from contextlib import contextmanager import linecache import os from io import StringIO import sys import unittest import subprocess from test import support from test.script_helper import assert_python_ok from test import 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): # 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 super(BaseTest, self).setUp() def tearDown(self): sys.modules['warnings'] = original_warnings super(BaseTest, self).tearDown() 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_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_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_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, "test_warnings.py", 42) self.assertEqual(w[-1].message, message) del w[:] self.module.warn_explicit(message, UserWarning, "test_warnings.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) 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), "warning_tests.py") warning_tests.outer("spam2") self.assertEqual(os.path.basename(w[-1].filename), "warning_tests.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), "warning_tests.py") warning_tests.outer("spam4", stacklevel=1) self.assertEqual(os.path.basename(w[-1].filename), "warning_tests.py") warning_tests.inner("spam5", stacklevel=2) self.assertEqual(os.path.basename(w[-1].filename), "test_warnings.py") warning_tests.outer("spam6", stacklevel=2) self.assertEqual(os.path.basename(w[-1].filename), "warning_tests.py") warning_tests.outer("spam6.5", stacklevel=3) self.assertEqual(os.path.basename(w[-1].filename), "test_warnings.py") warning_tests.inner("spam7", stacklevel=9999) self.assertEqual(os.path.basename(w[-1].filename), "sys") 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_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()) 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 # 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, "", 42, registry=registry) self.assertEqual(w[-1].message, message) self.assertEqual(len(w), 1) self.assertEqual(len(registry), 1) del w[:] # Test removal. del self.module.defaultaction __warningregistry__ = {} registry = {} self.module.warn_explicit(message, UserWarning, "", 43, registry=registry) self.assertEqual(w[-1].message, message) self.assertEqual(len(w), 1) self.assertEqual(len(registry), 1) del w[:] # Test setting. self.module.defaultaction = "ignore" __warningregistry__ = {} registry = {} self.module.warn_explicit(message, UserWarning, "", 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 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): newenv = os.environ.copy() newenv["PYTHONWARNINGS"] = "ignore::DeprecationWarning" p = subprocess.Popen([sys.executable, "-c", "import sys; sys.stdout.write(str(sys.warnoptions))"], stdout=subprocess.PIPE, env=newenv) self.assertEqual(p.communicate()[0], b"['ignore::DeprecationWarning']") self.assertEqual(p.wait(), 0) def test_comma_separated_warnings(self): newenv = os.environ.copy() newenv["PYTHONWARNINGS"] = ("ignore::DeprecationWarning," "ignore::UnicodeWarning") p = subprocess.Popen([sys.executable, "-c", "import sys; sys.stdout.write(str(sys.warnoptions))"], stdout=subprocess.PIPE, env=newenv) self.assertEqual(p.communicate()[0], b"['ignore::DeprecationWarning', 'ignore::UnicodeWarning']") self.assertEqual(p.wait(), 0) def test_envvar_and_command_line(self): newenv = os.environ.copy() newenv["PYTHONWARNINGS"] = "ignore::DeprecationWarning" p = subprocess.Popen([sys.executable, "-W" "ignore::UnicodeWarning", "-c", "import sys; sys.stdout.write(str(sys.warnoptions))"], stdout=subprocess.PIPE, env=newenv) self.assertEqual(p.communicate()[0], b"['ignore::UnicodeWarning', 'ignore::DeprecationWarning']") self.assertEqual(p.wait(), 0) @unittest.skipUnless(sys.getfilesystemencoding() != 'ascii', 'requires non-ascii filesystemencoding') def test_nonascii(self): newenv = os.environ.copy() newenv["PYTHONWARNINGS"] = "ignore:DeprecaciónWarning" newenv["PYTHONIOENCODING"] = "utf-8" p = subprocess.Popen([sys.executable, "-c", "import sys; sys.stdout.write(str(sys.warnoptions))"], stdout=subprocess.PIPE, env=newenv) self.assertEqual(p.communicate()[0], "['ignore:DeprecaciónWarning']".encode('utf-8')) self.assertEqual(p.wait(), 0) 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'): env = os.environ.copy() env['PYTHONPATH'] = cwd # encodings loaded by initfsencoding() retcode = subprocess.call([sys.executable, '-c', 'pass'], env=env) self.assertEqual(retcode, 0) # Use -W to load warnings module at startup retcode = subprocess.call( [sys.executable, '-c', 'pass', '-W', 'always'], env=env) self.assertEqual(retcode, 0) def setUpModule(): py_warnings.onceregistry.clear() c_warnings.onceregistry.clear() tearDownModule = setUpModule if __name__ == "__main__": unittest.main()