diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py
new file mode 100644
index 0000000000..b8152b1b46
--- /dev/null
+++ b/Lib/test/test_warnings/__init__.py
@@ -0,0 +1,1983 @@
+from contextlib import contextmanager
+import linecache
+import os
+import importlib
+import inspect
+from io import StringIO
+import re
+import sys
+import textwrap
+import types
+from typing import overload, get_overloads
+import unittest
+from test import support
+from test.support import import_helper
+from test.support import os_helper
+from test.support import warnings_helper
+from test.support import force_not_colorized
+from test.support.script_helper import assert_python_ok, assert_python_failure
+
+from test.test_warnings.data import package_helper
+from test.test_warnings.data import stacklevel as warning_tests
+
+import warnings as original_warnings
+from warnings import deprecated
+
+
+py_warnings = import_helper.import_fresh_module('warnings',
+                                                blocked=['_warnings'])
+c_warnings = import_helper.import_fresh_module('warnings',
+                                               fresh=['_warnings'])
+
+@contextmanager
+def warnings_state(module):
+    """Use a specific warnings implementation in warning_tests."""
+    global __warningregistry__
+    for to_clear in (sys, warning_tests):
+        try:
+            to_clear.__warningregistry__.clear()
+        except AttributeError:
+            pass
+    try:
+        __warningregistry__.clear()
+    except NameError:
+        pass
+    original_warnings = warning_tests.warnings
+    original_filters = module.filters
+    try:
+        module.filters = original_filters[:]
+        module.simplefilter("once")
+        warning_tests.warnings = module
+        yield
+    finally:
+        warning_tests.warnings = original_warnings
+        module.filters = original_filters
+
+
+class TestWarning(Warning):
+    pass
+
+
+class BaseTest:
+
+    """Basic bookkeeping required for testing."""
+
+    def setUp(self):
+        self.old_unittest_module = unittest.case.warnings
+        # The __warningregistry__ needs to be in a pristine state for tests
+        # to work properly.
+        if '__warningregistry__' in globals():
+            del globals()['__warningregistry__']
+        if hasattr(warning_tests, '__warningregistry__'):
+            del warning_tests.__warningregistry__
+        if hasattr(sys, '__warningregistry__'):
+            del sys.__warningregistry__
+        # The 'warnings' module must be explicitly set so that the proper
+        # interaction between _warnings and 'warnings' can be controlled.
+        sys.modules['warnings'] = self.module
+        # Ensure that unittest.TestCase.assertWarns() uses the same warnings
+        # module than warnings.catch_warnings(). Otherwise,
+        # warnings.catch_warnings() will be unable to remove the added filter.
+        unittest.case.warnings = self.module
+        super(BaseTest, self).setUp()
+
+    def tearDown(self):
+        sys.modules['warnings'] = original_warnings
+        unittest.case.warnings = self.old_unittest_module
+        super(BaseTest, self).tearDown()
+
+class PublicAPITests(BaseTest):
+
+    """Ensures that the correct values are exposed in the
+    public API.
+    """
+
+    def test_module_all_attribute(self):
+        self.assertTrue(hasattr(self.module, '__all__'))
+        target_api = ["warn", "warn_explicit", "showwarning",
+                      "formatwarning", "filterwarnings", "simplefilter",
+                      "resetwarnings", "catch_warnings", "deprecated"]
+        self.assertSetEqual(set(self.module.__all__),
+                            set(target_api))
+
+class CPublicAPITests(PublicAPITests, unittest.TestCase):
+    module = c_warnings
+
+class PyPublicAPITests(PublicAPITests, unittest.TestCase):
+    module = py_warnings
+
+class FilterTests(BaseTest):
+
+    """Testing the filtering functionality."""
+
+    def test_error(self):
+        with original_warnings.catch_warnings(module=self.module) as w:
+            self.module.resetwarnings()
+            self.module.filterwarnings("error", category=UserWarning)
+            self.assertRaises(UserWarning, self.module.warn,
+                                "FilterTests.test_error")
+
+    def test_error_after_default(self):
+        with original_warnings.catch_warnings(module=self.module) as w:
+            self.module.resetwarnings()
+            message = "FilterTests.test_ignore_after_default"
+            def f():
+                self.module.warn(message, UserWarning)
+
+            with support.captured_stderr() as stderr:
+                f()
+            stderr = stderr.getvalue()
+            self.assertIn("UserWarning: FilterTests.test_ignore_after_default",
+                          stderr)
+            self.assertIn("self.module.warn(message, UserWarning)",
+                          stderr)
+
+            self.module.filterwarnings("error", category=UserWarning)
+            self.assertRaises(UserWarning, f)
+
+    def test_ignore(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.resetwarnings()
+            self.module.filterwarnings("ignore", category=UserWarning)
+            self.module.warn("FilterTests.test_ignore", UserWarning)
+            self.assertEqual(len(w), 0)
+            self.assertEqual(list(__warningregistry__), ['version'])
+
+    def test_ignore_after_default(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.resetwarnings()
+            message = "FilterTests.test_ignore_after_default"
+            def f():
+                self.module.warn(message, UserWarning)
+            f()
+            self.module.filterwarnings("ignore", category=UserWarning)
+            f()
+            f()
+            self.assertEqual(len(w), 1)
+
+    def test_always(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.resetwarnings()
+            self.module.filterwarnings("always", category=UserWarning)
+            message = "FilterTests.test_always"
+            def f():
+                self.module.warn(message, UserWarning)
+            f()
+            self.assertEqual(len(w), 1)
+            self.assertEqual(w[-1].message.args[0], message)
+            f()
+            self.assertEqual(len(w), 2)
+            self.assertEqual(w[-1].message.args[0], message)
+
+    def test_always_after_default(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.resetwarnings()
+            message = "FilterTests.test_always_after_ignore"
+            def f():
+                self.module.warn(message, UserWarning)
+            f()
+            self.assertEqual(len(w), 1)
+            self.assertEqual(w[-1].message.args[0], message)
+            f()
+            self.assertEqual(len(w), 1)
+            self.module.filterwarnings("always", category=UserWarning)
+            f()
+            self.assertEqual(len(w), 2)
+            self.assertEqual(w[-1].message.args[0], message)
+            f()
+            self.assertEqual(len(w), 3)
+            self.assertEqual(w[-1].message.args[0], message)
+
+    def test_default(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.resetwarnings()
+            self.module.filterwarnings("default", category=UserWarning)
+            message = UserWarning("FilterTests.test_default")
+            for x in range(2):
+                self.module.warn(message, UserWarning)
+                if x == 0:
+                    self.assertEqual(w[-1].message, message)
+                    del w[:]
+                elif x == 1:
+                    self.assertEqual(len(w), 0)
+                else:
+                    raise ValueError("loop variant unhandled")
+
+    def test_module(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.resetwarnings()
+            self.module.filterwarnings("module", category=UserWarning)
+            message = UserWarning("FilterTests.test_module")
+            self.module.warn(message, UserWarning)
+            self.assertEqual(w[-1].message, message)
+            del w[:]
+            self.module.warn(message, UserWarning)
+            self.assertEqual(len(w), 0)
+
+    def test_once(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.resetwarnings()
+            self.module.filterwarnings("once", category=UserWarning)
+            message = UserWarning("FilterTests.test_once")
+            self.module.warn_explicit(message, UserWarning, "__init__.py",
+                                    42)
+            self.assertEqual(w[-1].message, message)
+            del w[:]
+            self.module.warn_explicit(message, UserWarning, "__init__.py",
+                                    13)
+            self.assertEqual(len(w), 0)
+            self.module.warn_explicit(message, UserWarning, "test_warnings2.py",
+                                    42)
+            self.assertEqual(len(w), 0)
+
+    def test_module_globals(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.simplefilter("always", UserWarning)
+
+            # bpo-33509: module_globals=None must not crash
+            self.module.warn_explicit('msg', UserWarning, "filename", 42,
+                                      module_globals=None)
+            self.assertEqual(len(w), 1)
+
+            # Invalid module_globals type
+            with self.assertRaises(TypeError):
+                self.module.warn_explicit('msg', UserWarning, "filename", 42,
+                                          module_globals=True)
+            self.assertEqual(len(w), 1)
+
+            # Empty module_globals
+            self.module.warn_explicit('msg', UserWarning, "filename", 42,
+                                      module_globals={})
+            self.assertEqual(len(w), 2)
+
+    def test_inheritance(self):
+        with original_warnings.catch_warnings(module=self.module) as w:
+            self.module.resetwarnings()
+            self.module.filterwarnings("error", category=Warning)
+            self.assertRaises(UserWarning, self.module.warn,
+                                "FilterTests.test_inheritance", UserWarning)
+
+    def test_ordering(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.resetwarnings()
+            self.module.filterwarnings("ignore", category=UserWarning)
+            self.module.filterwarnings("error", category=UserWarning,
+                                        append=True)
+            del w[:]
+            try:
+                self.module.warn("FilterTests.test_ordering", UserWarning)
+            except UserWarning:
+                self.fail("order handling for actions failed")
+            self.assertEqual(len(w), 0)
+
+    def test_filterwarnings(self):
+        # Test filterwarnings().
+        # Implicitly also tests resetwarnings().
