Parametrize global variables best practice

[TerranWorks]

Hello, I'm using pytest to test my sqlalchemy backend and I found that for most of my tests, i need to see how my code behaves when a speficied user exists and when it doesn't.
I keep having to write this check manually at the beginning of each test but it occured to me that if I could create two users at the beginning of the testing session, only actually create one of them, and then pass both to my tests through the parametrize decorator then i could conveniently check both cases.
But here are the problems:

• I need the users to be created at the beginning and cleaned up at the end which I would like to do with a fixture with session scope but I couldn't get to work
• I need the users to be created only after I've tested the user creation method. I was using the depends plugin for this and I think that part was working

This was so close to being what I wanted but I kept getting TypeError: object of type 'LazyFixture' has no len(). My fixture returns a tuple by the way.

I know this is a little obscure but I have to imagine I'm not the first person to want to do something like this. Does anyone have any suggestions?

[RonnyPfannschmidt]

Without an more detailed example we can't give any suggestion

Please show a example piece of code that demonstrates what you want to work so we can suggest a fit solution/workaround

[nicoddemus]

An example like @RonnyPfannschmidt asked would make things more clear, but from what I can gather, I think you can use a parametrized fixture to solve your problem.

[TerranWorks]

So here is what I have so far and what I'm trying to achieve.

I have a two fixtures with session scope. I generate two sets of user data (a tuple of strings: username, email) but only actually create one of the users. Notice that setup_user depends on test_create_account, since that function should probably be tested before it is used within the fixture

@pytest.mark.depends(on="test_create_account")
@pytest.fixture(scope="session")
def setup_user(connection):
    user=generate_unique_user()
    username,email=user
    proc.create_account(connection, username, email)
    yield user

    #drop user after session 

@pytest.fixture(scope="session")
def setup_fake_user():
    fake_user=generate_unique_user()
    yield fake_user

I then want some way of passing both user and fake_user as parameters to some of my tests so they can be run once with a user that exists and again with a user that doesn't

Criteria:

• Any users that are created should be destroyed by the end. I'd like to create the user at the beginning and keep reusing it but if i have to make a new one for each test that is okay
• Any test or fixture that uses the create_user method should depend on test_create_user
• user and fake_user should be able to be used as parameters for my tests so I can run it once with an existing user and again with a non-existent user which I expect to break everything

Its really a shame that this didnt work because its so close to what I want