python - 在 pytest 中运行单个文件，该文件是 PEP 420 隐式命名空间包中的模块

Question

我有一个使用相对导入的文件dir/subdir/module.py，以便

python3 dir/subdir/module.py

失败并显示

ModuleNotFoundError: No module named '__main__.test_forward'; '__main__' is not a package

但是

python3 -m dir.subdir.module

运行。

毫不奇怪，

python3 -m pytest dir/subdir/module.py
pytest dir/subdir/module.py

也失败了。我可以从 pytest 运行此模块的测试(而不更改它)吗？

当然，我看过How to test single file under pytest和 https://docs.pytest.org/en/latest/usage.html#cmdline ，但未能找到答案。

这是一个最小的复制示例:

文件proj/main.py:

def func():
    return 1

文件proj/tests.py:

from .main import func

def test_func():
    assert func() == 1

if __name__ == "__main__":
    test_func()

请注意，我按照 PEP 420 在 proj 中省略了 __init__.py .

(venv) romanov@k9-09:~/temp$ python3 -m proj.tests
(venv) romanov@k9-09:~/temp$

测试运行并通过(如果我将 test_func 更改为失败，我会得到预期的结果)。

(venv) romanov@k9-09:~/temp$ python3 proj/tests.py
Traceback (most recent call last):
  File "proj/tests.py", line 1, in <module>
    from .main import func
SystemError: Parent module '' not loaded, cannot perform relative import

使用 pytest:

(venv) romanov@k9-09:~/temp$ pytest proj/tests.py
============================================================================================ test session starts =============================================================================================
platform linux -- Python 3.5.2, pytest-4.3.1, py-1.8.0, pluggy-0.9.0
hypothesis profile 'default' -> database=DirectoryBasedExampleDatabase('/home/romanov/temp/.hypothesis/examples')
rootdir: /home/romanov/temp, inifile:
plugins: hypothesis-4.0.1
collected 0 items / 1 errors

=================================================================================================== ERRORS ===================================================================================================
_______________________________________________________________________________________ ERROR collecting proj/tests.py _______________________________________________________________________________________
proj/tests.py:1: in <module>
    from .main import func
E   SystemError: Parent module '' not loaded, cannot perform relative import
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 errors during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
========================================================================================== 1 error in 0.09 seconds ===========================================================================================

不幸的是，这并不能完全重现问题；这里 ivan_pozdeev 的答案中建议的 pytest --pyargs proj.tests 说 ERROR: file or package not find: proj.tests (missing __init__.py?) 并添加空 >proj/__init__.py 让它运行。

Answer 1

根据Usage and Invocations — pytest documentation :

Run tests from packages

pytest --pyargs pkg.testing

This will import pkg.testing and use its filesystem location to find and run tests from.

In [9]: !ls -R t
t:
__init__.py  main.py  tests.py

In [10]: pwd
Out[10]: u'c:\\Users\\Sasha\\Desktop'

In [7]: os.environ['PYTHONPATH']=r'c:\Users\Sasha\Desktop'

In [8]: !pytest --pyargs t.tests
============================= test session starts =============================
platform win32 -- Python 2.7.15+, pytest-3.0.3, py-1.5.4, pluggy-0.4.0
rootdir: c:\Users\Sasha\Desktop, inifile:
plugins: xdist-1.15.0, mock-1.5.0, instafail-0.3.0
collected 1 items

t\tests.py .

========================== 1 passed in 0.02 seconds ===========================

如果按照 PEP 420 省略 __init__.py，pytest 会变得困惑，因为其逻辑的核心前提是在子树中搜索测试文件并导入它们。如果没有 __init__.py，它就无法确定是否应该将文件作为子包或独立模块导入。