[pytest-dev] Access fixtures from unittest.TestCase

[Wolfgang Schnerring]

Hello,

> > Thanks for the hint! Using a method of the TestCase as a wrapper
> > fixture around the actual fixture is clever, but also a little
> > unwieldy... would there be an easy way to introduce an API to make 
> > that easier?
> 
> Thing is that trying to bring pytest fixtures to unittest.TestCase's
> methods directly is very hard, especially given the many
> extensions/subclasses that people use. 

Yeah, I can see how that might be a rather annoying proposition.

On the other hand... I'm not too familiar with the pytest internals (yet? ;),
so this might be totally crazy, but would it be feasible to have an API like
pytest.get_fixture('myfixturename') to retrieve the fixture object? Or is there
no such kind of registry and they are all handled local to the test function?

> do you have to inherit unittest.TestCase, btw? 
> If you don't, all problems go away :)

Yes I do; my use case is migrating projects with large test suites (several
thousand test functions across dozens of packages) from unittest/zope.testrunner
to pytest. Thus, we need mechanisms that work gradually, since anything that
requires us to change something /everywhere/ is a non-starter.

We've already got fancy tooling[1] that converts zope.testrunner-style
"layers"[2] to pytest fixtures, but as you noted above, some test infrastructure
is hidden away in TestCase base classes. So, even if I start a new package
that uses pytest/fixtures from the ground up (as I did last week ;), 
I still need to integrate with some older packages, and their TestCases.

But I guess I can work with the workaround you gave (using a TestCase method as
a fixture to wrap the actual fixture), while refactoring stuff piecemeal
to provide test infrastructure in a testframework-independent way
(you know, being testframework-indepent really isn't a use-case usually...)

Thanks again,
Wolfgang

[1] https://pypi.python.org/pypi/gocept.pytestlayer
[2] https://pypi.python.org/pypi/plone.testing#layers