bpo-25130: Add calls of gc.collect() in tests to support PyPy (GH-28005)

29 files changed, 121 insertions, 11 deletions

diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 4c4da24..7e0b757 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -611,6 +611,7 @@ class _TestProcess(BaseTestCase):
         del c
         p.start()
         p.join()
+        gc.collect()  # For PyPy or other GCs.
         self.assertIs(wr(), None)
         self.assertEqual(q.get(), 5)
         close_queue(q)
@@ -2667,6 +2668,7 @@ class _TestPool(BaseTestCase):
         self.pool.map(identity, objs)
 
         del objs
+        gc.collect()  # For PyPy or other GCs.
         time.sleep(DELTA)  # let threaded cleanup code run
         self.assertEqual(set(wr() for wr in refs), {None})
         # With a process pool, copies of the objects are returned, check
@@ -4198,6 +4200,7 @@ class _TestFinalize(BaseTestCase):
         util._finalizer_registry.clear()
 
     def tearDown(self):
+        gc.collect()  # For PyPy or other GCs.
         self.assertFalse(util._finalizer_registry)
         util._finalizer_registry.update(self.registry_backup)
 
@@ -4209,12 +4212,14 @@ class _TestFinalize(BaseTestCase):
         a = Foo()
         util.Finalize(a, conn.send, args=('a',))
         del a           # triggers callback for a
+        gc.collect()  # For PyPy or other GCs.
 
         b = Foo()
         close_b = util.Finalize(b, conn.send, args=('b',))
         close_b()       # triggers callback for b
         close_b()       # does nothing because callback has already been called
         del b           # does nothing because callback has already been called
+        gc.collect()  # For PyPy or other GCs.
 
         c = Foo()
         util.Finalize(c, conn.send, args=('c',))
diff --git a/Lib/test/lock_tests.py b/Lib/test/lock_tests.py
index d69bcc9..dffb7d4 100644
--- a/Lib/test/lock_tests.py
+++ b/Lib/test/lock_tests.py
@@ -3,6 +3,7 @@ Various tests for synchronization primitives.
 """
 
 import os
+import gc
 import sys
 import time
 from _thread import start_new_thread, TIMEOUT_MAX
@@ -221,6 +222,7 @@ class BaseLockTests(BaseTestCase):
         lock = self.locktype()
         ref = weakref.ref(lock)
         del lock
+        gc.collect()  # For PyPy or other GCs.
         self.assertIsNone(ref())
 
 
diff --git a/Lib/test/test_array.py b/Lib/test/test_array.py
index 18f78d5..6a48c1c 100644..100755
--- a/Lib/test/test_array.py
+++ b/Lib/test/test_array.py
@@ -1097,6 +1097,7 @@ class BaseTest:
         p = weakref.proxy(s)
         self.assertEqual(p.tobytes(), s.tobytes())
         s = None
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertRaises(ReferenceError, len, p)
 
     @unittest.skipUnless(hasattr(sys, 'getrefcount'),
diff --git a/Lib/test/test_asyncgen.py b/Lib/test/test_asyncgen.py
index 77c15c0..a557cb5 100644
--- a/Lib/test/test_asyncgen.py
+++ b/Lib/test/test_asyncgen.py
@@ -3,6 +3,7 @@ import types
 import unittest
 
 from test.support.import_helper import import_module
+from test.support import gc_collect
 asyncio = import_module("asyncio")
 
 
@@ -871,6 +872,7 @@ class AsyncGenAsyncioTest(unittest.TestCase):
             await g.__anext__()
             await g.__anext__()
             del g
+            gc_collect()  # For PyPy or other GCs.
 
             await asyncio.sleep(0.1)
 
diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
index de00373..92b1a43 100644
--- a/Lib/test/test_asyncio/test_tasks.py
+++ b/Lib/test/test_asyncio/test_tasks.py
@@ -2307,6 +2307,7 @@ class BaseTaskTests:
                 self.new_task(self.loop, gen)
             finally:
                 gen.close()
+        gc.collect()  # For PyPy or other GCs.
 
         self.assertTrue(m_log.error.called)
         message = m_log.error.call_args[0][0]
diff --git a/Lib/test/test_code.py b/Lib/test/test_code.py
index 66c84a9..64fd10d 100644
--- a/Lib/test/test_code.py
+++ b/Lib/test/test_code.py
@@ -137,7 +137,8 @@ try:
 except ImportError:
     ctypes = None
 from test.support import (run_doctest, run_unittest, cpython_only,
-                          check_impl_detail, requires_debug_ranges)
+                          check_impl_detail, requires_debug_ranges,
+                          gc_collect)
 from test.support.script_helper import assert_python_ok
 