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.filterwarnings("error", "", Warning, "", 0)
+            self.assertRaises(UserWarning, self.module.warn, 'convert to error')
+
+            self.module.resetwarnings()
+            text = 'handle normally'
+            self.module.warn(text)
+            self.assertEqual(str(w[-1].message), text)
+            self.assertIs(w[-1].category, UserWarning)
+
+            self.module.filterwarnings("ignore", "", Warning, "", 0)
+            text = 'filtered out'
+            self.module.warn(text)
+            self.assertNotEqual(str(w[-1].message), text)
+
+            self.module.resetwarnings()
+            self.module.filterwarnings("error", "hex*", Warning, "", 0)
+            self.assertRaises(UserWarning, self.module.warn, 'hex/oct')
+            text = 'nonmatching text'
+            self.module.warn(text)
+            self.assertEqual(str(w[-1].message), text)
+            self.assertIs(w[-1].category, UserWarning)
+
+    def test_message_matching(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.simplefilter("ignore", UserWarning)
+            self.module.filterwarnings("error", "match", UserWarning)
+            self.assertRaises(UserWarning, self.module.warn, "match")
+            self.assertRaises(UserWarning, self.module.warn, "match prefix")
+            self.module.warn("suffix match")
+            self.assertEqual(w, [])
+            self.module.warn("something completely different")
+            self.assertEqual(w, [])
+
+    def test_mutate_filter_list(self):
+        class X:
+            def match(self, a):
+                L[:] = []
+
+        L = [("default",X(),UserWarning,X(),0) for i in range(2)]
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.filters = L
+            self.module.warn_explicit(UserWarning("b"), None, "f.py", 42)
+            self.assertEqual(str(w[-1].message), "b")
+
+    def test_filterwarnings_duplicate_filters(self):
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.resetwarnings()
+            self.module.filterwarnings("error", category=UserWarning)
+            self.assertEqual(len(self.module.filters), 1)
+            self.module.filterwarnings("ignore", category=UserWarning)
+            self.module.filterwarnings("error", category=UserWarning)
+            self.assertEqual(
+                len(self.module.filters), 2,
+                "filterwarnings inserted duplicate filter"
+            )
+            self.assertEqual(
+                self.module.filters[0][0], "error",
+                "filterwarnings did not promote filter to "
+                "the beginning of list"
+            )
+
+    def test_simplefilter_duplicate_filters(self):
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.resetwarnings()
+            self.module.simplefilter("error", category=UserWarning)
+            self.assertEqual(len(self.module.filters), 1)
+            self.module.simplefilter("ignore", category=UserWarning)
+            self.module.simplefilter("error", category=UserWarning)
+            self.assertEqual(
+                len(self.module.filters), 2,
+                "simplefilter inserted duplicate filter"
+            )
+            self.assertEqual(
+                self.module.filters[0][0], "error",
+                "simplefilter did not promote filter to the beginning of list"
+            )
+
+    def test_append_duplicate(self):
+        with original_warnings.catch_warnings(module=self.module,
+                record=True) as w:
+            self.module.resetwarnings()
+            self.module.simplefilter("ignore")
+            self.module.simplefilter("error", append=True)
+            self.module.simplefilter("ignore", append=True)
+            self.module.warn("test_append_duplicate", category=UserWarning)
+            self.assertEqual(len(self.module.filters), 2,
+                "simplefilter inserted duplicate filter"
+            )
+            self.assertEqual(len(w), 0,
+                "appended duplicate changed order of filters"
+            )
+
+    def test_argument_validation(self):
+        with self.assertRaises(ValueError):
+            self.module.filterwarnings(action='foo')
+        with self.assertRaises(TypeError):
+            self.module.filterwarnings('ignore', message=0)
+        with self.assertRaises(TypeError):
+            self.module.filterwarnings('ignore', category=0)
+        with self.assertRaises(TypeError):
+            self.module.filterwarnings('ignore', category=int)
+        with self.assertRaises(TypeError):
+            self.module.filterwarnings('ignore', module=0)
+        with self.assertRaises(TypeError):
+            self.module.filterwarnings('ignore', lineno=int)
+        with self.assertRaises(ValueError):
+            self.module.filterwarnings('ignore', lineno=-1)
+        with self.assertRaises(ValueError):
+            self.module.simplefilter(action='foo')
+        with self.assertRaises(TypeError):
+            self.module.simplefilter('ignore', lineno=int)
+        with self.assertRaises(ValueError):
+            self.module.simplefilter('ignore', lineno=-1)
+
+    def test_catchwarnings_with_simplefilter_ignore(self):
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.resetwarnings()
+            self.module.simplefilter("error")
+            with self.module.catch_warnings(
+                module=self.module, action="ignore"
+            ):
+                self.module.warn("This will be ignored")
+
+    def test_catchwarnings_with_simplefilter_error(self):
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.resetwarnings()
+            with self.module.catch_warnings(
+                module=self.module, action="error", category=FutureWarning
+            ):
+                with support.captured_stderr() as stderr:
+                    error_msg = "Other types of warnings are not errors"
+                    self.module.warn(error_msg)
+                    self.assertRaises(FutureWarning,
+                                      self.module.warn, FutureWarning("msg"))
+                    stderr = stderr.getvalue()
+                    self.assertIn(error_msg, stderr)
+
+class CFilterTests(FilterTests, unittest.TestCase):
+    module = c_warnings
+
+class PyFilterTests(FilterTests, unittest.TestCase):
+    module = py_warnings
+
+
+class WarnTests(BaseTest):
+
+    """Test warnings.warn() and warnings.warn_explicit()."""
+
+    def test_message(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.simplefilter("once")
+            for i in range(4):
+                text = 'multi %d' %i  # Different text on each call.
+                self.module.warn(text)
+                self.assertEqual(str(w[-1].message), text)
+                self.assertIs(w[-1].category, UserWarning)
+
+    # Issue 3639
+    def test_warn_nonstandard_types(self):
+        # warn() should handle non-standard types without issue.
+        for ob in (Warning, None, 42):
+            with original_warnings.catch_warnings(record=True,
+                    module=self.module) as w:
+                self.module.simplefilter("once")
+                self.module.warn(ob)
+                # Don't directly compare objects since
+                # ``Warning() != Warning()``.
+                self.assertEqual(str(w[-1].message), str(UserWarning(ob)))
+
+    def test_filename(self):
+        with warnings_state(self.module):
+            with original_warnings.catch_warnings(record=True,
+                    module=self.module) as w:
+                warning_tests.inner("spam1")
+                self.assertEqual(os.path.basename(w[-1].filename),
+                                    "stacklevel.py")
+                warning_tests.outer("spam2")
+                self.assertEqual(os.path.basename(w[-1].filename),
+                                    "stacklevel.py")
+
+    def test_stacklevel(self):
+        # Test stacklevel argument
+        # make sure all messages are different, so the warning won't be skipped
+        with warnings_state(self.module):
+            with original_warnings.catch_warnings(record=True,
+                    module=self.module) as w:
+                warning_tests.inner("spam3", stacklevel=1)
+                self.assertEqual(os.path.basename(w[-1].filename),
+                                    "stacklevel.py")
+                warning_tests.outer("spam4", stacklevel=1)
+                self.assertEqual(os.path.basename(w[-1].filename),
+                                    "stacklevel.py")
+
+                warning_tests.inner("spam5", stacklevel=2)
+                self.assertEqual(os.path.basename(w[-1].filename),
+                                    "__init__.py")
+                warning_tests.outer("spam6", stacklevel=2)
+                self.assertEqual(os.path.basename(w[-1].filename),
+                                    "stacklevel.py")
+                warning_tests.outer("spam6.5", stacklevel=3)
+                self.assertEqual(os.path.basename(w[-1].filename),
+                                    "__init__.py")
+
+                warning_tests.inner("spam7", stacklevel=9999)
+                self.assertEqual(os.path.basename(w[-1].filename),
+                                    "<sys>")
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_stacklevel_import(self):
+        # Issue #24305: With stacklevel=2, module-level warnings should work.
+        import_helper.unload('test.test_warnings.data.import_warning')
+        with warnings_state(self.module):
+            with original_warnings.catch_warnings(record=True,
+                    module=self.module) as w:
+                self.module.simplefilter('always')
+                import test.test_warnings.data.import_warning
+                self.assertEqual(len(w), 1)
+                self.assertEqual(w[0].filename, __file__)
+
+    def test_skip_file_prefixes(self):
+        with warnings_state(self.module):
+            with original_warnings.catch_warnings(record=True,
+                    module=self.module) as w:
+                self.module.simplefilter('always')
+
+                # Warning never attributed to the data/ package.
+                package_helper.inner_api(
+                        "inner_api", stacklevel=2,
+                        warnings_module=warning_tests.warnings)
+                self.assertEqual(w[-1].filename, __file__)
+                warning_tests.package("package api", stacklevel=2)
+                self.assertEqual(w[-1].filename, __file__)
+                self.assertEqual(w[-2].filename, w[-1].filename)
+                # Low stacklevels are overridden to 2 behavior.
+                warning_tests.package("package api 1", stacklevel=1)
+                self.assertEqual(w[-1].filename, __file__)
+                warning_tests.package("package api 0", stacklevel=0)
+                self.assertEqual(w[-1].filename, __file__)
+                warning_tests.package("package api -99", stacklevel=-99)
+                self.assertEqual(w[-1].filename, __file__)
+
+                # The stacklevel still goes up out of the package.
+                warning_tests.package("prefix02", stacklevel=3)
+                self.assertIn("unittest", w[-1].filename)
+
+    def test_skip_file_prefixes_type_errors(self):
+        with warnings_state(self.module):
+            warn = warning_tests.warnings.warn
+            with self.assertRaises(TypeError):
+                warn("msg", skip_file_prefixes=[])
+            with self.assertRaises(TypeError):
+                warn("msg", skip_file_prefixes=(b"bytes",))
+            with self.assertRaises(TypeError):
+                warn("msg", skip_file_prefixes="a sequence of strs")
+
+    def test_exec_filename(self):
+        filename = "<warnings-test>"
+        codeobj = compile(("import warnings\n"
+                           "warnings.warn('hello', UserWarning)"),
+                          filename, "exec")
+        with original_warnings.catch_warnings(record=True) as w:
+            self.module.simplefilter("always", category=UserWarning)
+            exec(codeobj)
+        self.assertEqual(w[0].filename, filename)
+
+    def test_warn_explicit_non_ascii_filename(self):
+        with original_warnings.catch_warnings(record=True,
+                module=self.module) as w:
+            self.module.resetwarnings()
+            self.module.filterwarnings("always", category=UserWarning)
+            filenames = ["nonascii\xe9\u20ac"]
+            if not support.is_emscripten:
+                # JavaScript does not like surrogates.
+                # Invalid UTF-8 leading byte 0x80 encountered when
+                # deserializing a UTF-8 string in wasm memory to a JS
+                # string!
+                filenames.append("surrogate\udc80")
+            for filename in filenames:
+                try:
+                    os.fsencode(filename)
+                except UnicodeEncodeError:
+                    continue
+                self.module.warn_explicit("text", UserWarning, filename, 1)
+                self.assertEqual(w[-1].filename, filename)
+
+    def test_warn_explicit_type_errors(self):
+        # warn_explicit() should error out gracefully if it is given objects
+        # of the wrong types.
+        # lineno is expected to be an integer.
+        self.assertRaises(TypeError, self.module.warn_explicit,
+                            None, UserWarning, None, None)
+        # Either 'message' needs to be an instance of Warning or 'category'
+        # needs to be a subclass.
+        self.assertRaises(TypeError, self.module.warn_explicit,
+                            None, None, None, 1)
+        # 'registry' must be a dict or None.
+        self.assertRaises((TypeError, AttributeError),
+                            self.module.warn_explicit,
+                            None, Warning, None, 1, registry=42)
+
+    def test_bad_str(self):
+        # issue 6415
+        # Warnings instance with a bad format string for __str__ should not
+        # trigger a bus error.
