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Issue #3781: Final cleanup of warnings.catch_warnings and its usage in the test suite. Closes issue w.r.t. 2.6 (R: Brett Cannon)

This commit is contained in:
Nick Coghlan 2008-09-11 12:11:06 +00:00
parent 9fa5a2828c
commit d2e0938362
11 changed files with 254 additions and 93 deletions
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41
Doc/library/test.rst
View File

@ -291,18 +291,26 @@ The :mod:`test.test_support` module defines the following functions:
This will run all tests defined in the named module.
.. function:: catch_warning(module=warnings, record=True)
.. function:: check_warnings()
Return a context manager that guards the warnings filter from being
permanently changed and optionally alters the :func:`showwarning`
function to record the details of any warnings that are issued in the
managed context. Details of the most recent call to :func:`showwarning`
are saved directly on the context manager, while details of previous
warnings can be retrieved from the ``warnings`` list.
A convenience wrapper for ``warnings.catch_warnings()`` that makes
it easier to test that a warning was correctly raised with a single
assertion. It is approximately equivalent to calling
``warnings.catch_warnings(record=True)``.
The main difference is that on entry to the context manager, a
:class:`WarningRecorder` instance is returned instead of a simple list.
The underlying warnings list is available via the recorder object's
:attr:`warnings` attribute, while the attributes of the last raised
warning are also accessible directly on the object. If no warning has
been raised, then the latter attributes will all be :const:`None`.
A :meth:`reset` method is also provided on the recorder object. This
method simply clears the warning list.
The context manager is used like this::
with catch_warning() as w:
with check_warnings() as w:
warnings.simplefilter("always")
warnings.warn("foo")
assert str(w.message) == "foo"
@ -310,15 +318,8 @@ The :mod:`test.test_support` module defines the following functions:
assert str(w.message) == "bar"
assert str(w.warnings[0].message) == "foo"
assert str(w.warnings[1].message) == "bar"
By default, the real :mod:`warnings` module is affected - the ability
to select a different module is provided for the benefit of the
:mod:`warnings` module's own unit tests.
The ``record`` argument specifies whether or not the :func:`showwarning`
function is replaced. Note that recording the warnings in this fashion
also prevents them from being written to sys.stderr. If set to ``False``,
the standard handling of warning messages is left in place (however, the
original handling is still restored at the end of the block).
w.reset()
assert len(w.warnings) == 0
.. versionadded:: 2.6
@ -366,4 +367,10 @@ The :mod:`test.test_support` module defines the following classes:
Temporarily unset the environment variable ``envvar``.
.. class:: WarningsRecorder()
Class used to record warnings for unit tests. See documentation of
:func:`check_warnings` above for more details.
.. versionadded:: 2.6

32
Doc/library/warnings.rst
View File

@ -163,9 +163,9 @@ ImportWarning can also be enabled explicitly in Python code using::
Temporarily Suppressing Warnings
--------------------------------
If you are using code that you know will raise a warning, such some deprecated
function, but do not want to see the warning, then suppress the warning using
the :class:`catch_warnings` context manager::
If you are using code that you know will raise a warning, such as a deprecated
function, but do not want to see the warning, then it is possible to suppress
the warning using the :class:`catch_warnings` context manager::
import warnings
@ -216,7 +216,15 @@ the warning has been cleared.
Once the context manager exits, the warnings filter is restored to its state
when the context was entered. This prevents tests from changing the warnings
filter in unexpected ways between tests and leading to indeterminate test
results.
results. The :func:`showwarning` function in the module is also restored to
its original value.
When testing multiple operations that raise the same kind of warning, it
is important to test them in a manner that confirms each operation is raising
a new warning (e.g. set warnings to be raised as exceptions and check the
operations raise exceptions, check that the length of the warning list
continues to increase after each operation, or else delete the previous
entries from the warnings list before each new operation).
.. _warning-functions:
@ -330,16 +338,18 @@ Available Context Managers
.. class:: catch_warnings([\*, record=False, module=None])
A context manager that copies and, upon exit, restores the warnings filter.
If the *record* argument is False (the default) the context manager returns
:class:`None`. If *record* is true, a list is returned that is populated
with objects as seen by a custom :func:`showwarning` function (which also
suppresses output to ``sys.stdout``). Each object has attributes with the
same names as the arguments to :func:`showwarning`.
A context manager that copies and, upon exit, restores the warnings filter
and the :func:`showwarning` function.
If the *record* argument is :const:`False` (the default) the context manager
returns :class:`None` on entry. If *record* is :const:`True`, a list is
returned that is progressively populated with objects as seen by a custom
:func:`showwarning` function (which also suppresses output to ``sys.stdout``).
Each object in the list has attributes with the same names as the arguments to
:func:`showwarning`.
The *module* argument takes a module that will be used instead of the
module returned when you import :mod:`warnings` whose filter will be
protected. This arguments exists primarily for testing the :mod:`warnings`
protected. This argument exists primarily for testing the :mod:`warnings`
module itself.
.. note::

