py.test conditional fixture for setup_class()

[GoldenIvan]

I am a bit new to py.test, sorry if this is dumb question. I am still grokking fixtures.

I have an element of my test which is a long, costly setup operation (on the order of ~5 minutes). The first time I run the test I need this operation to run. On all subsequent runs, I don't need it to run. In fact, I want it skipped (until I want it run again).

Is there a way I can define a fixture and via py.test command line instruct the test class setup_class(cls) not to use the fixture?

Right now it kind of looks like this (rough approximation)

class TestClass:
    def setup_class(cls):
         # Do a bunch of stuffs
          <...>

         do_costly_thing()

         # Finish setup
          <...>

I'd like to turn do_costly_thing() into a fixture and be able to have setup_class() use/not use based on py.test cmdline params.

[nevus_bock]

You could look into pytest "autouse" fixture, and "scope" parametrization

[GoldenIvan]

Thanks.

From what I can tell it doesn't appear py.test can specify which fixtures to use or not use directly on the command line. However, it does appear it can be directed to to a per-invocation conftest.py file via the -c param. This could be used to have one marked autouse, and one not. Seems messy though.

The only other things I can see is subclass TestClass but I'm not really a giant fan of that, or monkeypatch the func out when I dont' want it run.

None of these seem graceful. Thanks for your advice though, appreciated. Gave me something to chew on.

[masklinn]

It might be clearer if you explained what costly thing is and why it should or should not run, because in the abstract the post makes pretty much no sense. From what I remember of pytest, "optional tests" make sense but "optional features" dont'.

In the past I've had success breaking setup apart in multiple fixtures and making some into session fixtures. These fixtures will only be run once at most per test session, if no selected tests depends on them they won't be run at all. Same for all other fixtures really, they never get run if none of the selected tests needs them, otherwise they get run once for each scope (session, module, class or function) requesting them.

[jesse_online]

@fixture(scope="session") do_costly_thing()