+        class BadStrWarning(Warning):
+            """Warning with a bad format string for __str__."""
+            def __str__(self):
+                return ("A bad formatted string %(err)" %
+                        {"err" : "there is no %(err)s"})
+
+        with self.assertRaises(ValueError):
+            self.module.warn(BadStrWarning())
+
+    def test_warning_classes(self):
+        class MyWarningClass(Warning):
+            pass
+
+        class NonWarningSubclass:
+            pass
+
+        # passing a non-subclass of Warning should raise a TypeError
+        with self.assertRaises(TypeError) as cm:
+            self.module.warn('bad warning category', '')
+        self.assertIn('category must be a Warning subclass, not ',
+                      str(cm.exception))
+
+        with self.assertRaises(TypeError) as cm:
+            self.module.warn('bad warning category', NonWarningSubclass)
+        self.assertIn('category must be a Warning subclass, not ',
+                      str(cm.exception))
+
+        # check that warning instances also raise a TypeError
+        with self.assertRaises(TypeError) as cm:
+            self.module.warn('bad warning category', MyWarningClass())
+        self.assertIn('category must be a Warning subclass, not ',
+                      str(cm.exception))
+
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.resetwarnings()
+            self.module.filterwarnings('default')
+            with self.assertWarns(MyWarningClass) as cm:
+                self.module.warn('good warning category', MyWarningClass)
+            self.assertEqual('good warning category', str(cm.warning))
+
+            with self.assertWarns(UserWarning) as cm:
+                self.module.warn('good warning category', None)
+            self.assertEqual('good warning category', str(cm.warning))
+
+            with self.assertWarns(MyWarningClass) as cm:
+                self.module.warn('good warning category', MyWarningClass)
+            self.assertIsInstance(cm.warning, Warning)
+
+    def check_module_globals(self, module_globals):
+        with original_warnings.catch_warnings(module=self.module, record=True) as w:
+            self.module.filterwarnings('default')
+            self.module.warn_explicit(
+                'eggs', UserWarning, 'bar', 1,
+                module_globals=module_globals)
+        self.assertEqual(len(w), 1)
+        self.assertEqual(w[0].category, UserWarning)
+        self.assertEqual(str(w[0].message), 'eggs')
+
+    def check_module_globals_error(self, module_globals, errmsg, errtype=ValueError):
+        if self.module is py_warnings:
+            self.check_module_globals(module_globals)
+            return
+        with original_warnings.catch_warnings(module=self.module, record=True) as w:
+            self.module.filterwarnings('always')
+            with self.assertRaisesRegex(errtype, re.escape(errmsg)):
+                self.module.warn_explicit(
+                    'eggs', UserWarning, 'bar', 1,
+                    module_globals=module_globals)
+        self.assertEqual(len(w), 0)
+
+    def check_module_globals_deprecated(self, module_globals, msg):
+        if self.module is py_warnings:
+            self.check_module_globals(module_globals)
+            return
+        with original_warnings.catch_warnings(module=self.module, record=True) as w:
+            self.module.filterwarnings('always')
+            self.module.warn_explicit(
+                'eggs', UserWarning, 'bar', 1,
+                module_globals=module_globals)
+        self.assertEqual(len(w), 2)
+        self.assertEqual(w[0].category, DeprecationWarning)
+        self.assertEqual(str(w[0].message), msg)
+        self.assertEqual(w[1].category, UserWarning)
+        self.assertEqual(str(w[1].message), 'eggs')
+
+    def test_gh86298_no_loader_and_no_spec(self):
+        self.check_module_globals({'__name__': 'bar'})
+
+    def test_gh86298_loader_is_none_and_no_spec(self):
+        self.check_module_globals({'__name__': 'bar', '__loader__': None})
+
+    def test_gh86298_no_loader_and_spec_is_none(self):
+        self.check_module_globals_error(
+            {'__name__': 'bar', '__spec__': None},
+            'Module globals is missing a __spec__.loader')
+
+    def test_gh86298_loader_is_none_and_spec_is_none(self):
+        self.check_module_globals_error(
+            {'__name__': 'bar', '__loader__': None, '__spec__': None},
+            'Module globals is missing a __spec__.loader')
+
+    def test_gh86298_loader_is_none_and_spec_loader_is_none(self):
+        self.check_module_globals_error(
+            {'__name__': 'bar', '__loader__': None,
+             '__spec__': types.SimpleNamespace(loader=None)},
+            'Module globals is missing a __spec__.loader')
+
+    def test_gh86298_no_spec(self):
+        self.check_module_globals_deprecated(
+            {'__name__': 'bar', '__loader__': object()},
+            'Module globals is missing a __spec__.loader')
+
+    def test_gh86298_spec_is_none(self):
+        self.check_module_globals_deprecated(
+            {'__name__': 'bar', '__loader__': object(), '__spec__': None},
+            'Module globals is missing a __spec__.loader')
+
+    def test_gh86298_no_spec_loader(self):
+        self.check_module_globals_deprecated(
+            {'__name__': 'bar', '__loader__': object(),
+             '__spec__': types.SimpleNamespace()},
+            'Module globals is missing a __spec__.loader')
+
+    def test_gh86298_loader_and_spec_loader_disagree(self):
+        self.check_module_globals_deprecated(
+            {'__name__': 'bar', '__loader__': object(),
+             '__spec__': types.SimpleNamespace(loader=object())},
+            'Module globals; __loader__ != __spec__.loader')
+
+    def test_gh86298_no_loader_and_no_spec_loader(self):
+        self.check_module_globals_error(
+            {'__name__': 'bar', '__spec__': types.SimpleNamespace()},
+            'Module globals is missing a __spec__.loader', AttributeError)
+
+    def test_gh86298_no_loader_with_spec_loader_okay(self):
+        self.check_module_globals(
+            {'__name__': 'bar',
+             '__spec__': types.SimpleNamespace(loader=object())})
+
+class CWarnTests(WarnTests, unittest.TestCase):
+    module = c_warnings
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    # As an early adopter, we sanity check the
+    # test.import_helper.import_fresh_module utility function
+    def test_accelerated(self):
+        self.assertIsNot(original_warnings, self.module)
+        self.assertFalse(hasattr(self.module.warn, '__code__'))
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_gh86298_no_loader_and_spec_is_none(self):
+        return super().test_gh86298_no_loader_and_spec_is_none()
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_gh86298_loader_is_none_and_spec_is_none(self):
+        return super().test_gh86298_loader_is_none_and_spec_is_none()
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_gh86298_loader_is_none_and_spec_loader_is_none(self):
+        return super().test_gh86298_loader_is_none_and_spec_loader_is_none()
+    
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_gh86298_no_spec(self):
+        return super().test_gh86298_no_spec()
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_gh86298_spec_is_none(self):
+        return super().test_gh86298_spec_is_none()
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_gh86298_no_spec_loader(self):
+        return super().test_gh86298_no_spec_loader()
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_gh86298_loader_and_spec_loader_disagree(self):
+        return super().test_gh86298_loader_and_spec_loader_disagree()
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_gh86298_no_loader_and_no_spec_loader(self):
+        return super().test_gh86298_no_loader_and_no_spec_loader()
+
+class PyWarnTests(WarnTests, unittest.TestCase):
+    module = py_warnings
+
+    # As an early adopter, we sanity check the
+    # test.import_helper.import_fresh_module utility function
+    def test_pure_python(self):
+        self.assertIsNot(original_warnings, self.module)
+        self.assertTrue(hasattr(self.module.warn, '__code__'))
+
+
+class WCmdLineTests(BaseTest):
+
+    def test_improper_input(self):
+        # Uses the private _setoption() function to test the parsing
+        # of command-line warning arguments
+        with original_warnings.catch_warnings(module=self.module):
+            self.assertRaises(self.module._OptionError,
+                              self.module._setoption, '1:2:3:4:5:6')
+            self.assertRaises(self.module._OptionError,
+                              self.module._setoption, 'bogus::Warning')
+            self.assertRaises(self.module._OptionError,
+                              self.module._setoption, 'ignore:2::4:-5')
+            with self.assertRaises(self.module._OptionError):
+                self.module._setoption('ignore::123')
+            with self.assertRaises(self.module._OptionError):
+                self.module._setoption('ignore::123abc')
+            with self.assertRaises(self.module._OptionError):
+                self.module._setoption('ignore::===')
+            with self.assertRaisesRegex(self.module._OptionError, 'Wärning'):
+                self.module._setoption('ignore::Wärning')
+            self.module._setoption('error::Warning::0')
+            self.assertRaises(UserWarning, self.module.warn, 'convert to error')
+
+    def test_import_from_module(self):
+        with original_warnings.catch_warnings(module=self.module):
+            self.module._setoption('ignore::Warning')
+            with self.assertRaises(self.module._OptionError):
+                self.module._setoption('ignore::TestWarning')
+            with self.assertRaises(self.module._OptionError):
+                self.module._setoption('ignore::test.test_warnings.bogus')
+            self.module._setoption('error::test.test_warnings.TestWarning')
+            with self.assertRaises(TestWarning):
+                self.module.warn('test warning', TestWarning)
+
+
+class CWCmdLineTests(WCmdLineTests, unittest.TestCase):
+    module = c_warnings
+
+
+class PyWCmdLineTests(WCmdLineTests, unittest.TestCase):
+    module = py_warnings
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_improper_option(self):
+        # Same as above, but check that the message is printed out when
+        # the interpreter is executed. This also checks that options are
+        # actually parsed at all.
+        rc, out, err = assert_python_ok("-Wxxx", "-c", "pass")
+        self.assertIn(b"Invalid -W option ignored: invalid action: 'xxx'", err)
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_warnings_bootstrap(self):
+        # Check that the warnings module does get loaded when -W<some option>
+        # is used (see issue #10372 for an example of silent bootstrap failure).
+        rc, out, err = assert_python_ok("-Wi", "-c",
+            "import sys; sys.modules['warnings'].warn('foo', RuntimeWarning)")
+        # '-Wi' was observed
+        self.assertFalse(out.strip())
+        self.assertNotIn(b'RuntimeWarning', err)
+
+
+class _WarningsTests(BaseTest, unittest.TestCase):
+
+    """Tests specific to the _warnings module."""
+
+    module = c_warnings
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_filter(self):
+        # Everything should function even if 'filters' is not in warnings.
+        with original_warnings.catch_warnings(module=self.module) as w:
+            self.module.filterwarnings("error", "", Warning, "", 0)
+            self.assertRaises(UserWarning, self.module.warn,
+                                'convert to error')
+            del self.module.filters
+            self.assertRaises(UserWarning, self.module.warn,
+                                'convert to error')
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_onceregistry(self):
+        # Replacing or removing the onceregistry should be okay.
