Merge from 3.5

4 files changed, 976 insertions, 0 deletions

diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py
new file mode 100644
index 0000000..cea9c57
--- /dev/null
+++ b/Lib/test/test_warnings/__init__.py
@@ -0,0 +1,961 @@
+from contextlib import contextmanager
+import linecache
+import os
+from io import StringIO
+import sys
+import unittest
+from test import support
+from test.support.script_helper import assert_python_ok, assert_python_failure
+
+from test.test_warnings.data import stacklevel as warning_tests
+
+import warnings as original_warnings
+
+py_warnings = support.import_fresh_module('warnings', blocked=['_warnings'])
+c_warnings = support.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 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"]
+        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)
+            f()
+            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)
+
+    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"
+            self.module.warn(message, UserWarning)
+            self.assertTrue(message, w[-1].message)
+            self.module.warn(message, UserWarning)
+            self.assertTrue(w[-1].message, 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_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.assertTrue(w[-1].category is 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.assertTrue(w[-1].category is UserWarning)
+
+    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")
+
+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.assertTrue(w[-1].category is 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")
+
+    def test_stacklevel_import(self):
+        # Issue #24305: With stacklevel=2, module-level warnings should work.
+        support.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_missing_filename_not_main(self):
+        # If __file__ is not specified and __main__ is not the module name,
+        # then __file__ should be set to the module name.
+        filename = warning_tests.__file__
+        try:
+            del warning_tests.__file__
+            with warnings_state(self.module):
+                with original_warnings.catch_warnings(record=True,
+                        module=self.module) as w:
+                    warning_tests.inner("spam8", stacklevel=1)
+                    self.assertEqual(w[-1].filename, warning_tests.__name__)
+        finally:
+            warning_tests.__file__ = filename
+
+    @unittest.skipUnless(hasattr(sys, 'argv'), 'test needs sys.argv')
+    def test_missing_filename_main_with_argv(self):
+        # If __file__ is not specified and the caller is __main__ and sys.argv
+        # exists, then use sys.argv[0] as the file.
+        filename = warning_tests.__file__
+        module_name = warning_tests.__name__
+        try:
+            del warning_tests.__file__
+            warning_tests.__name__ = '__main__'
+            with warnings_state(self.module):
+                with original_warnings.catch_warnings(record=True,
+                        module=self.module) as w:
+                    warning_tests.inner('spam9', stacklevel=1)
+                    self.assertEqual(w[-1].filename, sys.argv[0])
+        finally:
+            warning_tests.__file__ = filename
+            warning_tests.__name__ = module_name
+
+    def test_missing_filename_main_without_argv(self):
+        # If __file__ is not specified, the caller is __main__, and sys.argv
+        # is not set, then '__main__' is the file name.
+        filename = warning_tests.__file__
+        module_name = warning_tests.__name__
+        argv = sys.argv
+        try:
+            del warning_tests.__file__
+            warning_tests.__name__ = '__main__'
+            del sys.argv
+            with warnings_state(self.module):
+                with original_warnings.catch_warnings(record=True,
+                        module=self.module) as w:
+                    warning_tests.inner('spam10', stacklevel=1)
+                    self.assertEqual(w[-1].filename, '__main__')
+        finally:
+            warning_tests.__file__ = filename
+            warning_tests.__name__ = module_name
+            sys.argv = argv
+
+    def test_missing_filename_main_with_argv_empty_string(self):
+        # If __file__ is not specified, the caller is __main__, and sys.argv[0]
+        # is the empty string, then '__main__ is the file name.
+        # Tests issue 2743.
+        file_name = warning_tests.__file__
+        module_name = warning_tests.__name__
+        argv = sys.argv
+        try:
+            del warning_tests.__file__
+            warning_tests.__name__ = '__main__'
+            sys.argv = ['']
+            with warnings_state(self.module):
+                with original_warnings.catch_warnings(record=True,
+                        module=self.module) as w:
+                    warning_tests.inner('spam11', stacklevel=1)
+                    self.assertEqual(w[-1].filename, '__main__')
+        finally:
+            warning_tests.__file__ = file_name
+            warning_tests.__name__ = module_name
+            sys.argv = argv
+
+    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)
+            for filename in ("nonascii\xe9\u20ac", "surrogate\udc80"):
+                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)
+
+class CWarnTests(WarnTests, unittest.TestCase):
+    module = c_warnings
+
+    # As an early adopter, we sanity check the
+    # test.support.import_fresh_module utility function
+    def test_accelerated(self):
+        self.assertFalse(original_warnings is self.module)
+        self.assertFalse(hasattr(self.module.warn, '__code__'))
+
+class PyWarnTests(WarnTests, unittest.TestCase):
+    module = py_warnings
+
+    # As an early adopter, we sanity check the
+    # test.support.import_fresh_module utility function
+    def test_pure_python(self):
+        self.assertFalse(original_warnings is 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')
+            self.module._setoption('error::Warning::0')
+            self.assertRaises(UserWarning, self.module.warn, 'convert to error')
+
+    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)
+
+    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 CWCmdLineTests(WCmdLineTests, unittest.TestCase):
+    module = c_warnings
+
+class PyWCmdLineTests(WCmdLineTests, unittest.TestCase):
+    module = py_warnings
+
+
+class _WarningsTests(BaseTest, unittest.TestCase):
+
+    """Tests specific to the _warnings module."""