14
Lib/test/test_import.py
View File

@ -5,7 +5,7 @@ import shutil
import sys
import py_compile
import warnings
from test.test_support import unlink, TESTFN, unload, run_unittest
from test.test_support import unlink, TESTFN, unload, run_unittest, check_warnings
def remove_files(name):
@ -279,17 +279,17 @@ class RelativeImport(unittest.TestCase):
check_relative()
# Check relative fails with only __package__ wrong
ns = dict(__package__='foo', __name__='test.notarealmodule')
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
check_absolute()
self.assert_('foo' in str(w[-1].message))
self.assertEqual(w[-1].category, RuntimeWarning)
self.assert_('foo' in str(w.message))
self.assertEqual(w.category, RuntimeWarning)
self.assertRaises(SystemError, check_relative)
# Check relative fails with __package__ and __name__ wrong
ns = dict(__package__='foo', __name__='notarealpkg.notarealmodule')
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
check_absolute()
self.assert_('foo' in str(w[-1].message))
self.assertEqual(w[-1].category, RuntimeWarning)
self.assert_('foo' in str(w.message))
self.assertEqual(w.category, RuntimeWarning)
self.assertRaises(SystemError, check_relative)
# Check both fail with package set to a non-string
ns = dict(__package__=object())

125
Lib/test/test_py3kwarn.py
View File

@ -1,6 +1,7 @@
import unittest
import sys
from test.test_support import CleanImport, TestSkipped, run_unittest
from test.test_support import (check_warnings, CleanImport,
TestSkipped, run_unittest)
import warnings
from contextlib import nested
@ -8,15 +9,22 @@ from contextlib import nested
if not sys.py3kwarning:
raise TestSkipped('%s must be run with the -3 flag' % __name__)
def reset_module_registry(module):
try:
registry = module.__warningregistry__
except AttributeError:
pass
else:
registry.clear()
class TestPy3KWarnings(unittest.TestCase):
def assertWarning(self, _, warning, expected_message):
self.assertEqual(str(warning[-1].message), expected_message)
self.assertEqual(str(warning.message), expected_message)
def test_backquote(self):
expected = 'backquote not supported in 3.x; use repr()'
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
exec "`2`" in {}
self.assertWarning(None, w, expected)
@ -27,55 +35,71 @@ class TestPy3KWarnings(unittest.TestCase):
exec expr in {'f' : f}
expected = "assignment to True or False is forbidden in 3.x"
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
safe_exec("True = False")
self.assertWarning(None, w, expected)
w.reset()
safe_exec("False = True")
self.assertWarning(None, w, expected)
w.reset()
try:
safe_exec("obj.False = True")
except NameError: pass
self.assertWarning(None, w, expected)
w.reset()
try:
safe_exec("obj.True = False")
except NameError: pass
self.assertWarning(None, w, expected)
w.reset()
safe_exec("def False(): pass")
self.assertWarning(None, w, expected)
w.reset()
safe_exec("def True(): pass")
self.assertWarning(None, w, expected)
w.reset()
safe_exec("class False: pass")
self.assertWarning(None, w, expected)
w.reset()
safe_exec("class True: pass")
self.assertWarning(None, w, expected)
w.reset()
safe_exec("def f(True=43): pass")
self.assertWarning(None, w, expected)
w.reset()
safe_exec("def f(False=None): pass")
self.assertWarning(None, w, expected)
w.reset()
safe_exec("f(False=True)")
self.assertWarning(None, w, expected)
w.reset()
safe_exec("f(True=1)")
self.assertWarning(None, w, expected)
def test_type_inequality_comparisons(self):
expected = 'type inequality comparisons not supported in 3.x'
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(int < str, w, expected)
w.reset()
self.assertWarning(type < object, w, expected)
def test_object_inequality_comparisons(self):
expected = 'comparing unequal types not supported in 3.x'
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(str < [], w, expected)
w.reset()
self.assertWarning(object() < (1, 2), w, expected)
def test_dict_inequality_comparisons(self):
expected = 'dict inequality comparisons not supported in 3.x'