+        global __warningregistry__
+        message = UserWarning('onceregistry test')
+        try:
+            original_registry = self.module.onceregistry
+            __warningregistry__ = {}
+            with original_warnings.catch_warnings(record=True,
+                    module=self.module) as w:
+                self.module.resetwarnings()
+                self.module.filterwarnings("once", category=UserWarning)
+                self.module.warn_explicit(message, UserWarning, "file", 42)
+                self.assertEqual(w[-1].message, message)
+                del w[:]
+                self.module.warn_explicit(message, UserWarning, "file", 42)
+                self.assertEqual(len(w), 0)
+                # Test the resetting of onceregistry.
+                self.module.onceregistry = {}
+                __warningregistry__ = {}
+                self.module.warn('onceregistry test')
+                self.assertEqual(w[-1].message.args, message.args)
+                # Removal of onceregistry is okay.
+                del w[:]
+                del self.module.onceregistry
+                __warningregistry__ = {}
+                self.module.warn_explicit(message, UserWarning, "file", 42)
+                self.assertEqual(len(w), 0)
+        finally:
+            self.module.onceregistry = original_registry
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_default_action(self):
+        # Replacing or removing defaultaction should be okay.
+        message = UserWarning("defaultaction test")
+        original = self.module.defaultaction
+        try:
+            with original_warnings.catch_warnings(record=True,
+                    module=self.module) as w:
+                self.module.resetwarnings()
+                registry = {}
+                self.module.warn_explicit(message, UserWarning, "<test>", 42,
+                                            registry=registry)
+                self.assertEqual(w[-1].message, message)
+                self.assertEqual(len(w), 1)
+                # One actual registry key plus the "version" key
+                self.assertEqual(len(registry), 2)
+                self.assertIn("version", registry)
+                del w[:]
+                # Test removal.
+                del self.module.defaultaction
+                __warningregistry__ = {}
+                registry = {}
+                self.module.warn_explicit(message, UserWarning, "<test>", 43,
+                                            registry=registry)
+                self.assertEqual(w[-1].message, message)
+                self.assertEqual(len(w), 1)
+                self.assertEqual(len(registry), 2)
+                del w[:]
+                # Test setting.
+                self.module.defaultaction = "ignore"
+                __warningregistry__ = {}
+                registry = {}
+                self.module.warn_explicit(message, UserWarning, "<test>", 44,
+                                            registry=registry)
+                self.assertEqual(len(w), 0)
+        finally:
+            self.module.defaultaction = original
+
+    def test_showwarning_missing(self):
+        # Test that showwarning() missing is okay.
+        text = 'del showwarning test'
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.filterwarnings("always", category=UserWarning)
+            del self.module.showwarning
+            with support.captured_output('stderr') as stream:
+                self.module.warn(text)
+                result = stream.getvalue()
+        self.assertIn(text, result)
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_showwarnmsg_missing(self):
+        # Test that _showwarnmsg() missing is okay.
+        text = 'del _showwarnmsg test'
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.filterwarnings("always", category=UserWarning)
+
+            show = self.module._showwarnmsg
+            try:
+                del self.module._showwarnmsg
+                with support.captured_output('stderr') as stream:
+                    self.module.warn(text)
+                    result = stream.getvalue()
+            finally:
+                self.module._showwarnmsg = show
+        self.assertIn(text, result)
+
+    def test_showwarning_not_callable(self):
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.filterwarnings("always", category=UserWarning)
+            self.module.showwarning = print
+            with support.captured_output('stdout'):
+                self.module.warn('Warning!')
+            self.module.showwarning = 23
+            self.assertRaises(TypeError, self.module.warn, "Warning!")
+
+    def test_show_warning_output(self):
+        # With showwarning() missing, make sure that output is okay.
+        text = 'test show_warning'
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.filterwarnings("always", category=UserWarning)
+            del self.module.showwarning
+            with support.captured_output('stderr') as stream:
+                warning_tests.inner(text)
+                result = stream.getvalue()
+        self.assertEqual(result.count('\n'), 2,
+                             "Too many newlines in %r" % result)
+        first_line, second_line = result.split('\n', 1)
+        expected_file = os.path.splitext(warning_tests.__file__)[0] + '.py'
+        first_line_parts = first_line.rsplit(':', 3)
+        path, line, warning_class, message = first_line_parts
+        line = int(line)
+        self.assertEqual(expected_file, path)
+        self.assertEqual(warning_class, ' ' + UserWarning.__name__)
+        self.assertEqual(message, ' ' + text)
+        expected_line = '  ' + linecache.getline(path, line).strip() + '\n'
+        assert expected_line
+        self.assertEqual(second_line, expected_line)
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_filename_none(self):
+        # issue #12467: race condition if a warning is emitted at shutdown
+        globals_dict = globals()
+        oldfile = globals_dict['__file__']
+        try:
+            catch = original_warnings.catch_warnings(record=True,
+                                                     module=self.module)
+            with catch as w:
+                self.module.filterwarnings("always", category=UserWarning)
+                globals_dict['__file__'] = None
+                original_warnings.warn('test', UserWarning)
+                self.assertTrue(len(w))
+        finally:
+            globals_dict['__file__'] = oldfile
+
+    def test_stderr_none(self):
+        rc, stdout, stderr = assert_python_ok("-c",
+            "import sys; sys.stderr = None; "
+            "import warnings; warnings.simplefilter('always'); "
+            "warnings.warn('Warning!')")
+        self.assertEqual(stdout, b'')
+        self.assertNotIn(b'Warning!', stderr)
+        self.assertNotIn(b'Error', stderr)
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_issue31285(self):
+        # warn_explicit() should neither raise a SystemError nor cause an
+        # assertion failure, in case the return value of get_source() has a
+        # bad splitlines() method.
+        get_source_called = []
+        def get_module_globals(*, splitlines_ret_val):
+            class BadSource(str):
+                def splitlines(self):
+                    return splitlines_ret_val
+
+            class BadLoader:
+                def get_source(self, fullname):
+                    get_source_called.append(splitlines_ret_val)
+                    return BadSource('spam')
+
+            loader = BadLoader()
+            spec = importlib.machinery.ModuleSpec('foobar', loader)
+            return {'__loader__': loader,
+                    '__spec__': spec,
+                    '__name__': 'foobar'}
+
+
+        wmod = self.module
+        with original_warnings.catch_warnings(module=wmod):
+            wmod.filterwarnings('default', category=UserWarning)
+
+            linecache.clearcache()
+            with support.captured_stderr() as stderr:
+                wmod.warn_explicit(
+                    'foo', UserWarning, 'bar', 1,
+                    module_globals=get_module_globals(splitlines_ret_val=42))
+            self.assertIn('UserWarning: foo', stderr.getvalue())
+            self.assertEqual(get_source_called, [42])
+
+            linecache.clearcache()
+            with support.swap_attr(wmod, '_showwarnmsg', None):
+                del wmod._showwarnmsg
+                with support.captured_stderr() as stderr:
+                    wmod.warn_explicit(
+                        'eggs', UserWarning, 'bar', 1,
+                        module_globals=get_module_globals(splitlines_ret_val=[42]))
+                self.assertIn('UserWarning: eggs', stderr.getvalue())
+            self.assertEqual(get_source_called, [42, [42]])
+            linecache.clearcache()
+
+    @support.cpython_only
+    def test_issue31411(self):
+        # warn_explicit() shouldn't raise a SystemError in case
+        # warnings.onceregistry isn't a dictionary.
+        wmod = self.module
+        with original_warnings.catch_warnings(module=wmod):
+            wmod.filterwarnings('once')
+            with support.swap_attr(wmod, 'onceregistry', None):
+                with self.assertRaises(TypeError):
+                    wmod.warn_explicit('foo', Warning, 'bar', 1, registry=None)
+
+    @support.cpython_only
+    def test_issue31416(self):
+        # warn_explicit() shouldn't cause an assertion failure in case of a
+        # bad warnings.filters or warnings.defaultaction.
+        wmod = self.module
+        with original_warnings.catch_warnings(module=wmod):
+            wmod.filters = [(None, None, Warning, None, 0)]
+            with self.assertRaises(TypeError):
+                wmod.warn_explicit('foo', Warning, 'bar', 1)
+
+            wmod.filters = []
+            with support.swap_attr(wmod, 'defaultaction', None), \
+                 self.assertRaises(TypeError):
+                wmod.warn_explicit('foo', Warning, 'bar', 1)
+
+    @support.cpython_only
+    def test_issue31566(self):
+        # warn() shouldn't cause an assertion failure in case of a bad
+        # __name__ global.
+        with original_warnings.catch_warnings(module=self.module):
+            self.module.filterwarnings('error', category=UserWarning)
+            with support.swap_item(globals(), '__name__', b'foo'), \
+                 support.swap_item(globals(), '__file__', None):
+                self.assertRaises(UserWarning, self.module.warn, 'bar')
+
+
+class WarningsDisplayTests(BaseTest):
+
+    """Test the displaying of warnings and the ability to overload functions
+    related to displaying warnings."""
+
+    def test_formatwarning(self):
+        message = "msg"
+        category = Warning
+        file_name = os.path.splitext(warning_tests.__file__)[0] + '.py'
+        line_num = 5
+        file_line = linecache.getline(file_name, line_num).strip()
+        format = "%s:%s: %s: %s\n  %s\n"
+        expect = format % (file_name, line_num, category.__name__, message,
+                            file_line)
+        self.assertEqual(expect, self.module.formatwarning(message,
+                                                category, file_name, line_num))
+        # Test the 'line' argument.
+        file_line += " for the win!"
+        expect = format % (file_name, line_num, category.__name__, message,
+                            file_line)
+        self.assertEqual(expect, self.module.formatwarning(message,
+                                    category, file_name, line_num, file_line))
+
+    def test_showwarning(self):
+        file_name = os.path.splitext(warning_tests.__file__)[0] + '.py'
+        line_num = 3
+        expected_file_line = linecache.getline(file_name, line_num).strip()
+        message = 'msg'
+        category = Warning
+        file_object = StringIO()
+        expect = self.module.formatwarning(message, category, file_name,
+                                            line_num)
+        self.module.showwarning(message, category, file_name, line_num,
+                                file_object)
+        self.assertEqual(file_object.getvalue(), expect)
+        # Test 'line' argument.
+        expected_file_line += "for the win!"
