cpython/Lib/test/test_warnings.py

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import warnings
import os
import unittest
from test import test_support
# The warnings module isn't easily tested, because it relies on module
# globals to store configuration information. setUp() and tearDown()
# preserve the current settings to avoid bashing them while running tests.
# To capture the warning messages, a replacement for showwarning() is
# used to save warning information in a global variable.
class WarningMessage:
"Holds results of latest showwarning() call"
pass
def showwarning(message, category, filename, lineno, file=None):
msg.message = str(message)
msg.category = category.__name__
msg.filename = os.path.basename(filename)
msg.lineno = lineno
class TestModule(unittest.TestCase):
def setUp(self):
global msg
msg = WarningMessage()
self._filters = warnings.filters[:]
self._showwarning = warnings.showwarning
warnings.showwarning = showwarning
self.ignored = [w[2].__name__ for w in self._filters
if w[0]=='ignore' and w[1] is None and w[3] is None]
def tearDown(self):
warnings.filters = self._filters[:]
warnings.showwarning = self._showwarning
def test_warn_default_category(self):
for i in range(4):
text = 'multi %d' %i # Different text on each call
warnings.warn(text)
self.assertEqual(msg.message, text)
self.assertEqual(msg.category, 'UserWarning')
def test_warn_specific_category(self):
text = 'None'
for category in [DeprecationWarning, FutureWarning, OverflowWarning,
PendingDeprecationWarning, RuntimeWarning,
SyntaxWarning, UserWarning, Warning]:
if category.__name__ in self.ignored:
text = 'filtered out' + category.__name__
warnings.warn(text, category)
self.assertNotEqual(msg.message, text)
else:
text = 'unfiltered %s' % category.__name__
warnings.warn(text, category)
self.assertEqual(msg.message, text)
self.assertEqual(msg.category, category.__name__)
def test_filtering(self):
warnings.filterwarnings("error", "", Warning, "", 0)
self.assertRaises(UserWarning, warnings.warn, 'convert to error')
warnings.resetwarnings()
text = 'handle normally'
warnings.warn(text)
self.assertEqual(msg.message, text)
self.assertEqual(msg.category, 'UserWarning')
warnings.filterwarnings("ignore", "", Warning, "", 0)
text = 'filtered out'
warnings.warn(text)
self.assertNotEqual(msg.message, text)
warnings.resetwarnings()
warnings.filterwarnings("error", "hex*", Warning, "", 0)
self.assertRaises(UserWarning, warnings.warn, 'hex/oct')
text = 'nonmatching text'
warnings.warn(text)
self.assertEqual(msg.message, text)
self.assertEqual(msg.category, 'UserWarning')
def test_main(verbose=None):
test_support.run_unittest(TestModule)
if __name__ == "__main__":
test_main(verbose=True)