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Editing: import_helper.py
import contextlib import _imp import importlib import importlib.util import os import shutil import sys import unittest import warnings from .os_helper import unlink @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) 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)
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