 
@@ -510,6 +511,7 @@ class CodeWeakRefTest(unittest.TestCase):
         coderef = weakref.ref(f.__code__, callback)
         self.assertTrue(bool(coderef()))
         del f
+        gc_collect()  # For PyPy or other GCs.
         self.assertFalse(bool(coderef()))
         self.assertTrue(self.called)
 
diff --git a/Lib/test/test_concurrent_futures.py b/Lib/test/test_concurrent_futures.py
index 99651f5..eae98d6 100644
--- a/Lib/test/test_concurrent_futures.py
+++ b/Lib/test/test_concurrent_futures.py
@@ -463,6 +463,7 @@ class ThreadPoolShutdownTest(ThreadPoolMixin, ExecutorShutdownTest, BaseTestCase
         executor.map(abs, range(-5, 5))
         threads = executor._threads
         del executor
+        support.gc_collect()  # For PyPy or other GCs.
 
         for t in threads:
             self.assertRegex(t.name, r'^SpecialPool_[0-4]$')
@@ -473,6 +474,7 @@ class ThreadPoolShutdownTest(ThreadPoolMixin, ExecutorShutdownTest, BaseTestCase
         executor.map(abs, range(-5, 5))
         threads = executor._threads
         del executor
+        support.gc_collect()  # For PyPy or other GCs.
 
         for t in threads:
             # Ensure that our default name is reasonably sane and unique when
@@ -535,6 +537,7 @@ class ProcessPoolShutdownTest(ExecutorShutdownTest):
         call_queue = executor._call_queue
         executor_manager_thread = executor._executor_manager_thread
         del executor
+        support.gc_collect()  # For PyPy or other GCs.
 
         # Make sure that all the executor resources were properly cleaned by
         # the shutdown process
@@ -759,6 +762,7 @@ class AsCompletedTests:
                 futures_list.remove(future)
                 wr = weakref.ref(future)
                 del future
+                support.gc_collect()  # For PyPy or other GCs.
                 self.assertIsNone(wr())
 
         futures_list[0].set_result("test")
@@ -766,6 +770,7 @@ class AsCompletedTests:
             futures_list.remove(future)
             wr = weakref.ref(future)
             del future
+            support.gc_collect()  # For PyPy or other GCs.
             self.assertIsNone(wr())
             if futures_list:
                 futures_list[0].set_result("test")
@@ -865,6 +870,7 @@ class ExecutorTest:
         for obj in self.executor.map(make_dummy_object, range(10)):
             wr = weakref.ref(obj)
             del obj
+            support.gc_collect()  # For PyPy or other GCs.
             self.assertIsNone(wr())
 
 
diff --git a/Lib/test/test_copy.py b/Lib/test/test_copy.py
index ba3d233..f1ca8cb 100644
--- a/Lib/test/test_copy.py
+++ b/Lib/test/test_copy.py
@@ -7,6 +7,7 @@ import abc
 from operator import le, lt, ge, gt, eq, ne
 
 import unittest
+from test import support
 
 order_comparisons = le, lt, ge, gt
 equality_comparisons = eq, ne
@@ -805,6 +806,7 @@ class TestCopy(unittest.TestCase):
         self.assertEqual(v[c], d)
         self.assertEqual(len(v), 2)
         del c, d
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(v), 1)
         x, y = C(), C()
         # The underlying containers are decoupled
@@ -834,6 +836,7 @@ class TestCopy(unittest.TestCase):
         self.assertEqual(v[a].i, b.i)
         self.assertEqual(v[c].i, d.i)
         del c
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(v), 1)
 
     def test_deepcopy_weakvaluedict(self):
@@ -857,6 +860,7 @@ class TestCopy(unittest.TestCase):
         self.assertIs(t, d)
         del x, y, z, t
         del d
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(v), 1)
 
     def test_deepcopy_bound_method(self):
diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
index ffe0e20..20cfc88 100644
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -870,6 +870,7 @@ class TestSubclass(unittest.TestCase):
         p = weakref.proxy(d)
         self.assertEqual(str(p), str(d))
         d = None
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertRaises(ReferenceError, str, p)
 
     def test_strange_subclass(self):
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index 52d7756..7d22087 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -2044,6 +2044,7 @@ class TestEnum(unittest.TestCase):
             raise Exception('Exception not raised.')
 
