Fixture variants with different parameters currently cannot coexist

[BorjaEst]

Hi there,

I am wondering, in case you have some expensive setups, if it would be possible to avoid repeating the fixture execution.
See this example.

import pytest

@pytest.fixture(scope="session")
def param1(request):
    print("session param1 is {}".format(request.param))

@pytest.fixture(scope="session")
def param2(request):
    print("session param2 is {}".format(request.param))

@pytest.mark.parametrize('param1', [1, 2], indirect=True)
@pytest.mark.parametrize('param2', [1, 2], indirect=True)
def test_example(param1, param2):
    print("Test done\n")

Provides the following output.

$ pytest -s
========================= test session starts =========================
platform linux -- Python 3.8.3, pytest-6.2.1, py-1.10.0, pluggy-0.13.1
rootdir: /home/.../Temp/test
collected 4 items

test_example.py session param1 is 1
session param2 is 1    # <-- FIRST execution of param2 with 1
Test done

.session param2 is 2
Test done

.session param1 is 2
Test done

.session param2 is 1   # <-- SECOND execution of param2 with 1
Test done

.

========================== 4 passed in 0.01s ==========================

As I defined the fixture as "session" I do not expect to have the fixture running a second time with the same parameter.

How do you think it would be the best way to implement this?
Would it be applicable to parallel testing with xdist?

Thanks,
Borja

[RonnyPfannschmidt]

xdist has examples on how to sync fixtures between local processes

as for having multiple versions coexist, a common pattern is to have a manager type fixture that deals teaedown and having utility fixture that use the manager for setup and teardown, so that setup happens as needed and teardown after usage

the utility fixtures would still be recreated multiple times, but the work would cache in the manager fixture

[BorjaEst]

I see, something like this probably?
(It took me some time to undestand the answer, sorry for the delay)

import pytest

@pytest.fixture(scope="session")
def manager(request):
    print("session param1 is {}".format(request.param))

@pytest.fixture(scope="function")
def util(request, manager):
    print("session param2 is {}".format(request.param))

@pytest.mark.parametrize('manager', [1, 2], indirect=True)
@pytest.mark.parametrize('util', [1, 2], indirect=True)
def test_example(util):
    print("Test done\n")

That would print:

$ pytest -s
========================= test session starts =========================
platform linux -- Python 3.8.3, pytest-6.2.1, py-1.10.0, pluggy-0.13.1
rootdir: /home/.../Temp/test
collected 4 items

test_example.py session param1 is 1
session param2 is 1
Test done

.session param2 is 2
Test done

.session param1 is 2
session param2 is 1
Test done

.session param2 is 2
Test done

.

========================== 4 passed in 0.01s ==========================

Not exactly what I was looking for, as it runs more than 4 tests, but I undestand the idea behind.
Thanks!

[RonnyPfannschmidt]

its not clear what you are asking for, can you make up a example output?