Pytest: Deprecate "pytest_funcarg__" prefix for fixtures

[nicoddemus]

Start to issue deprecation warnings when fixtures are declared using this legacy idiom, to be removed at some point later in time.

[nicoddemus]

cc @obestwalter

[nicoddemus]

Not sure if it's worth, as keeping support for this old form is simple enough too

[RonnyPfannschmidt]

i want to see this removed :) it complicates things as its not sanely layered

[obestwalter]

It's not explicitly deprecated yet. Shall we add a deprecation warning before 3.0? I just grepped through the code and there are loads of tests using it. Updating those tests to use the fixture decorator would be a nice low hanging fruit task.

[nicoddemus]

OK, I think we should introduce a deprecation warning for 3.0 then. Added it to the Wiki.

[RonnyPfannschmidt]

done in #1714

[jsn1993]

For pytest_funcargs__, what is the alternative approach? Since some legacy code have this and I'm new to py.test.

[nicoddemus]

Just replace this:

def pytest_funcargs__hello():
    ...

with:

@pytest.fixture
def hello():
    ...

:wink:

[nickdirienzo]

@nicoddemus after updating to 3.0.1, I started seeing the warning even though I don't use pytest_funcarg__ anywhere in my code (I only use new-style fixture decorators). Happy to share more info if needed—and tbh, I haven't dug into why this is popping up for my fixtures.

Edit: well, this is embarrassing. It says it in the warning. My warning was due to pytest_cov. Sorry, folks, for the misinformation.

[The-Compiler]

@nickdirienzo Can you show the full, exact warning you get?

[nickdirienzo]

@The-Compiler sure:

WC1 None pytest_funcarg__cov: declaring fixtures using "pytest_funcarg__" prefix is deprecated and scheduled to be removed in pytest 4.0.  Please remove the prefix and use the @pytest.fixture decorator instead.

After quickly grepping for pytest_funcarg__cov, I learned that it's a fixture in pytest_cov's tests. Whoops. I wonder if it'd be helpful to provide the fully qualified name for the location of the fixture in question?

[The-Compiler]

That might be useful indeed - and you should upgrade to pytest-cov 2.3.1 :wink:

[nickdirienzo]

Heh, thanks. 😄

[standage]

I got this message with pytest_cov installed, even though my project wasn't using it. Upgrading pytest_cov made it go away.