     def test_missing_exceptions_reset(self):
+        import gc
         import weakref
         #
         class TestEnum(enum.Enum):
@@ -2070,8 +2071,9 @@ class TestEnum(unittest.TestCase):
         class_2_ref = weakref.ref(Class2())
         #
         # The exception raised by Enum creates a reference loop and thus
-        # Class2 instances will stick around until the next gargage collection
+        # Class2 instances will stick around until the next garbage collection
         # cycle, unlike Class1.
+        gc.collect()  # For PyPy or other GCs.
         self.assertIs(class_1_ref(), None)
         self.assertIs(class_2_ref(), None)
 
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index ce7b868..6141f2e 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -656,6 +656,7 @@ class ExceptionTests(unittest.TestCase):
         except MyException as e:
             pass
         obj = None
+        gc_collect()  # For PyPy or other GCs.
         obj = wr()
         self.assertIsNone(obj)
 
@@ -667,6 +668,7 @@ class ExceptionTests(unittest.TestCase):
         except MyException:
             pass
         obj = None
+        gc_collect()  # For PyPy or other GCs.
         obj = wr()
         self.assertIsNone(obj)
 
@@ -678,6 +680,7 @@ class ExceptionTests(unittest.TestCase):
         except:
             pass
         obj = None
+        gc_collect()  # For PyPy or other GCs.
         obj = wr()
         self.assertIsNone(obj)
 
@@ -690,6 +693,7 @@ class ExceptionTests(unittest.TestCase):
             except:
                 break
         obj = None
+        gc_collect()  # For PyPy or other GCs.
         obj = wr()
         self.assertIsNone(obj)
 
@@ -708,6 +712,7 @@ class ExceptionTests(unittest.TestCase):
             # must clear the latter manually for our test to succeed.
             e.__context__ = None
             obj = None
+            gc_collect()  # For PyPy or other GCs.
             obj = wr()
             # guarantee no ref cycles on CPython (don't gc_collect)
             if check_impl_detail(cpython=False):
@@ -898,6 +903,7 @@ class ExceptionTests(unittest.TestCase):
         next(g)
         testfunc(g)
         g = obj = None
+        gc_collect()  # For PyPy or other GCs.
         obj = wr()
         self.assertIsNone(obj)
 
@@ -951,6 +957,7 @@ class ExceptionTests(unittest.TestCase):
             raise Exception(MyObject())
         except:
             pass
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(e, (None, None, None))
 
     def test_raise_does_not_create_context_chain_cycle(self):
@@ -1413,6 +1420,7 @@ class ExceptionTests(unittest.TestCase):
             self.assertNotEqual(wr(), None)
         else:
             self.fail("MemoryError not raised")
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(wr(), None)
 
     @no_tracing
@@ -1433,6 +1441,7 @@ class ExceptionTests(unittest.TestCase):
             self.assertNotEqual(wr(), None)
         else:
             self.fail("RecursionError not raised")
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(wr(), None)
 
     def test_errno_ENOTDIR(self):
@@ -1453,6 +1462,7 @@ class ExceptionTests(unittest.TestCase):
         with support.catch_unraisable_exception() as cm:
             del obj
 
+            gc_collect()  # For PyPy or other GCs.
             self.assertEqual(cm.unraisable.object, BrokenDel.__del__)
             self.assertIsNotNone(cm.unraisable.exc_traceback)
 
diff --git a/Lib/test/test_file.py b/Lib/test/test_file.py
index 1ec756f..1146a373 100644
--- a/Lib/test/test_file.py
+++ b/Lib/test/test_file.py
@@ -7,6 +7,7 @@ from weakref import proxy
 import io
 import _pyio as pyio
 
+from test.support import gc_collect
 from test.support.os_helper import TESTFN
 from test.support import os_helper
 from test.support import warnings_helper
@@ -30,6 +31,7 @@ class AutoFileTests:
         self.assertEqual(self.f.tell(), p.tell())
         self.f.close()
         self.f = None
+        gc_collect()  # For PyPy or other GCs.
         self.assertRaises(ReferenceError, getattr, p, 'tell')
 
     def testAttributes(self):
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index ff611a9..cdca5a8 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -9,7 +9,7 @@ from array import array
 from weakref import proxy
 from functools import wraps
 