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning({} < {2:3}, w, expected)
w.reset()
self.assertWarning({} <= {}, w, expected)
w.reset()
self.assertWarning({} > {2:3}, w, expected)
w.reset()
self.assertWarning({2:3} >= {}, w, expected)
def test_cell_inequality_comparisons(self):
@ -86,8 +110,9 @@ class TestPy3KWarnings(unittest.TestCase):
return g
cell0, = f(0).func_closure
cell1, = f(1).func_closure
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(cell0 == cell1, w, expected)
w.reset()
self.assertWarning(cell0 < cell1, w, expected)
def test_code_inequality_comparisons(self):
@ -96,10 +121,13 @@ class TestPy3KWarnings(unittest.TestCase):
pass
def g(x):
pass
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(f.func_code < g.func_code, w, expected)
w.reset()
self.assertWarning(f.func_code <= g.func_code, w, expected)
w.reset()
self.assertWarning(f.func_code >= g.func_code, w, expected)
w.reset()
self.assertWarning(f.func_code > g.func_code, w, expected)
def test_builtin_function_or_method_comparisons(self):
@ -107,10 +135,13 @@ class TestPy3KWarnings(unittest.TestCase):
'inequality comparisons not supported in 3.x')
func = eval
meth = {}.get
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(func < meth, w, expected)
w.reset()
self.assertWarning(func > meth, w, expected)
w.reset()
self.assertWarning(meth <= func, w, expected)
w.reset()
self.assertWarning(meth >= func, w, expected)
def test_sort_cmp_arg(self):
@ -118,15 +149,18 @@ class TestPy3KWarnings(unittest.TestCase):
lst = range(5)
cmp = lambda x,y: -1
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(lst.sort(cmp=cmp), w, expected)
w.reset()
self.assertWarning(sorted(lst, cmp=cmp), w, expected)
w.reset()
self.assertWarning(lst.sort(cmp), w, expected)
w.reset()
self.assertWarning(sorted(lst, cmp), w, expected)
def test_sys_exc_clear(self):
expected = 'sys.exc_clear() not supported in 3.x; use except clauses'
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(sys.exc_clear(), w, expected)
def test_methods_members(self):
@ -135,17 +169,17 @@ class TestPy3KWarnings(unittest.TestCase):
__methods__ = ['a']
__members__ = ['b']
c = C()
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(dir(c), w, expected)
def test_softspace(self):
expected = 'file.softspace not supported in 3.x'
with file(__file__) as f:
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(f.softspace, w, expected)
def set():
f.softspace = 0
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(set(), w, expected)
def test_slice_methods(self):
@ -161,59 +195,60 @@ class TestPy3KWarnings(unittest.TestCase):
expected = "in 3.x, __{0}slice__ has been removed; use __{0}item__"
for obj in (Spam(), Egg()):
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(obj[1:2], w, expected.format('get'))
w.reset()
del obj[3:4]
self.assertWarning(None, w, expected.format('del'))
w.reset()
obj[4:5] = "eggs"
self.assertWarning(None, w, expected.format('set'))
def test_tuple_parameter_unpacking(self):
expected = "tuple parameter unpacking has been removed in 3.x"
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
exec "def f((a, b)): pass"
self.assertWarning(None, w, expected)
def test_buffer(self):
expected = 'buffer() not supported in 3.x'
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(buffer('a'), w, expected)
def test_file_xreadlines(self):
expected = ("f.xreadlines() not supported in 3.x, "
"try 'for line in f' instead")
with file(__file__) as f:
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
self.assertWarning(f.xreadlines(), w, expected)
def test_hash_inheritance(self):
with warnings.catch_warnings(record=True) as w:
with check_warnings() as w:
# With object as the base class
class WarnOnlyCmp(object):
def __cmp__(self, other): pass
self.assertEqual(len(w), 1)
self.assertEqual(len(w.warnings), 1)
self.assertWarning(None, w,
"Overriding __cmp__ blocks inheritance of __hash__ in 3.x")
del w[:]
w.reset()
class WarnOnlyEq(object):
def __eq__(self, other): pass
self.assertEqual(len(w), 1)
self.assertEqual(len(w.warnings), 1)