+        expect = self.module.formatwarning(message, category, file_name,
+                                            line_num, expected_file_line)
+        file_object = StringIO()
+        self.module.showwarning(message, category, file_name, line_num,
+                                file_object, expected_file_line)
+        self.assertEqual(expect, file_object.getvalue())
+
+    def test_formatwarning_override(self):
+        # bpo-35178: Test that a custom formatwarning function gets the 'line'
+        # argument as a positional argument, and not only as a keyword argument
+        def myformatwarning(message, category, filename, lineno, text):
+            return f'm={message}:c={category}:f={filename}:l={lineno}:t={text}'
+
+        file_name = os.path.splitext(warning_tests.__file__)[0] + '.py'
+        line_num = 3
+        file_line = linecache.getline(file_name, line_num).strip()
+        message = 'msg'
+        category = Warning
+        file_object = StringIO()
+        expected = f'm={message}:c={category}:f={file_name}:l={line_num}' + \
+                   f':t={file_line}'
+        with support.swap_attr(self.module, 'formatwarning', myformatwarning):
+            self.module.showwarning(message, category, file_name, line_num,
+                                    file_object, file_line)
+            self.assertEqual(file_object.getvalue(), expected)
+
+
+class CWarningsDisplayTests(WarningsDisplayTests, unittest.TestCase):
+    module = c_warnings
+
+class PyWarningsDisplayTests(WarningsDisplayTests, unittest.TestCase):
+    module = py_warnings
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_tracemalloc(self):
+        self.addCleanup(os_helper.unlink, os_helper.TESTFN)
+
+        with open(os_helper.TESTFN, 'w', encoding="utf-8") as fp:
+            fp.write(textwrap.dedent("""
+                def func():
+                    f = open(__file__, "rb")
+                    # Emit ResourceWarning
+                    f = None
+
+                func()
+            """))
+
+        def run(*args):
+            res = assert_python_ok(*args, PYTHONIOENCODING='utf-8')
+            stderr = res.err.decode('utf-8', 'replace')
+            stderr = '\n'.join(stderr.splitlines())
+
+            # normalize newlines
+            stderr = re.sub('<.*>', '<...>', stderr)
+            return stderr
+
+        # tracemalloc disabled
+        filename = os.path.abspath(os_helper.TESTFN)
+        stderr = run('-Wd', os_helper.TESTFN)
+        expected = textwrap.dedent(f'''
+            {filename}:5: ResourceWarning: unclosed file <...>
+              f = None
+            ResourceWarning: Enable tracemalloc to get the object allocation traceback
+        ''').strip()
+        self.assertEqual(stderr, expected)
+
+        # tracemalloc enabled
+        stderr = run('-Wd', '-X', 'tracemalloc=2', os_helper.TESTFN)
+        expected = textwrap.dedent(f'''
+            {filename}:5: ResourceWarning: unclosed file <...>
+              f = None
+            Object allocated at (most recent call last):
+              File "{filename}", lineno 7
+                func()
+              File "{filename}", lineno 3
+                f = open(__file__, "rb")
+        ''').strip()
+        self.assertEqual(stderr, expected)
+
+
+class CatchWarningTests(BaseTest):
+
+    """Test catch_warnings()."""
+
+    def test_catch_warnings_restore(self):
+        wmod = self.module
+        orig_filters = wmod.filters
+        orig_showwarning = wmod.showwarning
+        # Ensure both showwarning and filters are restored when recording
+        with wmod.catch_warnings(module=wmod, record=True):
+            wmod.filters = wmod.showwarning = object()
+        self.assertIs(wmod.filters, orig_filters)
+        self.assertIs(wmod.showwarning, orig_showwarning)
+        # Same test, but with recording disabled
+        with wmod.catch_warnings(module=wmod, record=False):
+            wmod.filters = wmod.showwarning = object()
+        self.assertIs(wmod.filters, orig_filters)
+        self.assertIs(wmod.showwarning, orig_showwarning)
+
+    def test_catch_warnings_recording(self):
+        wmod = self.module
+        # Ensure warnings are recorded when requested
+        with wmod.catch_warnings(module=wmod, record=True) as w:
+            self.assertEqual(w, [])
+            self.assertIs(type(w), list)
+            wmod.simplefilter("always")
+            wmod.warn("foo")
+            self.assertEqual(str(w[-1].message), "foo")
+            wmod.warn("bar")
+            self.assertEqual(str(w[-1].message), "bar")
+            self.assertEqual(str(w[0].message), "foo")
+            self.assertEqual(str(w[1].message), "bar")
+            del w[:]
+            self.assertEqual(w, [])
+        # Ensure warnings are not recorded when not requested
+        orig_showwarning = wmod.showwarning
+        with wmod.catch_warnings(module=wmod, record=False) as w:
+            self.assertIsNone(w)
+            self.assertIs(wmod.showwarning, orig_showwarning)
+
+    def test_catch_warnings_reentry_guard(self):
+        wmod = self.module
+        # Ensure catch_warnings is protected against incorrect usage
+        x = wmod.catch_warnings(module=wmod, record=True)
+        self.assertRaises(RuntimeError, x.__exit__)
+        with x:
+            self.assertRaises(RuntimeError, x.__enter__)
+        # Same test, but with recording disabled
+        x = wmod.catch_warnings(module=wmod, record=False)
+        self.assertRaises(RuntimeError, x.__exit__)
+        with x:
+            self.assertRaises(RuntimeError, x.__enter__)
+
+    def test_catch_warnings_defaults(self):
+        wmod = self.module
+        orig_filters = wmod.filters
+        orig_showwarning = wmod.showwarning
+        # Ensure default behaviour is not to record warnings
+        with wmod.catch_warnings(module=wmod) as w:
+            self.assertIsNone(w)
+            self.assertIs(wmod.showwarning, orig_showwarning)
+            self.assertIsNot(wmod.filters, orig_filters)
+        self.assertIs(wmod.filters, orig_filters)
+        if wmod is sys.modules['warnings']:
+            # Ensure the default module is this one
+            with wmod.catch_warnings() as w:
+                self.assertIsNone(w)
+                self.assertIs(wmod.showwarning, orig_showwarning)
+                self.assertIsNot(wmod.filters, orig_filters)
+            self.assertIs(wmod.filters, orig_filters)
+
+    def test_record_override_showwarning_before(self):
+        # Issue #28835: If warnings.showwarning() was overridden, make sure
+        # that catch_warnings(record=True) overrides it again.
+        text = "This is a warning"
+        wmod = self.module
+        my_log = []
+
+        def my_logger(message, category, filename, lineno, file=None, line=None):
+            nonlocal my_log
+            my_log.append(message)
+
+        # Override warnings.showwarning() before calling catch_warnings()
+        with support.swap_attr(wmod, 'showwarning', my_logger):
+            with wmod.catch_warnings(module=wmod, record=True) as log:
+                self.assertIsNot(wmod.showwarning, my_logger)
+
+                wmod.simplefilter("always")
+                wmod.warn(text)
+
+            self.assertIs(wmod.showwarning, my_logger)
+
+        self.assertEqual(len(log), 1, log)
+        self.assertEqual(log[0].message.args[0], text)
+        self.assertEqual(my_log, [])
+
+    def test_record_override_showwarning_inside(self):
+        # Issue #28835: It is possible to override warnings.showwarning()
+        # in the catch_warnings(record=True) context manager.
+        text = "This is a warning"
+        wmod = self.module
+        my_log = []
+
+        def my_logger(message, category, filename, lineno, file=None, line=None):
+            nonlocal my_log
+            my_log.append(message)
+
+        with wmod.catch_warnings(module=wmod, record=True) as log:
+            wmod.simplefilter("always")
+            wmod.showwarning = my_logger
+            wmod.warn(text)
+
+        self.assertEqual(len(my_log), 1, my_log)
+        self.assertEqual(my_log[0].args[0], text)
+        self.assertEqual(log, [])
+
+    def test_check_warnings(self):
+        # Explicit tests for the test.support convenience wrapper
+        wmod = self.module
+        if wmod is not sys.modules['warnings']:
+            self.skipTest('module to test is not loaded warnings module')
+        with warnings_helper.check_warnings(quiet=False) as w:
+            self.assertEqual(w.warnings, [])
+            wmod.simplefilter("always")
+            wmod.warn("foo")
+            self.assertEqual(str(w.message), "foo")
+            wmod.warn("bar")
+            self.assertEqual(str(w.message), "bar")
+            self.assertEqual(str(w.warnings[0].message), "foo")
+            self.assertEqual(str(w.warnings[1].message), "bar")
+            w.reset()
+            self.assertEqual(w.warnings, [])
+
+        with warnings_helper.check_warnings():
+            # defaults to quiet=True without argument
+            pass
+        with warnings_helper.check_warnings(('foo', UserWarning)):
+            wmod.warn("foo")
+
+        with self.assertRaises(AssertionError):
+            with warnings_helper.check_warnings(('', RuntimeWarning)):
+                # defaults to quiet=False with argument
+                pass
+        with self.assertRaises(AssertionError):
+            with warnings_helper.check_warnings(('foo', RuntimeWarning)):
+                wmod.warn("foo")
+
+class CCatchWarningTests(CatchWarningTests, unittest.TestCase):
+    module = c_warnings
+
+class PyCatchWarningTests(CatchWarningTests, unittest.TestCase):
+    module = py_warnings
+
+
+class EnvironmentVariableTests(BaseTest):
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_single_warning(self):
+        rc, stdout, stderr = assert_python_ok("-c",
+            "import sys; sys.stdout.write(str(sys.warnoptions))",
+            PYTHONWARNINGS="ignore::DeprecationWarning",
+            PYTHONDEVMODE="")
+        self.assertEqual(stdout, b"['ignore::DeprecationWarning']")
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_comma_separated_warnings(self):
+        rc, stdout, stderr = assert_python_ok("-c",
+            "import sys; sys.stdout.write(str(sys.warnoptions))",
+            PYTHONWARNINGS="ignore::DeprecationWarning,ignore::UnicodeWarning",
+            PYTHONDEVMODE="")
+        self.assertEqual(stdout,
+            b"['ignore::DeprecationWarning', 'ignore::UnicodeWarning']")
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    @force_not_colorized
+    def test_envvar_and_command_line(self):
+        rc, stdout, stderr = assert_python_ok("-Wignore::UnicodeWarning", "-c",
+            "import sys; sys.stdout.write(str(sys.warnoptions))",
