setup_class does not work well with @pytest.fixture

[vipkum2]

What I want: I need a session level setup for some data, this data need by the test scripts/tests, Also test scripts has some class level setup.
Issue: I am using below code to achieve the same but "setup_class" in test script, start executing with each test case. I am expecting it to run only once for the class. Without fixture It run once for class.

Workaround: I can use fixture directly in test case like: def test_01(self,abc):, it works. But I want that If I can only use value of "abc" in setup_class, so only one place I need to access the "abc".

#conftest.py file:

@pytest.fixture(scope="session")
def abc():
    print("\n\n ### ABC Session Level Setup ###")
    abc = 6
    #os.environ["a"] = str(data)
    yield abc
    print("\n\n ### ABC Session Level TearDown ###")

#test03.py
import pytest

class Test3:
    @pytest.fixture(autouse=True)
    def setup_class(self,abc):
        self.d = abc
        print("\n Inside Test3 setup_module",)

    def test_01(self,):
        print("test_01",self.d)

    def test_02(self,):
        print("test_02",self.d)

    def test_03(self,):
        print("test_03", self.d)```

#Execution logs:
vipin@nmjwr7pwg0 test % python3 -m pytest -s -vv test3.py -x
========================================================================= test session starts =========================================================================
platform darwin -- Python 3.10.6, pytest-7.2.0, pluggy-1.0.0 -- /opt/homebrew/opt/[email protected]/bin/python3.10
cachedir: .pytest_cache
rootdir: /Users/vipin/my_mac/pyLogger, configfile: pytest.ini
collected 3 items

test3.py::Test3::test_01

ABC Session Level Setup

Inside Test3 setup_module
test_01 6
PASSED
test3.py::Test3::test_02
Inside Test3 setup_module
test_02 6
PASSED
test3.py::Test3::test_03
Inside Test3 setup_module
test_03 6
PASSED

ABC Session Level TearDown

========================================================================== 3 passed in 0.00s ==========================================================================

[The-Compiler]

Set the fixture scope to "class" for that. Though, typically you would use the fixture directly in your test cases instead of storing things in the class instance.

[The-Compiler]

Can you please show a complete runnable example exhibiting the problem? If I use your example and add an abc fixture, it works as expected.

[The-Compiler]

Ah, my bad, this reproduces the issue:

import pytest

@pytest.fixture(scope="class")
def abc():
    pass


class Test3:
    @pytest.fixture(autouse=True, scope="class")
    def a(self,abc):
        self.d = abc
        print("\n Inside Test3 setup_module",)

    def test_01(self,):
        print("test_01",self.d)

    def test_02(self,):
        print("test_02",self.d)

    def test_03(self,):
        print("test_03", self.d)

(but still - you make it much easier for people to help you if you post something they can run without any more modifications needed, see http://www.sscce.org/)

This indeed fails in the way you described, but that actually makes sense now that I think of it: Every test gets a new instance of your Test3 class, so if you only add your attribute once, it follows that it doesn't exist for the other tests.

As said earlier, typically you'd use d (or whatever you'd call it) as a fixture instead of patching things onto the test instance.

[vipkum2]

I did not get the meaning of line "as a fixture instead of patching things onto the test instance".
Do we have any workaround to achieve the same ?

[RonnyPfannschmidt]

for one, assign things to type(self).foo instead of self.foo

i believe we have a number of issues about needing to error on class scope fixtures in classes that take self

[vipkum2]

Thanks @RonnyPfannschmidt and @The-Compiler !
type(self) worked here.

[The-Compiler]

What I meant above, and what seems a way less hack-ish way to do things, is to use the fixture normally as an argument to your tests:

class Test3:
    @pytest.fixture(scope="class")
    def abc(self):
        pass

    def test_01(self, abc):
        print("test_01", abc)

    def test_02(self, abc):
        print("test_02", abc)

    def test_03(self, abc):
        print("test_03", abc)

[vipkum2]

Yes, this is ideal way. In my case, we have already some scripts, so I am just avoiding to change each place. Thanks you !

[The-Compiler]

In that case, you can always have a class-scope fixture providing your value, but a function-scope fixture setting the attribute:

import pytest

@pytest.fixture(scope="class")
def abc():
    pass


class Test3:
    @pytest.fixture(autouse=True)
    def a(self,abc):
        self.d = abc
        print("\n Inside Test3 setup_module",)

    def test_01(self,):
        print("test_01",self.d)

    def test_02(self,):
        print("test_02",self.d)

    def test_03(self,):
        print("test_03", self.d)