-from test.support import (run_unittest, cpython_only, swap_attr)
+from test.support import run_unittest, cpython_only, swap_attr, gc_collect
 from test.support.os_helper import (TESTFN, TESTFN_UNICODE, make_bad_fd)
 from test.support.warnings_helper import check_warnings
 from collections import UserList
@@ -36,6 +36,7 @@ class AutoFileTests:
         self.assertEqual(self.f.tell(), p.tell())
         self.f.close()
         self.f = None
+        gc_collect()  # For PyPy or other GCs.
         self.assertRaises(ReferenceError, getattr, p, 'tell')
 
     def testSeekTell(self):
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index fbf5578..fece825 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -167,6 +167,7 @@ class TestPartial:
         p = proxy(f)
         self.assertEqual(f.func, p.func)
         f = None
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertRaises(ReferenceError, getattr, p, 'func')
 
     def test_with_bound_and_unbound_methods(self):
diff --git a/Lib/test/test_generators.py b/Lib/test/test_generators.py
index 53d579e..d14c757 100644
--- a/Lib/test/test_generators.py
+++ b/Lib/test/test_generators.py
@@ -1966,6 +1966,8 @@ True
 """
 
 coroutine_tests = """\
+>>> from test.support import gc_collect
+
 Sending a value into a started generator:
 
 >>> def f():
@@ -2189,7 +2191,7 @@ And finalization:
 
 >>> g = f()
 >>> next(g)
->>> del g
+>>> del g; gc_collect()  # For PyPy or other GCs.
 exiting
 
 
@@ -2204,7 +2206,7 @@ GeneratorExit is not caught by except Exception:
 
 >>> g = f()
 >>> next(g)
->>> del g
+>>> del g; gc_collect()  # For PyPy or other GCs.
 finally
 
 
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 32c29ea..273545a 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -4372,6 +4372,31 @@ class SignalsTest(unittest.TestCase):
         """Check that a partial write, when it gets interrupted, properly
         invokes the signal handler, and bubbles up the exception raised
         in the latter."""
+
+        # XXX This test has three flaws that appear when objects are
+        # XXX not reference counted.
+
+        # - if wio.write() happens to trigger a garbage collection,
+        #   the signal exception may be raised when some __del__
+        #   method is running; it will not reach the assertRaises()
+        #   call.
+
+        # - more subtle, if the wio object is not destroyed at once
+        #   and survives this function, the next opened file is likely
+        #   to have the same fileno (since the file descriptor was
+        #   actively closed).  When wio.__del__ is finally called, it
+        #   will close the other's test file...  To trigger this with
+        #   CPython, try adding "global wio" in this function.
+
+        # - This happens only for streams created by the _pyio module,
+        #   because a wio.close() that fails still consider that the
+        #   file needs to be closed again.  You can try adding an
+        #   "assert wio.closed" at the end of the function.
+
+        # Fortunately, a little gc.collect() seems to be enough to
+        # work around all these issues.
+        support.gc_collect()  # For PyPy or other GCs.
+
         read_results = []
         def _read():
             s = os.read(r, 1)
diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index a99b5e2..4019af0 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -1442,6 +1442,7 @@ class TestBasicOps(unittest.TestCase):
         p = weakref.proxy(a)
         self.assertEqual(getattr(p, '__class__'), type(b))
         del a
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertRaises(ReferenceError, getattr, p, '__class__')
 
         ans = list('abc')
diff --git a/Lib/test/test_queue.py b/Lib/test/test_queue.py
index 508b739..9bb5181 100644
--- a/Lib/test/test_queue.py
+++ b/Lib/test/test_queue.py
@@ -6,6 +6,7 @@ import threading
 import time
 import unittest
 import weakref
+from test.support import gc_collect
 from test.support import import_helper
 from test.support import threading_helper
 