+            PYTHONWARNINGS="ignore::DeprecationWarning",
+            PYTHONDEVMODE="")
+        self.assertEqual(stdout,
+            b"['ignore::DeprecationWarning', 'ignore::UnicodeWarning']")
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    @force_not_colorized
+    def test_conflicting_envvar_and_command_line(self):
+        rc, stdout, stderr = assert_python_failure("-Werror::DeprecationWarning", "-c",
+            "import sys, warnings; sys.stdout.write(str(sys.warnoptions)); "
+            "warnings.warn('Message', DeprecationWarning)",
+            PYTHONWARNINGS="default::DeprecationWarning",
+            PYTHONDEVMODE="")
+        self.assertEqual(stdout,
+            b"['default::DeprecationWarning', 'error::DeprecationWarning']")
+        self.assertEqual(stderr.splitlines(),
+            [b"Traceback (most recent call last):",
+             b"  File \"<string>\", line 1, in <module>",
+             b'    import sys, warnings; sys.stdout.write(str(sys.warnoptions)); warnings.w'
+             b"arn('Message', DeprecationWarning)",
+             b'                                                                  ~~~~~~~~~~'
+             b'~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^',
+             b"DeprecationWarning: Message"])
+
+    def test_default_filter_configuration(self):
+        pure_python_api = self.module is py_warnings
+        if support.Py_DEBUG:
+            expected_default_filters = []
+        else:
+            if pure_python_api:
+                main_module_filter = re.compile("__main__")
+            else:
+                main_module_filter = "__main__"
+            expected_default_filters = [
+                ('default', None, DeprecationWarning, main_module_filter, 0),
+                ('ignore', None, DeprecationWarning, None, 0),
+                ('ignore', None, PendingDeprecationWarning, None, 0),
+                ('ignore', None, ImportWarning, None, 0),
+                ('ignore', None, ResourceWarning, None, 0),
+            ]
+        expected_output = [str(f).encode() for f in expected_default_filters]
+
+        if pure_python_api:
+            # Disable the warnings acceleration module in the subprocess
+            code = "import sys; sys.modules.pop('warnings', None); sys.modules['_warnings'] = None; "
+        else:
+            code = ""
+        code += "import warnings; [print(f) for f in warnings.filters]"
+
+        rc, stdout, stderr = assert_python_ok("-c", code, __isolated=True)
+        stdout_lines = [line.strip() for line in stdout.splitlines()]
+        self.maxDiff = None
+        self.assertEqual(stdout_lines, expected_output)
+
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    @unittest.skipUnless(sys.getfilesystemencoding() != 'ascii',
+                         'requires non-ascii filesystemencoding')
+    def test_nonascii(self):
+        PYTHONWARNINGS="ignore:DeprecationWarning" + os_helper.FS_NONASCII
+        rc, stdout, stderr = assert_python_ok("-c",
+            "import sys; sys.stdout.write(str(sys.warnoptions))",
+            PYTHONIOENCODING="utf-8",
+            PYTHONWARNINGS=PYTHONWARNINGS,
+            PYTHONDEVMODE="")
+        self.assertEqual(stdout, str([PYTHONWARNINGS]).encode())
+
+class CEnvironmentVariableTests(EnvironmentVariableTests, unittest.TestCase):
+    module = c_warnings
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_default_filter_configuration(self):
+        # XXX: RUSTPYHTON; remove the entire function when fixed
+        super().test_default_filter_configuration()
+
+
+class PyEnvironmentVariableTests(EnvironmentVariableTests, unittest.TestCase):
+    module = py_warnings
+
+
+class _DeprecatedTest(BaseTest, unittest.TestCase):
+
+    """Test _deprecated()."""
+
+    module = original_warnings
+
+    def test_warning(self):
+        version = (3, 11, 0, "final", 0)
+        test = [(4, 12), (4, 11), (4, 0), (3, 12)]
+        for remove in test:
+            msg = rf".*test_warnings.*{remove[0]}\.{remove[1]}"
+            filter = msg, DeprecationWarning
+            with self.subTest(remove=remove):
+                with warnings_helper.check_warnings(filter, quiet=False):
+                    self.module._deprecated("test_warnings", remove=remove,
+                                            _version=version)
+
+        version = (3, 11, 0, "alpha", 0)
+        msg = r".*test_warnings.*3\.11"
+        with warnings_helper.check_warnings((msg, DeprecationWarning), quiet=False):
+            self.module._deprecated("test_warnings", remove=(3, 11),
+                                    _version=version)
+
+    def test_RuntimeError(self):
+        version = (3, 11, 0, "final", 0)
+        test = [(2, 0), (2, 12), (3, 10)]
+        for remove in test:
+            with self.subTest(remove=remove):
+                with self.assertRaises(RuntimeError):
+                    self.module._deprecated("test_warnings", remove=remove,
+                                            _version=version)
+        for level in ["beta", "candidate", "final"]:
+            version = (3, 11, 0, level, 0)
+            with self.subTest(releaselevel=level):
+                with self.assertRaises(RuntimeError):
+                    self.module._deprecated("test_warnings", remove=(3, 11),
+                                            _version=version)
+
+
+class BootstrapTest(unittest.TestCase):
+
+    def test_issue_8766(self):
+        # "import encodings" emits a warning whereas the warnings is not loaded
+        # or not completely loaded (warnings imports indirectly encodings by
+        # importing linecache) yet
+        with os_helper.temp_cwd() as cwd, os_helper.temp_cwd('encodings'):
+            # encodings loaded by initfsencoding()
+            assert_python_ok('-c', 'pass', PYTHONPATH=cwd)
+
+            # Use -W to load warnings module at startup
+            assert_python_ok('-c', 'pass', '-W', 'always', PYTHONPATH=cwd)
+
+
+class FinalizationTest(unittest.TestCase):
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_finalization(self):
+        # Issue #19421: warnings.warn() should not crash
+        # during Python finalization
+        code = """
+import warnings
+warn = warnings.warn
+
+class A:
+    def __del__(self):
+        warn("test")
+
+a=A()
+        """
+        rc, out, err = assert_python_ok("-c", code)
+        self.assertEqual(err.decode().rstrip(),
+                         '<string>:7: UserWarning: test')
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_late_resource_warning(self):
+        # Issue #21925: Emitting a ResourceWarning late during the Python
+        # shutdown must be logged.
+
+        expected = b"<sys>:0: ResourceWarning: unclosed file "
+
+        # don't import the warnings module
+        # (_warnings will try to import it)
+        code = "f = open(%a)" % __file__
+        rc, out, err = assert_python_ok("-Wd", "-c", code)
+        self.assertTrue(err.startswith(expected), ascii(err))
+
+        # import the warnings module
+        code = "import warnings; f = open(%a)" % __file__
+        rc, out, err = assert_python_ok("-Wd", "-c", code)
+        self.assertTrue(err.startswith(expected), ascii(err))
+
+
+class DeprecatedTests(unittest.TestCase):
+    def test_dunder_deprecated(self):
+        @deprecated("A will go away soon")
+        class A:
+            pass
+
+        self.assertEqual(A.__deprecated__, "A will go away soon")
+        self.assertIsInstance(A, type)
+
+        @deprecated("b will go away soon")
+        def b():
+            pass
+
+        self.assertEqual(b.__deprecated__, "b will go away soon")
+        self.assertIsInstance(b, types.FunctionType)
+
+        @overload
+        @deprecated("no more ints")
+        def h(x: int) -> int: ...
+        @overload
+        def h(x: str) -> str: ...
+        def h(x):
+            return x
+
+        overloads = get_overloads(h)
+        self.assertEqual(len(overloads), 2)
+        self.assertEqual(overloads[0].__deprecated__, "no more ints")
+
+    def test_class(self):
+        @deprecated("A will go away soon")
+        class A:
+            pass
+
+        with self.assertWarnsRegex(DeprecationWarning, "A will go away soon"):
+            A()
+        with self.assertWarnsRegex(DeprecationWarning, "A will go away soon"):
+            with self.assertRaises(TypeError):
+                A(42)
+
+    def test_class_with_init(self):
+        @deprecated("HasInit will go away soon")
+        class HasInit:
+            def __init__(self, x):
+                self.x = x
+
+        with self.assertWarnsRegex(DeprecationWarning, "HasInit will go away soon"):
+            instance = HasInit(42)
+        self.assertEqual(instance.x, 42)
+
+    def test_class_with_new(self):
+        has_new_called = False
+
+        @deprecated("HasNew will go away soon")
+        class HasNew:
+            def __new__(cls, x):
+                nonlocal has_new_called
+                has_new_called = True
+                return super().__new__(cls)
+
+            def __init__(self, x) -> None:
+                self.x = x
+
+        with self.assertWarnsRegex(DeprecationWarning, "HasNew will go away soon"):
+            instance = HasNew(42)
+        self.assertEqual(instance.x, 42)
+        self.assertTrue(has_new_called)
+
+    def test_class_with_inherited_new(self):
+        new_base_called = False
+
+        class NewBase:
+            def __new__(cls, x):
+                nonlocal new_base_called
+                new_base_called = True
+                return super().__new__(cls)
+
+            def __init__(self, x) -> None:
+                self.x = x
+
+        @deprecated("HasInheritedNew will go away soon")
+        class HasInheritedNew(NewBase):
+            pass
+
+        with self.assertWarnsRegex(DeprecationWarning, "HasInheritedNew will go away soon"):
+            instance = HasInheritedNew(42)
+        self.assertEqual(instance.x, 42)
+        self.assertTrue(new_base_called)
+
+    def test_class_with_new_but_no_init(self):
+        new_called = False
+
+        @deprecated("HasNewNoInit will go away soon")
+        class HasNewNoInit:
+            def __new__(cls, x):
+                nonlocal new_called
+                new_called = True
+                obj = super().__new__(cls)
+                obj.x = x
+                return obj
+
+        with self.assertWarnsRegex(DeprecationWarning, "HasNewNoInit will go away soon"):
+            instance = HasNewNoInit(42)
+        self.assertEqual(instance.x, 42)
+        self.assertTrue(new_called)
+
+    def test_mixin_class(self):
+        @deprecated("Mixin will go away soon")
+        class Mixin:
+            pass
+
+        class Base:
+            def __init__(self, a) -> None:
+                self.a = a
+
