[#9219] Disable test_plugin.DeveloperSetupTests.test_freshPyReplacesStalePyc under PyPy2

[dansut]

The test_plugin.DeveloperSetupTests.test_freshPyReplacesStalePyc test relies on removing the initial stale.py plugin module to ensure .pyc file is being used during sanity check, this causes the import during twisted.plugin.getCache() to ERROR out under PyPy2.

This PR Disables the test under PyPy2 until a better way can be found to deal with this situation.

[rodrigc]

Does this test pass on Pypy3? Is _PY3 true with Pypy3?

We don't currently have a Pypy3 buildbot to verify this (but we should probably add one).

[dansut]

@rodrigc this test does indeed pass under PyPy3 5.8.0, and yes _PY3 does seem to be true under this environment.

I ran the full Twisted test suite under this environment and was surprised how well it did, many of the FAILs and ERRORs seem to be for the same problem as well (eg. StringIO missing)

[rodrigc]

Cool

[rodrigc]

Just out of curiousity, does coverage work under pypy3?

Something like:

coverage run -p --rcfile=.coveragerc -m twisted.trial --reactor=default --reporter=verbose twisted

[dansut]

It does appear that coverage works under pypy3, the report summary last line is:

TOTAL 147322 36266 26060 2337 72.94%

[rodrigc]

@dansut wow that's good news. Before the coverage command did not seem to work with pypy.

[dansut]

That is good news @rodrigc - I'm now going to check coverage with the pypy2 build of 5.8.0

It probably would be a good idea if I'd given you the trial result summary for pypy3 that matched with that coverage report last line, here it is:

FAILED (skips=3381, failures=69, errors=208, successes=8307)

This doesn't seem like a catastrophic starting point to get this to be a supported platform - but I'm gonna focus on the pypy2 build first 😄

[rodrigc]

Hey @dansut , since you seem to be motivated with Pypy, do you have any cycles to help
with a few more items? If you look at the following test output:

https://buildbot.twistedmatrix.com/builders/ubuntu16.04-pypy5/builds/91/steps/select/logs/stdio

You will see that these tests are failing on Pypy 5.8.0:

twisted.test.test_threadpool.ThreadPoolTests.test_threadCreationArgumentsCallInThreadWithCallback
twisted.test.test_reflect.PrefixedMethodsTests.test_onlyObject
twisted.test.test_reflect.AccumulateMethodsTests.test_ownClass
twisted.test.test_reflect.AccumulateMethodsTests.test_baseClass
twisted.test.test_rebuild.RebuildTests.testFileRebuild
twisted.test.test_plugin.PluginTests.test_detectFilesChanged
twisted.persisted.test.test_styles.UnpickleMethodTests.test_instanceBuildingNamePresent
twisted.persisted.test.test_styles.UnpickleMethodTests.test_instanceBuildingNameNotPresent

If you have the time/interest, could you take a look at these tests and see if
there are any that we could quickly mark as skipped?

[dansut]

@rogric - seen latest buildbot and my intention is to go through each of these in turn and assess. Not sure how much time I'll have over weekend, but Monday I'll be straight back into the attempting to get the PyPy build as clean as I can.