访问它即可。pytest docs https://docs.pytest.org/en/latest/reference.html包含许多适合初学者的示例和食谱。

如果您需要夹具中的测试结果，文档中有一个方法：在夹具中提供测试结果信息 https://docs.pytest.org/en/latest/example/simple.html#making-test-result-information-available-in-fixtures。创建文件conftest.py在项目根目录中包含以下内容：

import pytest


@pytest.hookimpl(tryfirst=True, hookwrapper=True)
def pytest_runtest_makereport(item, call):
    # execute all other hooks to obtain the report object
    outcome = yield
    rep = outcome.get_result()

    # set a report attribute for each phase of a call, which can
    # be "setup", "call", "teardown"

    setattr(item, "rep_" + rep.when, rep)

现在您可以通过以下方式访问测试结果request自定义装置中的装置：

@pytest.fixture
def something(request):
    yield
    # request.node is an "item" because we use the default
    # "function" scope
    if request.node.rep_setup.failed:
        print("setting up a test failed!", request.node.nodeid)
    elif request.node.rep_setup.passed:
        if request.node.rep_call.failed:
            print("executing test failed", request.node.nodeid)