@@ -590,6 +591,7 @@ class BaseSimpleQueueTest:
             q.put(C())
         for i in range(N):
             wr = weakref.ref(q.get())
+            gc_collect()  # For PyPy or other GCs.
             self.assertIsNone(wr())
 
 
diff --git a/Lib/test/test_raise.py b/Lib/test/test_raise.py
index 57da0e1..8dc62a9 100644
--- a/Lib/test/test_raise.py
+++ b/Lib/test/test_raise.py
@@ -438,6 +438,7 @@ class TestContext(unittest.TestCase):
         f()
 
     def test_3611(self):
+        import gc
         # A re-raised exception in a __del__ caused the __context__
         # to be cleared
         class C:
@@ -451,9 +452,11 @@ class TestContext(unittest.TestCase):
             x = C()
             try:
                 try:
-                    x.x
+                    f.x
                 except AttributeError:
+                    # make x.__del__ trigger
                     del x
+                    gc.collect()  # For PyPy or other GCs.
                     raise TypeError
             except Exception as e:
                 self.assertNotEqual(e.__context__, None)
diff --git a/Lib/test/test_scope.py b/Lib/test/test_scope.py
index 29d60ff..6e46dfa 100644
--- a/Lib/test/test_scope.py
+++ b/Lib/test/test_scope.py
@@ -2,6 +2,7 @@ import unittest
 import weakref
 
 from test.support import check_syntax_error, cpython_only
+from test.support import gc_collect
 
 
 class ScopeTests(unittest.TestCase):
@@ -473,6 +474,7 @@ class ScopeTests(unittest.TestCase):
         for i in range(100):
             f1()
 
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(Foo.count, 0)
 
     def testClassAndGlobal(self):
@@ -805,6 +807,7 @@ class ScopeTests(unittest.TestCase):
         tester.dig()
         ref = weakref.ref(tester)
         del tester
+        gc_collect()  # For PyPy or other GCs.
         self.assertIsNone(ref())
 
 
diff --git a/Lib/test/test_set.py b/Lib/test/test_set.py
index b1fab0f..29bb39d 100644
--- a/Lib/test/test_set.py
+++ b/Lib/test/test_set.py
@@ -593,6 +593,7 @@ class TestSet(TestJointOps, unittest.TestCase):
         p = weakref.proxy(s)
         self.assertEqual(str(p), str(s))
         s = None
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertRaises(ReferenceError, str, p)
 
     def test_rich_compare(self):
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index c09f11e..7ac9260 100755
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -870,6 +870,7 @@ class GeneralModuleTests(unittest.TestCase):
             p = proxy(s)
             self.assertEqual(p.fileno(), s.fileno())
         s = None
+        support.gc_collect()  # For PyPy or other GCs.
         try:
             p.fileno()
         except ReferenceError:
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 94a95c7..87967ca 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -3026,6 +3026,7 @@ class POSIXProcessTestCase(BaseTestCase):
         pid = p.pid
         with warnings_helper.check_warnings(('', ResourceWarning)):
             p = None
+            support.gc_collect()  # For PyPy or other GCs.
 
         os.kill(pid, signal.SIGKILL)
         if mswindows:
diff --git a/Lib/test/test_tempfile.py b/Lib/test/test_tempfile.py
index 3a3f6a9..f1d4837 100644
--- a/Lib/test/test_tempfile.py
+++ b/Lib/test/test_tempfile.py
@@ -430,6 +430,7 @@ class TestMkstempInner(TestBadTempdir, BaseTestCase):
             self.do_create(dir=dir).write(b"blat")
             self.do_create(dir=pathlib.Path(dir)).write(b"blat")
         finally:
+            support.gc_collect()  # For PyPy or other GCs.
             os.rmdir(dir)
 
     def test_file_mode(self):
@@ -880,6 +881,8 @@ class TestMktemp(BaseTestCase):
         extant = list(range(TEST_FILES))
         for i in extant:
             extant[i] = self.do_create(pre="aa")
+        del extant
+        support.gc_collect()  # For PyPy or other GCs.
 
 ##     def test_warning(self):
 ##         # mktemp issues a warning when used
diff --git a/Lib/test/test_thread.py b/Lib/test/test_thread.py
index 62b57fa..4ae8a83 100644
--- a/Lib/test/test_thread.py
+++ b/Lib/test/test_thread.py
@@ -132,6 +132,7 @@ class ThreadRunningTests(BasicThreadTest):
             del task
             while not done:
                 time.sleep(POLL_SLEEP)
+                support.gc_collect()  # For PyPy or other GCs.
             self.assertEqual(thread._count(), orig)
 
     def test_unraisable_exception(self):
diff --git a/Lib/test/test_threading_local.py b/Lib/test/test_threading_local.py
index 9862094..13facb5 100644
--- a/Lib/test/test_threading_local.py
+++ b/Lib/test/test_threading_local.py
@@ -37,7 +37,7 @@ class BaseLocalTest:
             t.join()
         del t
 
-        gc.collect()
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(weaklist), n)
 