self.assertWarning(None, w,
"Overriding __eq__ blocks inheritance of __hash__ in 3.x")
del w[:]
w.reset()
class WarnCmpAndEq(object):
def __cmp__(self, other): pass
def __eq__(self, other): pass
self.assertEqual(len(w), 2)
self.assertWarning(None, w[:1],
self.assertEqual(len(w.warnings), 2)
self.assertWarning(None, w.warnings[0],
"Overriding __cmp__ blocks inheritance of __hash__ in 3.x")
self.assertWarning(None, w,
"Overriding __eq__ blocks inheritance of __hash__ in 3.x")
del w[:]
w.reset()
class NoWarningOnlyHash(object):
def __hash__(self): pass
self.assertEqual(len(w), 0)
del w[:]
self.assertEqual(len(w.warnings), 0)
# With an intermediate class in the heirarchy
class DefinesAllThree(object):
def __cmp__(self, other): pass
@ -221,28 +256,28 @@ class TestPy3KWarnings(unittest.TestCase):
def __hash__(self): pass
class WarnOnlyCmp(DefinesAllThree):
def __cmp__(self, other): pass
self.assertEqual(len(w), 1)
self.assertEqual(len(w.warnings), 1)
self.assertWarning(None, w,
"Overriding __cmp__ blocks inheritance of __hash__ in 3.x")
del w[:]
w.reset()
class WarnOnlyEq(DefinesAllThree):
def __eq__(self, other): pass
self.assertEqual(len(w), 1)
self.assertEqual(len(w.warnings), 1)
self.assertWarning(None, w,
"Overriding __eq__ blocks inheritance of __hash__ in 3.x")
del w[:]
w.reset()
class WarnCmpAndEq(DefinesAllThree):
def __cmp__(self, other): pass
def __eq__(self, other): pass
self.assertEqual(len(w), 2)
self.assertWarning(None, w[:1],
self.assertEqual(len(w.warnings), 2)
self.assertWarning(None, w.warnings[0],
"Overriding __cmp__ blocks inheritance of __hash__ in 3.x")
self.assertWarning(None, w,
"Overriding __eq__ blocks inheritance of __hash__ in 3.x")
del w[:]
w.reset()
class NoWarningOnlyHash(DefinesAllThree):
def __hash__(self): pass
self.assertEqual(len(w), 0)
self.assertEqual(len(w.warnings), 0)
class TestStdlibRemovals(unittest.TestCase):
@ -283,6 +318,9 @@ class TestStdlibRemovals(unittest.TestCase):
"""Make sure the specified module, when imported, raises a
DeprecationWarning and specifies itself in the message."""
with nested(CleanImport(module_name), warnings.catch_warnings()):
# XXX: This is not quite enough for extension modules - those
# won't rerun their init code even with CleanImport.
# You can see this easily by running the whole test suite with -3
warnings.filterwarnings("error", ".+ removed",
DeprecationWarning, __name__)
try:
@ -320,12 +358,15 @@ class TestStdlibRemovals(unittest.TestCase):
def dumbo(where, names, args): pass
for path_mod in ("ntpath", "macpath", "os2emxpath", "posixpath"):
mod = __import__(path_mod)
with warnings.catch_warnings(record=True) as w:
reset_module_registry(mod)
with check_warnings() as w:
mod.walk("crashers", dumbo, None)
self.assertEquals(str(w[-1].message), msg)
self.assertEquals(str(w.message), msg)
def test_commands_members(self):
import commands
# commands module tests may have already triggered this warning
reset_module_registry(commands)
members = {"mk2arg" : 2, "mkarg" : 1, "getstatus" : 1}
for name, arg_count in members.items():
with warnings.catch_warnings():
@ -335,6 +376,8 @@ class TestStdlibRemovals(unittest.TestCase):
def test_reduce_move(self):
from operator import add
# reduce tests may have already triggered this warning
reset_module_registry(unittest)
with warnings.catch_warnings():
warnings.filterwarnings("error", "reduce")
self.assertRaises(DeprecationWarning, reduce, add, range(10))
@ -342,6 +385,8 @@ class TestStdlibRemovals(unittest.TestCase):
def test_mutablestring_removal(self):
# UserString.MutableString has been removed in 3.0.
import UserString
# UserString tests may have already triggered this warning
reset_module_registry(UserString)
with warnings.catch_warnings():
warnings.filterwarnings("error", ".*MutableString",
DeprecationWarning)
@ -349,7 +394,7 @@ class TestStdlibRemovals(unittest.TestCase):
def test_main():
with warnings.catch_warnings():
with check_warnings():
warnings.simplefilter("always")
run_unittest(TestPy3KWarnings,
TestStdlibRemovals)

