Merge pull request #7542 from drew2a/fix/call_gc

Add `ensure_gc` for each test call

src/tribler/core/conftest.py

@@ -1,4 +1,5 @@
 import asyncio
+import gc
 import logging
 import platform
 import sys
@@ -64,6 +65,29 @@ def pytest_runtest_protocol(item: Function, log=True, nextitem=None):
         yield
 
 
+
+@pytest.fixture(autouse=True)
+def ensure_gc():
+    """ Ensure that the garbage collector runs after each test.
+    This is critical for test stability as we use Libtorrent and need to ensure all its destructors are called. """
+    # For this fixture, it is necessary for it to be called as late as possible within the current test's scope.
+    # Therefore it should be placed at the first place in the "function" scope.
+    # If there are two or more autouse fixtures within this scope, the order should be explicitly set through using
+    # this fixture as a dependency.
+    # See the discussion in https://github.com/Tribler/tribler/pull/7542 for more information.
+
+    yield
+    # Without "yield" the fixture triggers the garbage collection at the beginning of the (next) test.
+    # For that reason, the errors triggered during the garbage collection phase will take place not in the erroneous
+    # test but in the randomly scheduled next test. Usually, these errors are silently suppressed, as any exception in
+    # __del__ methods is silently suppressed, but they still can somehow affect the test.
+    #
+    # By adding the yield we move the garbage collection phase to the end of the current test, to not affect the next
+    # test.
+
+    gc.collect()
+
+
 @pytest.fixture
 def free_port():
     return default_network_utils.get_random_free_port(start=1024, stop=50000)

src/tribler/gui/tests/conftest.py

@@ -1,3 +1,4 @@
+import gc
 import logging
 import time
 
@@ -61,3 +62,25 @@ def pytest_runtest_protocol(item, log=True, nextitem=None):
     total = time.time() - pytest_start_time
     if enable_extended_logging:
         print(f' in {duration:.3f}s ({total:.1f}s in total)', end='')
+
+
+@pytest.fixture(autouse=True)
+def ensure_gc():
+    """ Ensure that the garbage collector runs after each test.
+    This is critical for test stability as we use Libtorrent and need to ensure all its destructors are called. """
+    # For this fixture, it is necessary for it to be called as late as possible within the current test's scope.
+    # Therefore it should be placed at the first place in the "function" scope.
+    # If there are two or more autouse fixtures within this scope, the order should be explicitly set through using
+    # this fixture as a dependency.
+    # See the discussion in https://github.com/Tribler/tribler/pull/7542 for more information.
+
+    yield
+    # Without "yield" the fixture triggers the garbage collection at the beginning of the (next) test.
+    # For that reason, the errors triggered during the garbage collection phase will take place not in the erroneous
+    # test but in the randomly scheduled next test. Usually, these errors are silently suppressed, as any exception in
+    # __del__ methods is silently suppressed, but they still can somehow affect the test.
+    #
+    # By adding the yield we move the garbage collection phase to the end of the current test, to not affect the next
+    # test.
+
+    gc.collect()