# Copyright 2014 Altera Corporation. All Rights Reserved. # Copyright 2015-2017 John McGehee # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """This module provides a base class derived from `unittest.TestClass` for unit tests using the :py:class:`pyfakefs` module. `fake_filesystem_unittest.TestCase` searches `sys.modules` for modules that import the `os`, `io`, `path` `shutil`, and `pathlib` modules. The `setUpPyfakefs()` method binds these modules to the corresponding fake modules from `pyfakefs`. Further, the `open()` built-in is bound to a fake `open()`. It is expected that `setUpPyfakefs()` be invoked at the beginning of the derived class' `setUp()` method. There is no need to add anything to the derived class' `tearDown()` method. During the test, everything uses the fake file system and modules. This means that even in your test fixture, familiar functions like `open()` and `os.makedirs()` manipulate the fake file system. Existing unit tests that use the real file system can be retrofitted to use pyfakefs by simply changing their base class from `:py:class`unittest.TestCase` to `:py:class`pyfakefs.fake_filesystem_unittest.TestCase`. """ import doctest import functools import inspect import linecache import shutil import sys import tempfile import tokenize import unittest import warnings from pyfakefs.deprecator import Deprecator from pyfakefs.fake_filesystem import set_uid, set_gid, reset_ids, PatchMode from pyfakefs.helpers import IS_PYPY from pyfakefs.patched_packages import ( get_modules_to_patch, get_classes_to_patch, get_fake_module_classes ) try: from importlib.machinery import ModuleSpec except ImportError: ModuleSpec = object from importlib import reload from pyfakefs import fake_filesystem from pyfakefs import fake_filesystem_shutil from pyfakefs import fake_pathlib from pyfakefs import mox3_stubout from pyfakefs.extra_packages import pathlib, pathlib2, use_scandir if use_scandir: from pyfakefs import fake_scandir OS_MODULE = 'nt' if sys.platform == 'win32' else 'posix' PATH_MODULE = 'ntpath' if sys.platform == 'win32' else 'posixpath' def patchfs(_func=None, *, additional_skip_names=None, modules_to_reload=None, modules_to_patch=None, allow_root_user=True, use_known_patches=True, patch_open_code=PatchMode.OFF, patch_default_args=False, use_cache=True): """Convenience decorator to use patcher with additional parameters in a test function. Usage:: @patchfs def test_my_function(fake_fs): fake_fs.create_file('foo') @patchfs(allow_root_user=False) def test_with_patcher_args(fs): os.makedirs('foo/bar') """ def wrap_patchfs(f): @functools.wraps(f) def wrapped(*args, **kwargs): with Patcher( additional_skip_names=additional_skip_names, modules_to_reload=modules_to_reload, modules_to_patch=modules_to_patch, allow_root_user=allow_root_user, use_known_patches=use_known_patches, patch_open_code=patch_open_code, patch_default_args=patch_default_args, use_cache=use_cache) as p: args = list(args) args.append(p.fs) return f(*args, **kwargs) return wrapped if _func: if not callable(_func): raise TypeError( "Decorator argument is not a function.\n" "Did you mean `@patchfs(additional_skip_names=...)`?" ) if hasattr(_func, 'patchings'): _func.nr_patches = len(_func.patchings) return wrap_patchfs(_func) return wrap_patchfs def load_doctests( loader, tests, ignore, module, additional_skip_names=None, modules_to_reload=None, modules_to_patch=None, allow_root_user=True, use_known_patches=True, patch_open_code=PatchMode.OFF, patch_default_args=False): # pylint: disable=unused-argument """Load the doctest tests for the specified module into unittest. Args: loader, tests, ignore : arguments passed in from `load_tests()` module: module under test remaining args: see :py:class:`TestCase` for an explanation File `example_test.py` in the pyfakefs release provides a usage example. """ _patcher = Patcher(additional_skip_names=additional_skip_names, modules_to_reload=modules_to_reload, modules_to_patch=modules_to_patch, allow_root_user=allow_root_user, use_known_patches=use_known_patches, patch_open_code=patch_open_code, patch_default_args=patch_default_args) globs = _patcher.replace_globs(vars(module)) tests.addTests(doctest.DocTestSuite(module, globs=globs, setUp=_patcher.setUp, tearDown=_patcher.tearDown)) return tests class TestCaseMixin: """Test case mixin that automatically replaces file-system related modules by fake implementations. Attributes: additional_skip_names: names of modules inside of which no module replacement shall be performed, in addition to the names in :py:attr:`fake_filesystem_unittest.Patcher.SKIPNAMES`. Instead of the module names, the modules themselves may be used. modules_to_reload: A list of modules that need to be reloaded to be patched dynamically; may be needed if the module imports file system modules under an alias .. caution:: Reloading modules may have unwanted side effects. modules_to_patch: A dictionary of fake modules mapped to the fully qualified patched module names. Can be used to add patching of modules not provided by `pyfakefs`. If you specify some of these attributes here and you have DocTests, consider also specifying the same arguments to :py:func:`load_doctests`. Example usage in derived test classes:: from unittest import TestCase from fake_filesystem_unittest import TestCaseMixin class MyTestCase(TestCase, TestCaseMixin): def __init__(self, methodName='runTest'): super(MyTestCase, self).