How to speed up pytest

Solution 1:

Using the norecursedirs option in pytest.ini or tox.ini can save a lot of collection time, depending on what other files you have in your working directory. My collection time is roughly halved for a suite of 300 tests when I have that in place (0.34s vs 0.64s).

If you're already using tox like I am, you just need to add the following in your tox.ini:

[pytest]
norecursedirs = docs *.egg-info .git appdir .tox

You can also add it in a free-standing pytest.ini file.

The pytest documentation has more details on pytest configuration files.

Solution 2:

I was having the same problem where I was calling pytest at the root of my project and my tests were three subdirectories down. The collection was taking 6-7 seconds before 0.4 seconds of actual test execution.

My solution initially was to call pytest with the relative path to the tests:

pytest src/www/tests/

If doing that speeds up your collection also, you can add the relative path to the tests to the end of the addopts setting in your pytest.ini - eg:

[pytest]
addopts = --doctest-glob='test_*.md' -x src/www/tests/

This dropped the collection + execution time down to about a second and I could still just call pytest as I was before.

Solution 3:

With xdist you can parallelize pytest runs. It allows even to ship tests to remote machines. Depends on your setup it can speedup quite a bit :)

Solution 4:

For me, adding PYTHONDONTWRITEBYTECODE=1 to my environment variables achieved a massive speedup! Note that I am using network drives which might be a factor.

• Windows Batch: set PYTHONDONTWRITEBYTECODE=1
• Unix: export PYTHONDONTWRITEBYTECODE=1
• subprocess.run: Add keyword env={'PYTHONDONTWRITEBYTECODE': '1'}
• PyCharm already set this variable automatically for me.

Note that the first two options only remain active for your current terminal session.