unit tests are slow

[azmeuk]

Testing the whole test suite takes 59s for the 118 tests on my computer (which is very capable).

With pytest-xdist and 8 CPUs this goes down to 17s (pytest -n auto)

pytest --durations 10 gives us those stats:

2.08s call     ihatemoney/tests/api_test.py::TestAPI::test_project
1.99s call     ihatemoney/tests/api_test.py::TestAPI::test_bills_with_calculation
1.97s call     ihatemoney/tests/history_test.py::TestHistory::test_clear_ip_records
1.88s call     ihatemoney/tests/api_test.py::TestAPI::test_member
1.77s call     ihatemoney/tests/api_test.py::TestAPI::test_bills
1.62s call     ihatemoney/tests/api_test.py::TestAPI::test_currencies
1.31s call     ihatemoney/tests/budget_test.py::TestBudget::test_edit_project
1.08s call     ihatemoney/tests/history_test.py::TestHistory::test_disable_clear_no_new_records
1.02s call     ihatemoney/tests/history_test.py::TestHistory::test_project_privacy_edit2
1.00s call     ihatemoney/tests/history_test.py::TestHistory::test_project_privacy_edit

Looking a bit more closely with pytest-profiling and snakeviz, I can see that the longest function call is werkzeug.security.check_password_hash from the need_auth decorator:

ihatemoney/ihatemoney/api/common.py

Line 28 in 0187932

if project and check_password_hash(project.password, auth.password):

It seems to be a known issue, and one way to mitigate this is to generate lower security password hashes.

By using method='pbkdf2:sha1:1000' in generate_password_hash tests run in 24s (instead of 59s) or 8s with xdist (instead of 17s).

I suggest to use a faster and less secure hash algorithm to run unit tests, but still use the default algorithm in other environment. I think a simple solution would be to add two configuration parameters PASSWORD_HASH_METHOD and PASSWORD_HASH_SALT that would be passed as arguments in generate_password_hash. By default those vars would be unset, except in the unit test environment where they would have convenient values.

I would volunteer to provide a PR for this.

What do you think?

[zorun]

Good catch, looks good to me, go for it!

[almet]

Thanks for the detailed explanation. It's very useful to learn about pytest-xdist and pytest-profiling :-)