and also fixes a regression in pytest 8.0.0 where `setup_method` crashes
if the class has static or class method tests.
It is allowed to have a test class with static/class methods which
request non-static/class method fixtures (including `setup_method`
xunit-fixture). I take it as a given that we need to support this
somewhat odd scenario (stdlib unittest also supports it).
This raises a question -- when a staticmethod test requests a bound
fixture, what is that fixture's `self`?
stdlib unittest says - a fresh instance for the test.
Previously, pytest said - some instance that is shared by all
static/class methods. This is definitely broken since it breaks test
isolation.
Change pytest to behave like stdlib unittest here.
In practice, this means stopping to rely on `self.obj.__self__` to get
to the instance from the test function's binding. This doesn't work
because staticmethods are not bound to anything.
Instead, keep the instance explicitly and use that.
BTW, I think this will allow us to change `Class`'s fixture collection
(`parsefactories`) to happen on the class itself instead of a class
instance, allowing us to avoid one class instantiation. But needs more
work.
Fixes#12065.
0dc0360351