Merge pull request #4213 from tybug/remove-gc

Remove `gc.collect()` before each test

hypothesis-python/tests/conftest.py

@@ -68,11 +68,6 @@ def warns_or_raises(request):
         return pytest.warns
 
 
-@pytest.fixture(scope="function", autouse=True)
-def _gc_before_each_test():
-    gc.collect()
-
-
 @pytest.fixture(scope="function", autouse=True)
 def _consistently_increment_time(monkeypatch):
     """Rather than rely on real system time we monkey patch time.time so that

hypothesis-python/tests/cover/test_random_module.py

@@ -161,7 +161,17 @@ def test_find_does_not_pollute_state():
     "ignore:It looks like `register_random` was passed an object that could be garbage collected"
 )
 def test_evil_prng_registration_nonsense():
-    gc_collect()
+    # my guess is that other tests may register randoms that are then marked for
+    # deletion (but not actually gc'd yet). Therefore, depending on the order tests
+    # are run, RANDOMS_TO_MANAGE may start with more entries than after a gc. To
+    # force a clean slate for this test, unconditionally gc.
+    gc.collect()
+    # The first test to call deterministic_PRNG registers a new random instance.
+    # If that's this test, it will throw off our n_registered count in the middle.
+    # start with a no-op to ensure this registration has occurred.
+    with deterministic_PRNG(0):
+        pass
+
     n_registered = len(entropy.RANDOMS_TO_MANAGE)
     r1, r2, r3 = random.Random(1), random.Random(2), random.Random(3)
     s2 = r2.getstate()