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import contextlib
import _imp
import importlib
import importlib.util
import os
import shutil
import sys
import unittest
import warnings
from .os_helper import unlink, temp_dir
@contextlib.contextmanager
def _ignore_deprecated_imports(ignore=True):
"""Context manager to suppress package and module deprecation
warnings when importing them.
If ignore is False, this context manager has no effect.
"""
if ignore:
with warnings.catch_warnings():
warnings.filterwarnings("ignore", ".+ (module|package)",
DeprecationWarning)
yield
else:
yield
def unload(name):
try:
del sys.modules[name]
except KeyError:
pass
def forget(modname):
"""'Forget' a module was ever imported.
This removes the module from sys.modules and deletes any PEP 3147/488 or
legacy .pyc files.
"""
unload(modname)
for dirname in sys.path:
source = os.path.join(dirname, modname + '.py')
# It doesn't matter if they exist or not, unlink all possible
# combinations of PEP 3147/488 and legacy pyc files.
unlink(source + 'c')
for opt in ('', 1, 2):
unlink(importlib.util.cache_from_source(source, optimization=opt))
def make_legacy_pyc(source):
"""Move a PEP 3147/488 pyc file to its legacy pyc location.
:param source: The file system path to the source file. The source file
does not need to exist, however the PEP 3147/488 pyc file must exist.
:return: The file system path to the legacy pyc file.
"""
pyc_file = importlib.util.cache_from_source(source)
up_one = os.path.dirname(os.path.abspath(source))
legacy_pyc = os.path.join(up_one, source + 'c')
shutil.move(pyc_file, legacy_pyc)
return legacy_pyc
def import_module(name, deprecated=False, *, required_on=()):
"""Import and return the module to be tested, raising SkipTest if
it is not available.
If deprecated is True, any module or package deprecation messages
will be suppressed. If a module is required on a platform but optional for
others, set required_on to an iterable of platform prefixes which will be
compared against sys.platform.
"""
with _ignore_deprecated_imports(deprecated):
try:
return importlib.import_module(name)
except ImportError as msg:
if sys.platform.startswith(tuple(required_on)):
raise
raise unittest.SkipTest(str(msg))
def _save_and_remove_modules(names):
orig_modules = {}
prefixes = tuple(name + '.' for name in names)
for modname in list(sys.modules):
if modname in names or modname.startswith(prefixes):
orig_modules[modname] = sys.modules.pop(modname)
return orig_modules
@contextlib.contextmanager
def frozen_modules(enabled=True):
"""Force frozen modules to be used (or not).
This only applies to modules that haven't been imported yet.
Also, some essential modules will always be imported frozen.
"""
_imp._override_frozen_modules_for_tests(1 if enabled else -1)
try:
yield
finally:
_imp._override_frozen_modules_for_tests(0)
@contextlib.contextmanager
def multi_interp_extensions_check(enabled=True):
"""Force legacy modules to be allowed in subinterpreters (or not).
("legacy" == single-phase init)
This only applies to modules that haven't been imported yet.
It overrides the PyInterpreterConfig.check_multi_interp_extensions
setting (see support.run_in_subinterp_with_config() and
_xxsubinterpreters.create()).
Also see importlib.utils.allowing_all_extensions().
"""
old = _imp._override_multi_interp_extensions_check(1 if enabled else -1)
try:
yield
finally:
_imp._override_multi_interp_extensions_check(old)
def import_fresh_module(name, fresh=(), blocked=(), *,
deprecated=False,
usefrozen=False,
):
"""Import and return a module, deliberately bypassing sys.modules.
This function imports and returns a fresh copy of the named Python module
by removing the named module from sys.modules before doing the import.
Note that unlike reload, the original module is not affected by
this operation.
*fresh* is an iterable of additional module names that are also removed
from the sys.modules cache before doing the import. If one of these
modules can't be imported, None is returned.
*blocked* is an iterable of module names that are replaced with None
in the module cache during the import to ensure that attempts to import
them raise ImportError.
The named module and any modules named in the *fresh* and *blocked*
parameters are saved before starting the import and then reinserted into
sys.modules when the fresh import is complete.
Module and package deprecation messages are suppressed during this import
if *deprecated* is True.
This function will raise ImportError if the named module cannot be
imported.
If "usefrozen" is False (the default) then the frozen importer is
disabled (except for essential modules like importlib._bootstrap).
