Add a test to expose leaked PseudoFixtureDef types.

testing/python/fixture.py

@@ -519,6 +519,41 @@ class TestRequestBasic(object):
         assert len(arg2fixturedefs) == 1
         assert arg2fixturedefs['something'][0].argname == "something"
 
+    def test_request_garbage(self, testdir):
+        testdir.makepyfile("""
+            import sys
+            import pytest
+            import gc
+
+            @pytest.fixture(autouse=True)
+            def something(request):
+                # this method of test doesn't work on pypy
+                if hasattr(sys, "pypy_version_info"):
+                    yield
+                else:
+                    original = gc.get_debug()
+                    gc.set_debug(gc.DEBUG_SAVEALL)
+                    gc.collect()
+
+                    yield
+
+                    gc.collect()
+                    leaked_types = sum(1 for _ in gc.garbage
+                                    if 'PseudoFixtureDef' in str(_))
+
+                    gc.garbage[:] = []
+
+                    try:
+                        assert leaked_types == 0
+                    finally:
+                        gc.set_debug(original)
+
+            def test_func():
+                pass
+        """)
+        reprec = testdir.inline_run()
+        reprec.assertoutcome(passed=1)
+
     def test_getfixturevalue_recursive(self, testdir):
         testdir.makeconftest("""
             import pytest