Test collection is ~50x slower when project root dir is specified

[yozlet]

Compare: both of these commands are run in my project root dir, differ only by whether the path to that root dir is explicit or implicit, yet the second one takes 50x longer.

$ python -m pytest --collect-only                                                           at 2019-03-01 13:54:32
=============================================== test session starts ===============================================
platform darwin -- Python 3.6.8, pytest-4.3.0, py-1.8.0, pluggy-0.9.0
Django settings: $PROJECT_NAME.settings.pytest (from ini file)
rootdir: /Users/yoz/$PROJECT_NAME, inifile: pytest.ini
plugins: mock-1.10.1, metadata-1.8.0, jest-0.3.0, django-3.4.8, cov-2.6.1
collected 333 items

[ output skipped ]

========================================== no tests ran in 1.87 seconds ===========================================

$ python -m pytest --collect-only .                                                     at 2019-03-01 13:52:56
=============================================== test session starts ===============================================
platform darwin -- Python 3.6.8, pytest-4.3.0, py-1.8.0, pluggy-0.9.0
Django settings: $PROJECT_NAME.settings.pytest (from ini file)
rootdir: /Users/yoz/$PROJECT_NAME, inifile: pytest.ini
plugins: mock-1.10.1, metadata-1.8.0, jest-0.3.0, django-3.4.8, cov-2.6.1
collected 333 items

[ output skipped ]

========================================== no tests ran in 83.55 seconds ==========================================

I've done this multiple times, so I'm fairly sure it's not a cache issue.

If it's any help: this is running in a pipenv-run virtualenv inside a conda environment (yes, this is suboptimal).

[yozlet]

I think this has something to do with not properly using pytest.ini, even though it lists the file in output. When I comment out the testpaths setting that lists the subdirs containing tests, both commands take roughly the same time and the Package tags in the output are alphabetically ordered, rather than following the order in the testpaths configuration.

Note, however, that pytest --trace-config produces identical output (other than memory locations) for both, which isn't helpful.

[nicoddemus]

Hi @yozlet,

This is actually the expected behavior, the docs for testpaths say:

Sets list of directories that should be searched for tests when no specific directories, files or test ids are given in the command line

So by passing ., you are skipping testpaths, which is intentional. 👍

[blueyed]

Yeah, apparently not really an issue.

But maybe we could include testpaths in the header, next to rootdir/inifile?

That would at least show a diff in the outputs above.

[nicoddemus]

Sure, created a new issue for it.

@yozlet I'm closing this for now, but feel free to followup with further questions.