14
Lib/test/test_structmembers.py
View File

@ -66,35 +66,35 @@ class ReadWriteTests(unittest.TestCase):
class TestWarnings(unittest.TestCase):
def has_warned(self, w):
self.assertEqual(w[-1].category, RuntimeWarning)
self.assertEqual(w.category, RuntimeWarning)
def test_byte_max(self):
with warnings.catch_warnings(record=True) as w:
with test_support.check_warnings() as w:
ts.T_BYTE = CHAR_MAX+1
self.has_warned(w)
def test_byte_min(self):
with warnings.catch_warnings(record=True) as w:
with test_support.check_warnings() as w:
ts.T_BYTE = CHAR_MIN-1
self.has_warned(w)
def test_ubyte_max(self):
with warnings.catch_warnings(record=True) as w:
with test_support.check_warnings() as w:
ts.T_UBYTE = UCHAR_MAX+1
self.has_warned(w)
def test_short_max(self):
with warnings.catch_warnings(record=True) as w:
with test_support.check_warnings() as w:
ts.T_SHORT = SHRT_MAX+1
self.has_warned(w)
def test_short_min(self):
with warnings.catch_warnings(record=True) as w:
with test_support.check_warnings() as w:
ts.T_SHORT = SHRT_MIN-1
self.has_warned(w)
def test_ushort_max(self):
with warnings.catch_warnings(record=True) as w:
with test_support.check_warnings() as w:
ts.T_USHORT = USHRT_MAX+1
self.has_warned(w)

2
Lib/test/test_sundry.py
View File

@ -8,7 +8,7 @@ import warnings
class TestUntestedModules(unittest.TestCase):
def test_at_least_import_untested_modules(self):
with warnings.catch_warnings(record=True):
with warnings.catch_warnings():
import CGIHTTPServer
import aifc
import audiodev

25
Lib/test/test_support.py
View File

@ -18,7 +18,7 @@ __all__ = ["Error", "TestFailed", "TestSkipped", "ResourceDenied", "import_modul
"is_resource_enabled", "requires", "find_unused_port", "bind_port",
"fcmp", "have_unicode", "is_jython", "TESTFN", "HOST", "FUZZ",
"findfile", "verify", "vereq", "sortdict", "check_syntax_error",
"open_urlresource", "CleanImport",
"open_urlresource", "check_warnings", "CleanImport",
"EnvironmentVarGuard", "captured_output",
"captured_stdout", "TransientResource", "transient_internet",
"run_with_locale", "set_memlimit", "bigmemtest", "bigaddrspacetest",
@ -381,6 +381,29 @@ def open_urlresource(url):
return open(fn)
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
def __getattr__(self, attr):
if self.warnings:
return getattr(self.warnings[-1], attr)
elif attr in warnings.WarningMessage._WARNING_DETAILS:
return None
raise AttributeError("%r has no attribute %r" % (self, attr))
def reset(self):
del self.warnings[:]
@contextlib.contextmanager
def check_warnings():
with warnings.catch_warnings(record=True) as w:
yield WarningsRecorder(w)
class CleanImport(object):
"""Context manager to force import to return a new module reference.