+        with self.assertWarnsRegex(DeprecationWarning, "Mixin will go away soon"):
+            class Child(Base, Mixin):
+                pass
+
+        instance = Child(42)
+        self.assertEqual(instance.a, 42)
+
+    def test_do_not_shadow_user_arguments(self):
+        new_called = False
+        new_called_cls = None
+
+        @deprecated("MyMeta will go away soon")
+        class MyMeta(type):
+            def __new__(mcs, name, bases, attrs, cls=None):
+                nonlocal new_called, new_called_cls
+                new_called = True
+                new_called_cls = cls
+                return super().__new__(mcs, name, bases, attrs)
+
+        with self.assertWarnsRegex(DeprecationWarning, "MyMeta will go away soon"):
+            class Foo(metaclass=MyMeta, cls='haha'):
+                pass
+
+        self.assertTrue(new_called)
+        self.assertEqual(new_called_cls, 'haha')
+
+    def test_existing_init_subclass(self):
+        @deprecated("C will go away soon")
+        class C:
+            def __init_subclass__(cls) -> None:
+                cls.inited = True
+
+        with self.assertWarnsRegex(DeprecationWarning, "C will go away soon"):
+            C()
+
+        with self.assertWarnsRegex(DeprecationWarning, "C will go away soon"):
+            class D(C):
+                pass
+
+        self.assertTrue(D.inited)
+        self.assertIsInstance(D(), D)  # no deprecation
+
+    def test_existing_init_subclass_in_base(self):
+        class Base:
+            def __init_subclass__(cls, x) -> None:
+                cls.inited = x
+
+        @deprecated("C will go away soon")
+        class C(Base, x=42):
+            pass
+
+        self.assertEqual(C.inited, 42)
+
+        with self.assertWarnsRegex(DeprecationWarning, "C will go away soon"):
+            C()
+
+        with self.assertWarnsRegex(DeprecationWarning, "C will go away soon"):
+            class D(C, x=3):
+                pass
+
+        self.assertEqual(D.inited, 3)
+
+    def test_init_subclass_has_correct_cls(self):
+        init_subclass_saw = None
+
+        @deprecated("Base will go away soon")
+        class Base:
+            def __init_subclass__(cls) -> None:
+                nonlocal init_subclass_saw
+                init_subclass_saw = cls
+
+        self.assertIsNone(init_subclass_saw)
+
+        with self.assertWarnsRegex(DeprecationWarning, "Base will go away soon"):
+            class C(Base):
+                pass
+
+        self.assertIs(init_subclass_saw, C)
+
+    def test_init_subclass_with_explicit_classmethod(self):
+        init_subclass_saw = None
+
+        @deprecated("Base will go away soon")
+        class Base:
+            @classmethod
+            def __init_subclass__(cls) -> None:
+                nonlocal init_subclass_saw
+                init_subclass_saw = cls
+
+        self.assertIsNone(init_subclass_saw)
+
+        with self.assertWarnsRegex(DeprecationWarning, "Base will go away soon"):
+            class C(Base):
+                pass
+
+        self.assertIs(init_subclass_saw, C)
+
+    def test_function(self):
+        @deprecated("b will go away soon")
+        def b():
+            pass
+
+        with self.assertWarnsRegex(DeprecationWarning, "b will go away soon"):
+            b()
+
+    def test_method(self):
+        class Capybara:
+            @deprecated("x will go away soon")
+            def x(self):
+                pass
+
+        instance = Capybara()
+        with self.assertWarnsRegex(DeprecationWarning, "x will go away soon"):
+            instance.x()
+
+    def test_property(self):
+        class Capybara:
+            @property
+            @deprecated("x will go away soon")
+            def x(self):
+                pass
+
+            @property
+            def no_more_setting(self):
+                return 42
+
+            @no_more_setting.setter
+            @deprecated("no more setting")
+            def no_more_setting(self, value):
+                pass
+
+        instance = Capybara()
+        with self.assertWarnsRegex(DeprecationWarning, "x will go away soon"):
+            instance.x
+
+        with py_warnings.catch_warnings():
+            py_warnings.simplefilter("error")
+            self.assertEqual(instance.no_more_setting, 42)
+
+        with self.assertWarnsRegex(DeprecationWarning, "no more setting"):
+            instance.no_more_setting = 42
+
+    def test_category(self):
+        @deprecated("c will go away soon", category=RuntimeWarning)
+        def c():
+            pass
+
+        with self.assertWarnsRegex(RuntimeWarning, "c will go away soon"):
+            c()
+
+    def test_turn_off_warnings(self):
+        @deprecated("d will go away soon", category=None)
+        def d():
+            pass
+
+        with py_warnings.catch_warnings():
+            py_warnings.simplefilter("error")
+            d()
+
+    def test_only_strings_allowed(self):
+        with self.assertRaisesRegex(
+            TypeError,
+            "Expected an object of type str for 'message', not 'type'"
+        ):
+            @deprecated
+            class Foo: ...
+
+        with self.assertRaisesRegex(
+            TypeError,
+            "Expected an object of type str for 'message', not 'function'"
+        ):
+            @deprecated
+            def foo(): ...
+
+    def test_no_retained_references_to_wrapper_instance(self):
+        @deprecated('depr')
+        def d(): pass
+
+        self.assertFalse(any(
+            isinstance(cell.cell_contents, deprecated) for cell in d.__closure__
+        ))
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_inspect(self):
+        @deprecated("depr")
+        def sync():
+            pass
+
+        @deprecated("depr")
+        async def coro():
+            pass
+
+        class Cls:
+            @deprecated("depr")
+            def sync(self):
+                pass
+
+            @deprecated("depr")
+            async def coro(self):
+                pass
+
+        self.assertFalse(inspect.iscoroutinefunction(sync))
+        self.assertTrue(inspect.iscoroutinefunction(coro))
+        self.assertFalse(inspect.iscoroutinefunction(Cls.sync))
+        self.assertTrue(inspect.iscoroutinefunction(Cls.coro))
+
+    # TODO: RUSTPYTHON
+    @unittest.expectedFailure
+    def test_inspect_class_signature(self):
+        class Cls1:  # no __init__ or __new__
+            pass
+
+        class Cls2:  # __new__ only
+            def __new__(cls, x, y):
+                return super().__new__(cls)
+
+        class Cls3:  # __init__ only
+            def __init__(self, x, y):
+                pass
+
+        class Cls4:  # __new__ and __init__
+            def __new__(cls, x, y):
+                return super().__new__(cls)
+
+            def __init__(self, x, y):
+                pass
+
+        class Cls5(Cls1):  # inherits no __init__ or __new__
+            pass
+
+        class Cls6(Cls2):  # inherits __new__ only
+            pass
+
+        class Cls7(Cls3):  # inherits __init__ only
+            pass
+
+        class Cls8(Cls4):  # inherits __new__ and __init__
+            pass
+
+        # The `@deprecated` decorator will update the class in-place.
+        # Test the child classes first.
+        for cls in reversed((Cls1, Cls2, Cls3, Cls4, Cls5, Cls6, Cls7, Cls8)):
+            with self.subTest(f'class {cls.__name__} signature'):
+                try:
+                    original_signature = inspect.signature(cls)
+                except ValueError:
+                    original_signature = None
+                try:
+                    original_new_signature = inspect.signature(cls.__new__)
+                except ValueError:
+                    original_new_signature = None
+
+                deprecated_cls = deprecated("depr")(cls)
+
+                try:
+                    deprecated_signature = inspect.signature(deprecated_cls)
+                except ValueError:
+                    deprecated_signature = None
+                self.assertEqual(original_signature, deprecated_signature)
+
+                try:
+                    deprecated_new_signature = inspect.signature(deprecated_cls.__new__)
+                except ValueError:
+                    deprecated_new_signature = None
+                self.assertEqual(original_new_signature, deprecated_new_signature)
+
+
+def setUpModule():
+    py_warnings.onceregistry.clear()
+    c_warnings.onceregistry.clear()
+
+
+tearDownModule = setUpModule
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Lib/test/test_warnings/__main__.py b/Lib/test/test_warnings/__main__.py
new file mode 100644
index 0000000000..44e52ec070
--- /dev/null
+++ b/Lib/test/test_warnings/__main__.py
@@ -0,0 +1,3 @@
+import unittest
+
+unittest.main('test.test_warnings')
diff --git a/Lib/test/test_warnings/data/import_warning.py b/Lib/test/test_warnings/data/import_warning.py
new file mode 100644
index 0000000000..32daec1140
--- /dev/null
+++ b/Lib/test/test_warnings/data/import_warning.py
@@ -0,0 +1,3 @@
+import warnings
+
+warnings.warn('module-level warning', DeprecationWarning, stacklevel=2)
diff --git a/Lib/test/test_warnings/data/package_helper.py b/Lib/test/test_warnings/data/package_helper.py
new file mode 100644
index 0000000000..c22a4f6405
--- /dev/null
+++ b/Lib/test/test_warnings/data/package_helper.py
@@ -0,0 +1,10 @@
+# helper to the helper for testing skip_file_prefixes.
+
+import os
+
+package_path = os.path.dirname(__file__)
+
+def inner_api(message, *, stacklevel, warnings_module):
+    warnings_module.warn(
+            message, stacklevel=stacklevel,
+            skip_file_prefixes=(package_path,))
diff --git a/Lib/test/test_warnings/data/stacklevel.py b/Lib/test/test_warnings/data/stacklevel.py
new file mode 100644
index 0000000000..c6dd24733b
--- /dev/null
+++ b/Lib/test/test_warnings/data/stacklevel.py
@@ -0,0 +1,15 @@
+# Helper module for testing stacklevel and skip_file_prefixes arguments
+# of warnings.warn()
+
+import warnings
+from test.test_warnings.data import package_helper
+
+def outer(message, stacklevel=1):
+    inner(message, stacklevel)
+
+def inner(message, stacklevel=1):
+    warnings.warn(message, stacklevel=stacklevel)
+
+def package(message, *, stacklevel):
+    package_helper.inner_api(message, stacklevel=stacklevel,
+                             warnings_module=warnings)
diff --git a/Lib/warnings.py b/Lib/warnings.py
index 7d8c440012..f83aaf231e 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -5,7 +5,7 @@
 
 __all__ = ["warn", "warn_explicit", "showwarning",
            "formatwarning", "filterwarnings", "simplefilter",
-           "resetwarnings", "catch_warnings"]
+           "resetwarnings", "catch_warnings", "deprecated"]
 
 def showwarning(message, category, filename, lineno, file=None, line=None):
     """Hook to write a warning to a file; replace if you like."""