"""
# NOTE: test_heapq, test_json and test_warnings include extra sanity checks
# to make sure that this utility function is working as expected
with _ignore_deprecated_imports(deprecated):
# Keep track of modules saved for later restoration as well
# as those which just need a blocking entry removed
fresh = list(fresh)
blocked = list(blocked)
names = {name, *fresh, *blocked}
orig_modules = _save_and_remove_modules(names)
for modname in blocked:
sys.modules[modname] = None
try:
with frozen_modules(usefrozen):
# Return None when one of the "fresh" modules can not be imported.
try:
for modname in fresh:
__import__(modname)
except ImportError:
return None
return importlib.import_module(name)
finally:
_save_and_remove_modules(names)
sys.modules.update(orig_modules)
class CleanImport(object):
"""Context manager to force import to return a new module reference.
This is useful for testing module-level behaviours, such as
the emission of a DeprecationWarning on import.
Use like this:
with CleanImport("foo"):
importlib.import_module("foo") # new reference
If "usefrozen" is False (the default) then the frozen importer is
disabled (except for essential modules like importlib._bootstrap).
"""
def __init__(self, *module_names, usefrozen=False):
self.original_modules = sys.modules.copy()
for module_name in module_names:
if module_name in sys.modules:
module = sys.modules[module_name]
# It is possible that module_name is just an alias for
# another module (e.g. stub for modules renamed in 3.x).
# In that case, we also need delete the real module to clear
# the import cache.
if module.__name__ != module_name:
del sys.modules[module.__name__]
del sys.modules[module_name]
self._frozen_modules = frozen_modules(usefrozen)
def __enter__(self):
self._frozen_modules.__enter__()
return self
def __exit__(self, *ignore_exc):
sys.modules.update(self.original_modules)
self._frozen_modules.__exit__(*ignore_exc)
class DirsOnSysPath(object):
"""Context manager to temporarily add directories to sys.path.
This makes a copy of sys.path, appends any directories given
as positional arguments, then reverts sys.path to the copied
settings when the context ends.
Note that *all* sys.path modifications in the body of the
context manager, including replacement of the object,
will be reverted at the end of the block.
"""
def __init__(self, *paths):
self.original_value = sys.path[:]
self.original_object = sys.path
sys.path.extend(paths)
def __enter__(self):
return self
def __exit__(self, *ignore_exc):
sys.path = self.original_object
sys.path[:] = self.original_value
def modules_setup():
return sys.modules.copy(),
def modules_cleanup(oldmodules):
# Encoders/decoders are registered permanently within the internal
# codec cache. If we destroy the corresponding modules their
# globals will be set to None which will trip up the cached functions.
encodings = [(k, v) for k, v in sys.modules.items()
if k.startswith('encodings.')]
sys.modules.clear()
sys.modules.update(encodings)
# XXX: This kind of problem can affect more than just encodings.
# In particular extension modules (such as _ssl) don't cope
# with reloading properly. Really, test modules should be cleaning
# out the test specific modules they know they added (ala test_runpy)
# rather than relying on this function (as test_importhooks and test_pkg
# do currently). Implicitly imported *real* modules should be left alone
# (see issue 10556).
sys.modules.update(oldmodules)
@contextlib.contextmanager
def isolated_modules():
"""
Save modules on entry and cleanup on exit.
"""
(saved,) = modules_setup()
try:
yield
finally:
modules_cleanup(saved)
def mock_register_at_fork(func):
# bpo-30599: Mock os.register_at_fork() when importing the random module,
# since this function doesn't allow to unregister callbacks and would leak
# memory.
from unittest import mock
return mock.patch('os.register_at_fork', create=True)(func)
@contextlib.contextmanager
def ready_to_import(name=None, source=""):
from test.support import script_helper
# 1. Sets up a temporary directory and removes it afterwards
# 2. Creates the module file
# 3. Temporarily clears the module from sys.modules (if any)
# 4. Reverts or removes the module when cleaning up
name = name or "spam"
with temp_dir() as tempdir:
path = script_helper.make_script(tempdir, name, source)
old_module = sys.modules.pop(name, None)
try:
sys.path.insert(0, tempdir)
yield name, path
sys.path.remove(tempdir)
finally:
if old_module is not None:
sys.modules[name] = old_module
else:
sys.modules.pop(name, None)