Flaky test: test_request_garbage

[blueyed]

It was marked to be skipped with xdist in 4808145 (#4144 (comment)). The failure mentioned there (#4144 (comment)) appears to be different from the one below though.

assert leaked_types == 0

https://travis-ci.org/pytest-dev/pytest/jobs/451681349#L997

=================================== FAILURES ===================================
____________________ TestRequestBasic.test_request_garbage _____________________
self = <fixture.TestRequestBasic object at 0x7f2f9b626080>
testdir = <Testdir local('/tmp/pytest-of-travis/pytest-0/test_request_garbage0')>
    @pytest.mark.skipif(
        hasattr(sys, "pypy_version_info"),
        reason="this method of test doesn't work on pypy",
    )
    def test_request_garbage(self, testdir):
        try:
            import xdist  # noqa
        except ImportError:
            pass
        else:
            pytest.xfail("this test is flaky when executed with xdist")
        testdir.makepyfile(
            """
            import sys
            import pytest
            from _pytest.fixtures import PseudoFixtureDef
            import gc
    
            @pytest.fixture(autouse=True)
            def something(request):
                original = gc.get_debug()
                gc.set_debug(gc.DEBUG_SAVEALL)
                gc.collect()
    
                yield
    
                try:
                    gc.collect()
                    leaked_types = sum(1 for _ in gc.garbage
                                       if isinstance(_, PseudoFixtureDef))
    
                    # debug leaked types if the test fails
                    print(leaked_types)
    
                    gc.garbage[:] = []
    
                    assert leaked_types == 0
                finally:
                    gc.set_debug(original)
    
            def test_func():
                pass
        """
        )
        result = testdir.runpytest()
>       result.stdout.fnmatch_lines("* 1 passed in *")
E       Failed: nomatch: '* 1 passed in *'
E           and: '============================= test session starts =============================='
E           and: 'platform linux -- Python 3.7.1, pytest-3.10.1.dev17+g176d274, py-1.7.0, pluggy-0.8.0'
E           and: "hypothesis profile 'default' -> database=DirectoryBasedExampleDatabase('/home/travis/build/pytest-dev/pytest/.hypothesis/examples')"
E           and: 'rootdir: /tmp/pytest-of-travis/pytest-0/test_request_garbage0, inifile:'
E           and: 'plugins: hypothesis-3.82.1'
E           and: 'collected 1 item'
E           and: ''
E           and: 'test_request_garbage.py .E                                               [100%]'
E           and: ''
E           and: '==================================== ERRORS ===================================='
E           and: '________________________ ERROR at teardown of test_func ________________________'
E           and: ''
E           and: "request = <SubRequest 'something' for <Function 'test_func'>>"
E           and: ''
E           and: '    @pytest.fixture(autouse=True)'
E           and: '    def something(request):'
E           and: '        original = gc.get_debug()'
E           and: '        gc.set_debug(gc.DEBUG_SAVEALL)'
E           and: '        gc.collect()'
E           and: '    '
E           and: '        yield'
E           and: '    '
E           and: '        try:'
E           and: '            gc.collect()'
E           and: '            leaked_types = sum(1 for _ in gc.garbage'
E           and: '                               if isinstance(_, PseudoFixtureDef))'
E           and: '    '
E           and: '            # debug leaked types if the test fails'
E           and: '            print(leaked_types)'
E           and: '    '
E           and: '            gc.garbage[:] = []'
E           and: '    '
E           and: '>           assert leaked_types == 0'
E           and: 'E           assert 4 == 0'
E           and: ''
E           and: 'test_request_garbage.py:24: AssertionError'
E           and: '--------------------------- Captured stdout teardown ---------------------------'
E           and: '4'
E           and: '====================== 1 passed, 1 error in 0.62 seconds ======================='
E           and: ''
E       remains unmatched: '* 1 passed in *'
/home/travis/build/pytest-dev/pytest/testing/python/fixture.py:545: Failed
----------------------------- Captured stdout call -----------------------------
============================= test session starts ==============================
platform linux -- Python 3.7.1, pytest-3.10.1.dev17+g176d274, py-1.7.0, pluggy-0.8.0
hypothesis profile 'default' -> database=DirectoryBasedExampleDatabase('/home/travis/build/pytest-dev/pytest/.hypothesis/examples')
rootdir: /tmp/pytest-of-travis/pytest-0/test_request_garbage0, inifile:
plugins: hypothesis-3.82.1
collected 1 item
test_request_garbage.py .E                                               [100%]
==================================== ERRORS ====================================
________________________ ERROR at teardown of test_func ________________________
request = <SubRequest 'something' for <Function 'test_func'>>
    @pytest.fixture(autouse=True)
    def something(request):
        original = gc.get_debug()
        gc.set_debug(gc.DEBUG_SAVEALL)
        gc.collect()
    
        yield
    
        try:
            gc.collect()
            leaked_types = sum(1 for _ in gc.garbage
                               if isinstance(_, PseudoFixtureDef))
    
            # debug leaked types if the test fails
            print(leaked_types)
    
            gc.garbage[:] = []
    
>           assert leaked_types == 0
E           assert 4 == 0
test_request_garbage.py:24: AssertionError
--------------------------- Captured stdout teardown ---------------------------
4
====================== 1 passed, 1 error in 0.62 seconds =======================
=========================== short test summary info ============================
FAIL testing/python/fixture.py::TestRequestBasic::()::test_request_garbage

[blueyed]

Hopefully resolved through #4457 - otherwise let's reopen this.