         # XXX _threading_local keeps the local of the last stopped thread alive.
@@ -46,7 +46,7 @@ class BaseLocalTest:
 
         # Assignment to the same thread local frees it sometimes (!)
         local.someothervar = None
-        gc.collect()
+        support.gc_collect()  # For PyPy or other GCs.
         deadlist = [weak for weak in weaklist if weak() is None]
         self.assertIn(len(deadlist), (n-1, n), (n, len(deadlist)))
 
@@ -89,7 +89,7 @@ class BaseLocalTest:
             # 2) GC the cycle (triggers threadmodule.c::local_clear
             # before local_dealloc)
             del cycle
-            gc.collect()
+            support.gc_collect()  # For PyPy or other GCs.
             e1.set()
             e2.wait()
 
@@ -190,7 +190,7 @@ class BaseLocalTest:
         x.local.x = x
         wr = weakref.ref(x)
         del x
-        gc.collect()
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertIsNone(wr())
 
 
diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py
index 1a5314c..5a3e59c 100644
--- a/Lib/test/test_weakref.py
+++ b/Lib/test/test_weakref.py
@@ -12,6 +12,7 @@ import random
 
 from test import support
 from test.support import script_helper, ALWAYS_EQ
+from test.support import gc_collect
 
 # Used in ReferencesTestCase.test_ref_created_during_del() .
 ref_from_del = None
@@ -135,6 +136,7 @@ class ReferencesTestCase(TestBase):
         ref1 = weakref.ref(o, self.callback)
         ref2 = weakref.ref(o, self.callback)
         del o
+        gc_collect()  # For PyPy or other GCs.
         self.assertIsNone(ref1(), "expected reference to be invalidated")
         self.assertIsNone(ref2(), "expected reference to be invalidated")
         self.assertEqual(self.cbcalled, 2,
@@ -168,13 +170,16 @@ class ReferencesTestCase(TestBase):
         ref1 = weakref.proxy(o, self.callback)
         ref2 = weakref.proxy(o, self.callback)
         del o
+        gc_collect()  # For PyPy or other GCs.
 
         def check(proxy):
             proxy.bar
 
         self.assertRaises(ReferenceError, check, ref1)
         self.assertRaises(ReferenceError, check, ref2)
-        self.assertRaises(ReferenceError, bool, weakref.proxy(C()))
+        ref3 = weakref.proxy(C())
+        gc_collect()  # For PyPy or other GCs.
+        self.assertRaises(ReferenceError, bool, ref3)
         self.assertEqual(self.cbcalled, 2)
 
     def check_basic_ref(self, factory):
@@ -191,6 +196,7 @@ class ReferencesTestCase(TestBase):
         o = factory()
         ref = weakref.ref(o, self.callback)
         del o
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(self.cbcalled, 1,
                      "callback did not properly set 'cbcalled'")
         self.assertIsNone(ref(),
@@ -215,6 +221,7 @@ class ReferencesTestCase(TestBase):
         self.assertEqual(weakref.getweakrefcount(o), 2,
                      "wrong weak ref count for object")
         del proxy
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(weakref.getweakrefcount(o), 1,
                      "wrong weak ref count for object after deleting proxy")
 
@@ -480,6 +487,7 @@ class ReferencesTestCase(TestBase):
                      "got wrong number of weak reference objects")
 
         del ref1, ref2, proxy1, proxy2
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(weakref.getweakrefcount(o), 0,
                      "weak reference objects not unlinked from"
                      " referent when discarded.")
@@ -493,6 +501,7 @@ class ReferencesTestCase(TestBase):
         ref1 = weakref.ref(o, self.callback)
         ref2 = weakref.ref(o, self.callback)
         del ref1
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(weakref.getweakrefs(o), [ref2],
                      "list of refs does not match")
 
@@ -500,10 +509,12 @@ class ReferencesTestCase(TestBase):
         ref1 = weakref.ref(o, self.callback)
         ref2 = weakref.ref(o, self.callback)
         del ref2
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(weakref.getweakrefs(o), [ref1],
                      "list of refs does not match")
 
         del ref1
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(weakref.getweakrefs(o), [],
                      "list of refs not cleared")
 
@@ -989,6 +1000,7 @@ class SubclassableWeakrefTestCase(TestBase):
         self.assertTrue(mr.called)
         self.assertEqual(mr.value, 24)
         del o
+        gc_collect()  # For PyPy or other GCs.
         self.assertIsNone(mr())
         self.assertTrue(mr.called)
 