12
Lib/test/test_symtable.py
View File

@ -60,16 +60,16 @@ class SymtableTest(unittest.TestCase):
def check(w, msg):
self.assertEqual(str(w.message), msg)
sym = self.top.lookup("glob")
with warnings.catch_warnings(record=True) as w:
with test_support.check_warnings() as w:
warnings.simplefilter("always", DeprecationWarning)
self.assertFalse(sym.is_vararg())
check(w[-1].message, "is_vararg() is obsolete and will be removed")
check(w, "is_vararg() is obsolete and will be removed")
w.reset()
self.assertFalse(sym.is_keywordarg())
check(w[-1].message,
"is_keywordarg() is obsolete and will be removed")
check(w, "is_keywordarg() is obsolete and will be removed")
w.reset()
self.assertFalse(sym.is_in_tuple())
check(w[-1].message,
"is_in_tuple() is obsolete and will be removed")
check(w, "is_in_tuple() is obsolete and will be removed")
def test_type(self):
self.assertEqual(self.top.get_type(), "module")

57
Lib/test/test_warnings.py
View File

@ -517,10 +517,12 @@ class CatchWarningTests(BaseTest):
wmod = self.module
orig_filters = wmod.filters
orig_showwarning = wmod.showwarning
with wmod.catch_warnings(record=True, module=wmod):
# Ensure both showwarning and filters are restored when recording
with wmod.catch_warnings(module=wmod, record=True):
wmod.filters = wmod.showwarning = object()
self.assert_(wmod.filters is orig_filters)
self.assert_(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.assert_(wmod.filters is orig_filters)
@ -528,9 +530,10 @@ class CatchWarningTests(BaseTest):
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.assertRaises(AttributeError, getattr, w, 'message')
self.assert_(type(w) is list)
wmod.simplefilter("always")
wmod.warn("foo")
self.assertEqual(str(w[-1].message), "foo")
@ -540,11 +543,61 @@ class CatchWarningTests(BaseTest):
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.assert_(w is None)
self.assert_(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.assert_(w is None)
self.assert_(wmod.showwarning is orig_showwarning)
self.assert_(wmod.filters is not orig_filters)
self.assert_(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.assert_(w is None)
self.assert_(wmod.showwarning is orig_showwarning)
self.assert_(wmod.filters is not orig_filters)
self.assert_(wmod.filters is orig_filters)
def test_check_warnings(self):
# Explicit tests for the test_support convenience wrapper
wmod = self.module
if wmod is sys.modules['warnings']:
with test_support.check_warnings() 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, [])
class CCatchWarningTests(CatchWarningTests):
module = c_warnings

15
Lib/warnings.py
View File

@ -331,8 +331,21 @@ class catch_warnings(object):
"""
self._record = record
self._module = sys.modules['warnings'] if module is None else module
self._entered = False
def __repr__(self):
args = []
if self._record:
args.append("record=True")
if self._module is not sys.modules['warnings']:
args.append("module=%r" % self._module)
name = type(self).__name__
return "%s(%s)" % (name, ", ".join(args))
def __enter__(self):
if self._entered:
raise RuntimeError("Cannot enter %r twice" % self)
self._entered = True
self._filters = self._module.filters
self._module.filters = self._filters[:]
self._showwarning = self._module.showwarning
@ -346,6 +359,8 @@ class catch_warnings(object):
return None
def __exit__(self, *exc_info):
if not self._entered:
raise RuntimeError("Cannot exit %r without entering first" % self)
self._module.filters = self._filters
self._module.showwarning = self._showwarning

10
Misc/NEWS
View File

@ -79,9 +79,13 @@ Library
- Issue #3811: The Unicode database was updated to 5.1.
- Issue #3781: Further warnings.catch_warnings() cleanup to prevent
silent misbehaviour when a single instance is nested in multiple
with statements, or when the methods are invoked in the wrong order.
- Issue #3809: Fixed spurious 'test.blah' file left behind by test_logging.
- Issue 3781: Clean up the API for warnings.catch_warnings() by having it
- Issue #3781: Clean up the API for warnings.catch_warnings() by having it
return a list or None rather than a custom object.
- Issue #1638033: Cookie.Morsel gained the httponly attribute.
@ -142,6 +146,10 @@ Extension Modules
Tests
-----
- Issue #3781: Add test.test_support.check_warnings() as a convenience
wrapper for warnings.catch_warnings() that makes it easier to check
that expected warning messages are being reported.
- Issue #3796: Some tests functions were not enabled in test_float.
- Issue #3768: Move test_py3kwarn over to the new API for catch_warnings().