+
+    module = c_warnings
+
+    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')
+
+    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
+
+    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)
+
+    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 showarning() 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)
+
+    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)
+
+
+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 = 3
+        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())
+
+class CWarningsDisplayTests(WarningsDisplayTests, unittest.TestCase):
+    module = c_warnings
+
+class PyWarningsDisplayTests(WarningsDisplayTests, unittest.TestCase):
+    module = py_warnings
+
+
+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.assertTrue(wmod.filters is orig_filters)
+        self.assertTrue(wmod.showwarning is orig_showwarning)
+        # Same test, but with recording disabled
+        with wmod.catch_warnings(module=wmod, record=False):
+            wmod.filters = wmod.showwarning = object()
+        self.assertTrue(wmod.filters is orig_filters)
+        self.assertTrue(wmod.showwarning is 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.assertTrue(type(w) is 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.assertTrue(w is None)
+            self.assertTrue(wmod.showwarning is 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.assertTrue(w is None)
+            self.assertTrue(wmod.showwarning is orig_showwarning)
+            self.assertTrue(wmod.filters is not orig_filters)
+        self.assertTrue(wmod.filters is orig_filters)
+        if wmod is sys.modules['warnings']:
+            # Ensure the default module is this one
+            with wmod.catch_warnings() as w:
+                self.assertTrue(w is None)
+                self.assertTrue(wmod.showwarning is orig_showwarning)
+                self.assertTrue(wmod.filters is not orig_filters)
+            self.assertTrue(wmod.filters is orig_filters)
+
+    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 support.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 support.check_warnings():
+            # defaults to quiet=True without argument
+            pass
+        with support.check_warnings(('foo', UserWarning)):
+            wmod.warn("foo")
+
+        with self.assertRaises(AssertionError):
+            with support.check_warnings(('', RuntimeWarning)):
+                # defaults to quiet=False with argument
+                pass
+        with self.assertRaises(AssertionError):
+            with support.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):
+
+    def test_single_warning(self):
+        rc, stdout, stderr = assert_python_ok("-c",
+            "import sys; sys.stdout.write(str(sys.warnoptions))",
+            PYTHONWARNINGS="ignore::DeprecationWarning")
+        self.assertEqual(stdout, b"['ignore::DeprecationWarning']")
+
+    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")
+        self.assertEqual(stdout,
+            b"['ignore::DeprecationWarning', 'ignore::UnicodeWarning']")
+
+    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")
+        self.assertEqual(stdout,
+            b"['ignore::DeprecationWarning', 'ignore::UnicodeWarning']")
+
+    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")
+        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"DeprecationWarning: Message"])
+
+    @unittest.skipUnless(sys.getfilesystemencoding() != 'ascii',
+                         'requires non-ascii filesystemencoding')
+    def test_nonascii(self):
+        rc, stdout, stderr = assert_python_ok("-c",
+            "import sys; sys.stdout.write(str(sys.warnoptions))",
+            PYTHONIOENCODING="utf-8",
+            PYTHONWARNINGS="ignore:DeprecaciónWarning")
+        self.assertEqual(stdout,
+            "['ignore:DeprecaciónWarning']".encode('utf-8'))
+
+class CEnvironmentVariableTests(EnvironmentVariableTests, unittest.TestCase):
+    module = c_warnings
+
+class PyEnvironmentVariableTests(EnvironmentVariableTests, unittest.TestCase):
+    module = py_warnings
+
+
+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 support.temp_cwd() as cwd, support.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):
+    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)
+        # note: "__main__" filename is not correct, it should be the name
+        # of the script
+        self.assertEqual(err, b'__main__:7: UserWarning: test')
+
+
+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 0000000..44e52ec
--- /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 0000000..32daec1
--- /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/stacklevel.py b/Lib/test/test_warnings/data/stacklevel.py
new file mode 100644
index 0000000..d0519ef
--- /dev/null
+++ b/Lib/test/test_warnings/data/stacklevel.py
@@ -0,0 +1,9 @@
+# Helper module for testing the skipmodules argument of warnings.warn()
+
+import warnings
+
+def outer(message, stacklevel=1):
+    inner(message, stacklevel)
+
+def inner(message, stacklevel=1):
+    warnings.warn(message, stacklevel=stacklevel)