Possible to expand the fixture return value in parametrize?

[schtibe]

I would like to parametrize a test with the return value of a fixture.

Example:

@pytest.fixture
def links(browser): // assume broser was a fixture
    return browser.find_by_tag('a')

@pytest.mark.parametrize("link", links) // here expand the links fixture return value
def test_func(link):
     // test that link here

Is this possible with pytest-lazy-fixture? (or maybe even pytest itself?) Or might it be a nice feature?

[TvoroG]

Hi! Yes, you can do it with pytest-lazy-fixture:

@pytest.fixture
def links(browser): # assume browser was a fixture
    return browser.find_by_tag('a')

@pytest.mark.parametrize("link", [
    pytest.lazy_fixture('links')
]) # here expand the links fixture return value
def test_func(link):
     # test that link here

[schtibe]

This way i get following error:

   return [LazyFixture(name) for name in names]
E   TypeError: 'function' object is not iterable

[TvoroG]

There was a similar issue: #6. For now It's not possible to implement this feature.

[TvoroG]

If you have some other issues or questions feel free to reopen it or create another one

[tovmeod]

I'm interested in something like that. Did the situation change? is it possible to implement this today? if not, why not?

[TvoroG]

Check out pytest-dev/pytest#4050. I think the main reason here is that you want to generate test cases during runtime, and pytest can do it only during the collection stage. Although I'm not sure.

[jxramos]

It is looking like this collection stage constraint is indeed what may be lurking here...

per design all parametization happens at collection time
StackOverflow Answer: pytest test needs parametrization at collection phase and at setup time