Editing: warnings_helper.py
import contextlib import functools import re import sys import warnings def check_syntax_warning(testcase, statement, errtext='', *, lineno=1, offset=None): # Test also that a warning is emitted only once. from test.support import check_syntax_error with warnings.catch_warnings(record=True) as warns: warnings.simplefilter('always', SyntaxWarning) compile(statement, '<testcase>', 'exec') testcase.assertEqual(len(warns), 1, warns) warn, = warns testcase.assertTrue(issubclass(warn.category, SyntaxWarning), warn.category) if errtext: testcase.assertRegex(str(warn.message), errtext) testcase.assertEqual(warn.filename, '<testcase>') testcase.assertIsNotNone(warn.lineno) if lineno is not None: testcase.assertEqual(warn.lineno, lineno) # SyntaxWarning should be converted to SyntaxError when raised, # since the latter contains more information and provides better # error report. with warnings.catch_warnings(record=True) as warns: warnings.simplefilter('error', SyntaxWarning) check_syntax_error(testcase, statement, errtext, lineno=lineno, offset=offset) # No warnings are leaked when a SyntaxError is raised. testcase.assertEqual(warns, []) def ignore_warnings(*, category): """Decorator to suppress warnings. Use of context managers to hide warnings make diffs more noisy and tools like 'git blame' less useful. """ def decorator(test): @functools.wraps(test) def wrapper(self, *args, **kwargs): with warnings.catch_warnings(): warnings.simplefilter('ignore', category=category) return test(self, *args, **kwargs) return wrapper return decorator class WarningsRecorder(object): """Convenience wrapper for the warnings list returned on entry to the warnings.catch_warnings() context manager. """ def __init__(self, warnings_list): self._warnings = warnings_list self._last = 0 def __getattr__(self, attr): if len(self._warnings) > self._last: return getattr(self._warnings[-1], attr) elif attr in warnings.WarningMessage._WARNING_DETAILS: return None raise AttributeError("%r has no attribute %r" % (self, attr)) @property def warnings(self): return self._warnings[self._last:] def reset(self): self._last = len(self._warnings) @contextlib.contextmanager def check_warnings(*filters, **kwargs): """Context manager to silence warnings. Accept 2-tuples as positional arguments: ("message regexp", WarningCategory) Optional argument: - if 'quiet' is True, it does not fail if a filter catches nothing (default True without argument, default False if some filters are defined) Without argument, it defaults to: check_warnings(("", Warning), quiet=True) """ quiet = kwargs.get('quiet') if not filters: filters = (("", Warning),) # Preserve backward compatibility if quiet is None: quiet = True return _filterwarnings(filters, quiet) @contextlib.contextmanager def check_no_warnings(testcase, message='', category=Warning, force_gc=False): """Context manager to check that no warnings are emitted. This context manager enables a given warning within its scope and checks that no warnings are emitted even with that warning enabled. If force_gc is True, a garbage collection is attempted before checking for warnings. This may help to catch warnings emitted when objects are deleted, such as ResourceWarning. Other keyword arguments are passed to warnings.filterwarnings(). """ from test.support import gc_collect with warnings.catch_warnings(record=True) as warns: warnings.filterwarnings('always', message=message, category=category) yield if force_gc: gc_collect() testcase.assertEqual(warns, []) @contextlib.contextmanager def check_no_resource_warning(testcase): """Context manager to check that no ResourceWarning is emitted. Usage: with check_no_resource_warning(self): f = open(...) ... del f You must remove the object which may emit ResourceWarning before the end of the context manager. """ with check_no_warnings(testcase, category=ResourceWarning, force_gc=True): yield def _filterwarnings(filters, quiet=False): """Catch the warnings, then check if all the expected warnings have been raised and re-raise unexpected warnings. If 'quiet' is True, only re-raise the unexpected warnings. """ # Clear the warning registry of the calling module # in order to re-raise the warnings. frame = sys._getframe(2) registry = frame.f_globals.get('__warningregistry__') if registry: registry.clear() with warnings.catch_warnings(record=True) as w: # Set filter "always" to record all warnings. Because # test_warnings swap the module, we need to look up in # the sys.modules dictionary. sys.modules['warnings'].simplefilter("always") yield WarningsRecorder(w) # Filter the recorded warnings reraise = list(w) missing = [] for msg, cat in filters: seen = False for w in reraise[:]: warning = w.message # Filter out the matching messages if (re.match(msg, str(warning), re.I) and issubclass(warning.__class__, cat)): seen = True reraise.remove(w) if not seen and not quiet: # This filter caught nothing missing.append((msg, cat.__name__)) if reraise: raise AssertionError("unhandled warning %s" % reraise[0]) if missing: raise AssertionError("filter (%r, %s) did not catch any warning" % missing[0]) @contextlib.contextmanager def save_restore_warnings_filters(): old_filters = warnings.filters[:] try: yield finally: warnings.filters[:] = old_filters def _warn_about_deprecation(): warnings.warn( "This is used in test_support test to ensure" " support.ignore_deprecations_from() works as expected." " You should not be seeing this.", DeprecationWarning, stacklevel=0, )
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