@@ -1291,15 +1303,18 @@ class MappingTestCase(TestBase):
         del items1, items2
         self.assertEqual(len(dict), self.COUNT)
         del objects[0]
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(dict), self.COUNT - 1,
                      "deleting object did not cause dictionary update")
         del objects, o
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(dict), 0,
                      "deleting the values did not clear the dictionary")
         # regression on SF bug #447152:
         dict = weakref.WeakValueDictionary()
         self.assertRaises(KeyError, dict.__getitem__, 1)
         dict[2] = C()
+        gc_collect()  # For PyPy or other GCs.
         self.assertRaises(KeyError, dict.__getitem__, 2)
 
     def test_weak_keys(self):
@@ -1320,9 +1335,11 @@ class MappingTestCase(TestBase):
         del items1, items2
         self.assertEqual(len(dict), self.COUNT)
         del objects[0]
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(dict), (self.COUNT - 1),
                      "deleting object did not cause dictionary update")
         del objects, o
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(dict), 0,
                      "deleting the keys did not clear the dictionary")
         o = Object(42)
@@ -1821,6 +1838,7 @@ class MappingTestCase(TestBase):
         for o in objs:
             count += 1
             del d[o]
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(d), 0)
         self.assertEqual(count, 2)
 
@@ -2129,6 +2147,7 @@ class FinalizeTestCase(unittest.TestCase):
 
 libreftest = """ Doctest for examples in the library reference: weakref.rst
 
+>>> from test.support import gc_collect
 >>> import weakref
 >>> class Dict(dict):
 ...     pass
@@ -2148,6 +2167,7 @@ True
 >>> o is o2
 True
 >>> del o, o2
+>>> gc_collect()  # For PyPy or other GCs.
 >>> print(r())
 None
 
@@ -2200,6 +2220,7 @@ True
 >>> id2obj(a_id) is a
 True
 >>> del a
+>>> gc_collect()  # For PyPy or other GCs.
 >>> try:
 ...     id2obj(a_id)
 ... except KeyError:
diff --git a/Lib/test/test_weakset.py b/Lib/test/test_weakset.py
index 49a9b5c..9b31d5f 100644
--- a/Lib/test/test_weakset.py
+++ b/Lib/test/test_weakset.py
@@ -5,6 +5,7 @@ from collections import UserString as ustr
 from collections.abc import Set, MutableSet
 import gc
 import contextlib
+from test import support
 
 
 class Foo:
@@ -48,6 +49,7 @@ class TestWeakSet(unittest.TestCase):
         self.assertEqual(len(self.s), len(self.d))
         self.assertEqual(len(self.fs), 1)
         del self.obj
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertEqual(len(self.fs), 0)
 
     def test_contains(self):
@@ -57,6 +59,7 @@ class TestWeakSet(unittest.TestCase):
         self.assertNotIn(1, self.s)
         self.assertIn(self.obj, self.fs)
         del self.obj
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertNotIn(ustr('F'), self.fs)
 
     def test_union(self):
@@ -215,6 +218,7 @@ class TestWeakSet(unittest.TestCase):
         self.assertEqual(self.s, dup)
         self.assertRaises(TypeError, self.s.add, [])
         self.fs.add(Foo())
+        support.gc_collect()  # For PyPy or other GCs.
         self.assertTrue(len(self.fs) == 1)
         self.fs.add(self.obj)
         self.assertTrue(len(self.fs) == 1)
@@ -406,6 +410,7 @@ class TestWeakSet(unittest.TestCase):
         n1 = len(s)
         del it
         gc.collect()
+        gc.collect()  # For PyPy or other GCs.
         n2 = len(s)
         # one item may be kept alive inside the iterator
         self.assertIn(n1, (0, 1))
diff --git a/Lib/test/test_xml_etree.py b/Lib/test/test_xml_etree.py
index 553529a..c79b546 100644
--- a/Lib/test/test_xml_etree.py
+++ b/Lib/test/test_xml_etree.py
@@ -2480,6 +2480,7 @@ class BasicElementTest(ElementTestCase, unittest.TestCase):
         wref = weakref.ref(e, wref_cb)
         self.assertEqual(wref().tag, 'e')
         del e
+        gc_collect()  # For PyPy or other GCs.
         self.assertEqual(flag, True)
         self.assertEqual(wref(), None)