验证pytest中SystemExit的错误代码或消息

时间:2015-05-15 09:46:57

标签: python pytest

根据pytest文档,我可以声明SystemExit()发生,但我想做更多:我还想验证退出代码和任何消息。我尝试了下面的代码,但没有打印,我不确定我需要断言以证明我得到了正确的错误代码。

    with pytest.raises(SystemExit):
        docopt_args = validate_args(docopt_args)
        out, err = pytest.capsys.readouterr()
        assert out == 'Foo'
        print out, err

当我运行我的测试时,它会通过,但就是这样。什么都没打印,我没有得到断言错误。

我希望执行的代码是:

        print '\n' + docopt_args['-d'] + ' is not a valid date\n'
        sys.exit(-3)

2 个答案:

答案 0 :(得分:12)

这适用于最新的pytest

您需要做的只是使用pytest选项运行--capture=sys并依赖于raises()上下文之外的断言(此位因某些原因很重要!

示例:

#!/usr/bin/env python

from __future__ import print_function

import pytest


def f(code=0):
    print("Foo")
    raise SystemExit(code)


def test_f(capsys):
    with pytest.raises(SystemExit):
        f()
    out, err = capsys.readouterr()
    assert out == "Foo\n"
    print(out, err)

<强>演示:

$ py.test -v --capture=sys test_foo.py 
======================================= test session starts ========================================
platform linux2 -- Python 2.7.9 -- py-1.4.27 -- pytest-2.7.0 -- /home/prologic/.virtualenvs/test/bin/python
rootdir: /home/prologic/tmp, inifile: 
collected 1 items 

test_foo.py::test_f PASSED

===================================== 1 passed in 0.00 seconds =====================================

print("Foo")更改为print("Bar")会导致:

$ py.test -v --capture=sys test_foo.py 
======================================= test session starts ========================================
platform linux2 -- Python 2.7.9 -- py-1.4.27 -- pytest-2.7.0 -- /home/prologic/.virtualenvs/test/bin/python
rootdir: /home/prologic/tmp, inifile: 
collected 1 items 

test_foo.py::test_f FAILED

============================================= FAILURES =============================================
______________________________________________ test_f ______________________________________________

capsys = <_pytest.capture.CaptureFixture instance at 0x7f2729405518>

    def test_f(capsys):
        with pytest.raises(SystemExit):
            f()
        out, err = capsys.readouterr()
>       assert out == "Foo\n"
E       assert 'Bar\n' == 'Foo\n'
E         - Bar
E         + Foo

test_foo.py:17: AssertionError
===================================== 1 failed in 0.01 seconds =====================================

我认为这正是你所追求的!

我是用干净的virtualenv

完成的
mkvirtualenv test
pip install pytest

这里的诀窍是阅读并理解Setting capturing methods or disabling capturing

答案 1 :(得分:0)

import pytest

def test_exit():
    with pytest.raises(SystemExit):
        script_exit()