How to change the fixture used in case functions.

[AlbertoRFer]

I have several cases in a class, all of them have a fixture in common, lets call it fixture1 something like.

@pytest.fixture
def fixture1():
    return "dummy-fixture1"

class CaseFixture:
    def case_1(self, fixture1):
        return f"{fixture1}-case-1"

    def case_2(self, fixture1):
        return f"{fixture1}-case-2"

@parametrize_with_cases("case", cases=CaseFixture)
def test_fixture1(case):
    assert case in ["dummy-fixture1-case-1", "dummy-fixture1-case-2"]

Now for my next test function i could reuse the same cases in CaseFixture if the case functions took a different fixture than fixture1, for example fixture2. The naive way with a lot of code duplication would be:

@pytest.fixture
def fixture1():
    return "dummy-fixture1"

class CaseFixture1:
    def case_1(self, fixture1):
        return f"{fixture1}-case-1"

    def case_2(self, fixture1):
        return f"{fixture1}-case-2"

@pytest.fixture
def fixture2():
    return "dummy-fixture2"

class CaseFixture2:
    def case_1(self, fixture2):
        return f"{fixture2}-case-1"

    def case_2(self, fixture2):
        return f"{fixture2}-case-2"

@parametrize_with_cases("case", cases=CaseFixture1)
def test_fixture1(case):
    assert case in ["dummy-fixture1-case-1", "dummy-fixture1-case-2"]

@parametrize_with_cases("case", cases=CaseFixture2)
def test_fixture2(case):
    assert case in ["dummy-fixture2-case-1", "dummy-fixture2-case-2"]

Is there a way of reuse the cases instead? Something like passing the fixture to use from the test function to the Case class methods?

[smarie]

Hi @AlbertoRFer , thanks for your interesting question !

It seems that you would like to de-couple the cases from the parameter of the cases.

My naive proposal would be to consider having cases that return callables, and have the "mix" of fixture + case done by the test itself

@parametrize_with_cases("case", cases=CaseFixture1)
def test_fixture1(case, fixture1):
    actual_case = case(fixture1)
    ...

@parametrize_with_cases("case", cases=CaseFixture2)
def test_fixture2(case, fixture2):
    actual_case = case(fixture2)
    ...

This can be very readable if you choose variable names that are intuitive. For example "data_creator", or "challenger", or "algorithm", or "function" instead of "case".

Note that you can do this in the test function or in another case as there is no limit in nesting.