@@ -58,15 +58,16 @@ def _formatwarnmsg_impl(msg):
         # catch Exception, not only ImportError and RecursionError.
         except Exception:
             # don't suggest to enable tracemalloc if it's not available
-            tracing = True
+            suggest_tracemalloc = False
             tb = None
         else:
-            tracing = tracemalloc.is_tracing()
             try:
+                suggest_tracemalloc = not tracemalloc.is_tracing()
                 tb = tracemalloc.get_object_traceback(msg.source)
             except Exception:
                 # When a warning is logged during Python shutdown, tracemalloc
                 # and the import machinery don't work anymore
+                suggest_tracemalloc = False
                 tb = None
 
         if tb is not None:
@@ -85,7 +86,7 @@ def _formatwarnmsg_impl(msg):
                 if line:
                     line = line.strip()
                     s += '    %s\n' % line
-        elif not tracing:
+        elif suggest_tracemalloc:
             s += (f'{category}: Enable tracemalloc to get the object '
                   f'allocation traceback\n')
     return s
@@ -139,14 +140,18 @@ def filterwarnings(action, message="", category=Warning, module="", lineno=0,
     'lineno' -- an integer line number, 0 matches all warnings
     'append' -- if true, append to the list of filters
     """
-    assert action in ("error", "ignore", "always", "default", "module",
-                      "once"), "invalid action: %r" % (action,)
-    assert isinstance(message, str), "message must be a string"
-    assert isinstance(category, type), "category must be a class"
-    assert issubclass(category, Warning), "category must be a Warning subclass"
-    assert isinstance(module, str), "module must be a string"
-    assert isinstance(lineno, int) and lineno >= 0, \
-           "lineno must be an int >= 0"
+    if action not in {"error", "ignore", "always", "default", "module", "once"}:
+        raise ValueError(f"invalid action: {action!r}")
+    if not isinstance(message, str):
+        raise TypeError("message must be a string")
+    if not isinstance(category, type) or not issubclass(category, Warning):
+        raise TypeError("category must be a Warning subclass")
+    if not isinstance(module, str):
+        raise TypeError("module must be a string")
+    if not isinstance(lineno, int):
+        raise TypeError("lineno must be an int")
+    if lineno < 0:
+        raise ValueError("lineno must be an int >= 0")
 
     if message or module:
         import re
@@ -172,10 +177,12 @@ def simplefilter(action, category=Warning, lineno=0, append=False):
     'lineno' -- an integer line number, 0 matches all warnings
     'append' -- if true, append to the list of filters
     """
-    assert action in ("error", "ignore", "always", "default", "module",
-                      "once"), "invalid action: %r" % (action,)
-    assert isinstance(lineno, int) and lineno >= 0, \
-           "lineno must be an int >= 0"
+    if action not in {"error", "ignore", "always", "default", "module", "once"}:
+        raise ValueError(f"invalid action: {action!r}")
+    if not isinstance(lineno, int):
+        raise TypeError("lineno must be an int")
+    if lineno < 0:
+        raise ValueError("lineno must be an int >= 0")
     _add_filter(action, None, category, None, lineno, append=append)
 
 def _add_filter(*item, append):
@@ -269,22 +276,32 @@ def _getcategory(category):
     return cat
 
 
+def _is_internal_filename(filename):
+    return 'importlib' in filename and '_bootstrap' in filename
+
+
+def _is_filename_to_skip(filename, skip_file_prefixes):
+    return any(filename.startswith(prefix) for prefix in skip_file_prefixes)
+
+
 def _is_internal_frame(frame):
     """Signal whether the frame is an internal CPython implementation detail."""
-    filename = frame.f_code.co_filename
-    return 'importlib' in filename and '_bootstrap' in filename
+    return _is_internal_filename(frame.f_code.co_filename)
 
 
-def _next_external_frame(frame):
-    """Find the next frame that doesn't involve CPython internals."""
+def _next_external_frame(frame, skip_file_prefixes):
+    """Find the next frame that doesn't involve Python or user internals."""
     frame = frame.f_back
-    while frame is not None and _is_internal_frame(frame):
+    while frame is not None and (
+            _is_internal_filename(filename := frame.f_code.co_filename) or
+            _is_filename_to_skip(filename, skip_file_prefixes)):
         frame = frame.f_back
     return frame
 
 
 # Code typically replaced by _warnings
-def warn(message, category=None, stacklevel=1, source=None):
+def warn(message, category=None, stacklevel=1, source=None,
+         *, skip_file_prefixes=()):
     """Issue a warning, or maybe ignore it or raise an exception."""
     # Check if message is already a Warning object
     if isinstance(message, Warning):
@@ -295,6 +312,11 @@ def warn(message, category=None, stacklevel=1, source=None):
     if not (isinstance(category, type) and issubclass(category, Warning)):
         raise TypeError("category must be a Warning subclass, "
                         "not '{:s}'".format(type(category).__name__))
+    if not isinstance(skip_file_prefixes, tuple):
+        # The C version demands a tuple for implementation performance.
+        raise TypeError('skip_file_prefixes must be a tuple of strs.')
+    if skip_file_prefixes:
+        stacklevel = max(2, stacklevel)
     # Get context information
     try:
         if stacklevel <= 1 or _is_internal_frame(sys._getframe(1)):
@@ -305,13 +327,13 @@ def warn(message, category=None, stacklevel=1, source=None):
             frame = sys._getframe(1)
             # Look for one frame less since the above line starts us off.
             for x in range(stacklevel-1):
-                frame = _next_external_frame(frame)
+                frame = _next_external_frame(frame, skip_file_prefixes)
                 if frame is None:
                     raise ValueError
     except ValueError:
         globals = sys.__dict__
-        filename = "sys"
-        lineno = 1
+        filename = "<sys>"
+        lineno = 0
     else:
         globals = frame.f_globals
         filename = frame.f_code.co_filename
@@ -391,7 +413,7 @@ def warn_explicit(message, category, filename, lineno,
               "Unrecognized action (%r) in warnings.filters:\n %s" %
               (action, item))
     # Print message and context
-    msg = WarningMessage(message, category, filename, lineno, source)
+    msg = WarningMessage(message, category, filename, lineno, source=source)
     _showwarnmsg(msg)
 
 
@@ -493,6 +515,139 @@ def __exit__(self, *exc_info):
         self._module._showwarnmsg_impl = self._showwarnmsg_impl
 
 
+class deprecated:
+    """Indicate that a class, function or overload is deprecated.
+
+    When this decorator is applied to an object, the type checker
+    will generate a diagnostic on usage of the deprecated object.
+
+    Usage:
+
+        @deprecated("Use B instead")
+        class A:
+            pass
+
+        @deprecated("Use g instead")
+        def f():
+            pass
+
+        @overload
+        @deprecated("int support is deprecated")
+        def g(x: int) -> int: ...
+        @overload
+        def g(x: str) -> int: ...
+
+    The warning specified by *category* will be emitted at runtime
+    on use of deprecated objects. For functions, that happens on calls;
+    for classes, on instantiation and on creation of subclasses.
+    If the *category* is ``None``, no warning is emitted at runtime.
+    The *stacklevel* determines where the
+    warning is emitted. If it is ``1`` (the default), the warning
+    is emitted at the direct caller of the deprecated object; if it
+    is higher, it is emitted further up the stack.
+    Static type checker behavior is not affected by the *category*
+    and *stacklevel* arguments.
+
+    The deprecation message passed to the decorator is saved in the
+    ``__deprecated__`` attribute on the decorated object.
+    If applied to an overload, the decorator
+    must be after the ``@overload`` decorator for the attribute to
+    exist on the overload as returned by ``get_overloads()``.
+
+    See PEP 702 for details.
+
+    """
+    def __init__(
+        self,
+        message: str,
+        /,
+        *,
+        category: type[Warning] | None = DeprecationWarning,
+        stacklevel: int = 1,
+    ) -> None:
+        if not isinstance(message, str):
+            raise TypeError(
+                f"Expected an object of type str for 'message', not {type(message).__name__!r}"
+            )
+        self.message = message
+        self.category = category
+        self.stacklevel = stacklevel
+
+    def __call__(self, arg, /):
+        # Make sure the inner functions created below don't
+        # retain a reference to self.
+        msg = self.message
+        category = self.category
+        stacklevel = self.stacklevel
+        if category is None:
+            arg.__deprecated__ = msg
+            return arg
+        elif isinstance(arg, type):
+            import functools
+            from types import MethodType
+
+            original_new = arg.__new__
+
+            @functools.wraps(original_new)
+            def __new__(cls, /, *args, **kwargs):
+                if cls is arg:
+                    warn(msg, category=category, stacklevel=stacklevel + 1)
+                if original_new is not object.__new__:
+                    return original_new(cls, *args, **kwargs)
+                # Mirrors a similar check in object.__new__.
+                elif cls.__init__ is object.__init__ and (args or kwargs):
+                    raise TypeError(f"{cls.__name__}() takes no arguments")
+                else:
+                    return original_new(cls)
+
+            arg.__new__ = staticmethod(__new__)
+
+            original_init_subclass = arg.__init_subclass__
+            # We need slightly different behavior if __init_subclass__
+            # is a bound method (likely if it was implemented in Python)
+            if isinstance(original_init_subclass, MethodType):
+                original_init_subclass = original_init_subclass.__func__
+
+                @functools.wraps(original_init_subclass)
+                def __init_subclass__(*args, **kwargs):
+                    warn(msg, category=category, stacklevel=stacklevel + 1)
+                    return original_init_subclass(*args, **kwargs)
+
+                arg.__init_subclass__ = classmethod(__init_subclass__)
+            # Or otherwise, which likely means it's a builtin such as
+            # object's implementation of __init_subclass__.
+            else:
+                @functools.wraps(original_init_subclass)
+                def __init_subclass__(*args, **kwargs):
+                    warn(msg, category=category, stacklevel=stacklevel + 1)
+                    return original_init_subclass(*args, **kwargs)
+
+                arg.__init_subclass__ = __init_subclass__
+
+            arg.__deprecated__ = __new__.__deprecated__ = msg
+            __init_subclass__.__deprecated__ = msg
+            return arg
+        elif callable(arg):
+            import functools
+            import inspect
+
+            @functools.wraps(arg)
+            def wrapper(*args, **kwargs):
+                warn(msg, category=category, stacklevel=stacklevel + 1)
+                return arg(*args, **kwargs)
+
+            if inspect.iscoroutinefunction(arg):
+                wrapper = inspect.markcoroutinefunction(wrapper)
+
+            arg.__deprecated__ = wrapper.__deprecated__ = msg
+            return wrapper
+        else:
+            raise TypeError(
+                "@deprecated decorator with non-None category must be applied to "
+                f"a class or callable, not {arg!r}"
+            )
+
+
 _DEPRECATED_MSG = "{name!r} is deprecated and slated for removal in Python {remove}"
 
 def _deprecated(name, message=_DEPRECATED_MSG, *, remove, _version=sys.version_info):
@@ -502,7 +657,7 @@ def _deprecated(name, message=_DEPRECATED_MSG, *, remove, _version=sys.version_i
     the current Python version or the same version but past the alpha.
 
     The *message* argument is formatted with *name* and *remove* as a Python
-    version (e.g. "3.11").
+    version tuple (e.g. (3, 11)).
 
     """
     remove_formatted = f"{remove[0]}.{remove[1]}"