__init__( methodName=methodName, additional_skip_names=['posixpath']) import sut class AnotherTestCase(TestCase, TestCaseMixin): def __init__(self, methodName='runTest'): super(MyTestCase, self).__init__( methodName=methodName, modules_to_reload=[sut]) """ additional_skip_names = None modules_to_reload = None modules_to_patch = None @property def fs(self): return self._stubber.fs def setUpPyfakefs(self, additional_skip_names=None, modules_to_reload=None, modules_to_patch=None, allow_root_user=True, use_known_patches=True, patch_open_code=PatchMode.OFF, patch_default_args=False, use_cache=True): """Bind the file-related modules to the :py:class:`pyfakefs` fake file system instead of the real file system. Also bind the fake `open()` function. Invoke this at the beginning of the `setUp()` method in your unit test class. For the arguments, see the `TestCaseMixin` attribute description. If any of the arguments is not None, it overwrites the settings for the current test case. Settings the arguments here may be a more convenient way to adapt the setting than overwriting `__init__()`. """ if additional_skip_names is None: additional_skip_names = self.additional_skip_names if modules_to_reload is None: modules_to_reload = self.modules_to_reload if modules_to_patch is None: modules_to_patch = self.modules_to_patch self._stubber = Patcher( additional_skip_names=additional_skip_names, modules_to_reload=modules_to_reload, modules_to_patch=modules_to_patch, allow_root_user=allow_root_user, use_known_patches=use_known_patches, patch_open_code=patch_open_code, patch_default_args=patch_default_args, use_cache=use_cache ) self._stubber.setUp() self.addCleanup(self._stubber.tearDown) def pause(self): """Pause the patching of the file system modules until `resume` is called. After that call, all file system calls are executed in the real file system. Calling pause() twice is silently ignored. """ self._stubber.pause() def resume(self): """Resume the patching of the file system modules if `pause` has been called before. After that call, all file system calls are executed in the fake file system. Does nothing if patching is not paused. """ self._stubber.resume() class TestCase(unittest.TestCase, TestCaseMixin): """Test case class that automatically replaces file-system related modules by fake implementations. Inherits :py:class:`TestCaseMixin`. The arguments are explained in :py:class:`TestCaseMixin`. """ def __init__(self, methodName='runTest', additional_skip_names=None, modules_to_reload=None, modules_to_patch=None): """Creates the test class instance and the patcher used to stub out file system related modules. Args: methodName: The name of the test method (same as in unittest.TestCase) """ super(TestCase, self).__init__(methodName) self.additional_skip_names = additional_skip_names self.modules_to_reload = modules_to_reload self.modules_to_patch = modules_to_patch @Deprecator('add_real_file') def copyRealFile(self, real_file_path, fake_file_path=None, create_missing_dirs=True): """Add the file `real_file_path` in the real file system to the same path in the fake file system. **This method is deprecated** in favor of :py:meth:`FakeFilesystem..add_real_file`. `copyRealFile()` is retained with limited functionality for backward compatibility only. Args: real_file_path: Path to the file in both the real and fake file systems fake_file_path: Deprecated. Use the default, which is `real_file_path`. If a value other than `real_file_path` is specified, a `ValueError` exception will be raised. create_missing_dirs: Deprecated. Use the default, which creates missing directories in the fake file system. If `False` is specified, a `ValueError` exception is raised. Returns: The newly created FakeFile object. Raises: OSError: If the file already exists in the fake file system. ValueError: If deprecated argument values are specified. See: :py:meth:`FakeFileSystem.add_real_file` """ if fake_file_path is not None and real_file_path != fake_file_path: raise ValueError("CopyRealFile() is deprecated and no longer " "supports different real and fake file paths") if not create_missing_dirs: raise ValueError("CopyRealFile() is deprecated and no longer " "supports NOT creating missing directories") return self._stubber.fs.add_real_file(real_file_path, read_only=False) @DeprecationWarning def tearDownPyfakefs(self): """This method is deprecated and exists only for backward compatibility. It does nothing. """ pass class Patcher: """ Instantiate a stub creator to bind and un-bind the file-related modules to the :py:mod:`pyfakefs` fake modules. The arguments are explained in :py:class:`TestCaseMixin`. :py:class:`Patcher` is used in :py:class:`TestCaseMixin`. :py:class:`Patcher` also works as a context manager for other tests:: with Patcher(): doStuff() """ '''Stub nothing that is imported within these modules. `sys` is included to prevent `sys.path` from being stubbed with the fake `os.path`. The `pytest` and `py` modules are used by pytest and have to access the real file system. The `linecache` module is used to read the test file in case of test failure to get traceback information before test tear down. In order to make sure that reading the test file is not faked, we skip faking the module. We also have to set back the cached open function in tokenize. ''' SKIPMODULES = { None, fake_filesystem, fake_filesystem_shutil, sys, linecache, tokenize } # caches all modules that do not have file system modules or function # to speed up _find_modules CACHED_MODULES = set() FS_MODULES = {} FS_FUNCTIONS = {} FS_DEFARGS = [] SKIPPED_FS_MODULES = {} assert None in SKIPMODULES, ("sys.modules contains 'None' values;" " must skip them.") IS_WINDOWS = sys.platform in ('win32', 'cygwin') SKIPNAMES = {'os', 'path', 'io', 'genericpath', OS_MODULE, PATH_MODULE} # hold values from last call - if changed, the cache has to be invalidated PATCHED_MODULE_NAMES = {} ADDITIONAL_SKIP_NAMES = set() PATCH_DEFAULT_ARGS = False def __init__(self, additional_skip_names=None, modules_to_reload=None, modules_to_patch=None, allow_root_user=True, use_known_patches=True, patch_open_code=PatchMode.OFF, patch_default_args=False, use_cache=True): """ Args: additional_skip_names: names of modules inside of which no module replacement shall be performed, in addition to the names in :py:attr:`fake_filesystem_unittest.Patcher.SKIPNAMES`. Instead of the module names, the modules themselves may be used. modules_to_reload: A list of modules that need to be reloaded to be patched dynamically; may be needed if the module imports file system modules under an alias .. caution:: Reloading modules may have unwanted side effects. modules_to_patch: A dictionary of fake modules mapped to the fully qualified patched module names. Can be used to add patching of modules not provided by `pyfakefs`. allow_root_user: If True (default), if the test is run as root user, the user in the fake file system is also considered a root user, otherwise it is always considered a regular user. use_known_patches: If True (the default), some patches for commonly used packages are applied which make them usable with pyfakefs. patch_open_code: If True, `io.open_code` is patched. The default is not to patch it, as it mostly is used to load compiled modules that are not in the fake file system. patch_default_args: If True, default arguments are checked for file system functions, which are patched. This check is expansive, so it is off by default. use_cache: If True (default), patched and non-patched modules are cached between tests for performance reasons. As this is a new feature, this argument allows to turn it off in case it causes any problems. """ if not allow_root_user: # set non-root IDs even if the real user is root set_uid(1) set_gid(1) self._skip_names = self.SKIPNAMES.copy() # save the original open function for use in pytest plugin self.original_open = open self.patch_open_code = patch_open_code if additional_skip_names is not None: skip_names = [m.__name__ if inspect.ismodule(m) else m for m in additional_skip_names] self._skip_names.update(skip_names) self._fake_module_classes = {} self._unfaked_module_classes = {} self._class_modules = {} self._init_fake_module_classes() # reload tempfile under posix to patch default argument self.modules_to_reload = [] if sys.platform == 'win32' else [tempfile] if modules_to_reload is not None: self.modules_to_reload.extend(modules_to_reload) self.patch_default_args = patch_default_args self.use_cache = use_cache if use_known_patches: modules_to_patch = modules_to_patch or {} modules_to_patch.update(get_modules_to_patch()) self._class_modules.update(get_classes_to_patch()) self._fake_module_classes.update(get_fake_module_classes()) if modules_to_patch is not None: for name, fake_module in modules_to_patch.items(): self._fake_module_classes[name] = fake_module patched_module_names = set(modules_to_patch) clear_cache = not use_cache if use_cache: if patched_module_names != self.PATCHED_MODULE_NAMES: self.__class__.PATCHED_MODULE_NAMES = patched_module_names clear_cache = True if self._skip_names != self.ADDITIONAL_SKIP_NAMES: self.__class__.ADDITIONAL_SKIP_NAMES = self._skip_names clear_cache = True if patch_default_args != self.PATCH_DEFAULT_ARGS: self.__class__.PATCH_DEFAULT_ARGS = patch_default_args clear_cache = True if clear_cache: self.clear_cache() self._fake_module_functions = {} self._init_fake_module_functions() # Attributes set by _refresh() self._stubs = None self.fs = None self.fake_modules = {} self.unfaked_modules = {} # _isStale is set by tearDown(), reset by _refresh() self._isStale = True self._dyn_patcher = None self._patching = False def clear_cache(self): """Clear the module cache.""" self.__class__.CACHED_MODULES = set() self.__class__.FS_MODULES = {} self.__class__.FS_FUNCTIONS = {} self.__class__.FS_DEFARGS = [] self.__class__.SKIPPED_FS_MODULES = {} def _init_fake_module_classes(self): # IMPORTANT TESTING NOTE: Whenever you add a new module below, test # it by adding an attribute in fixtures/module_with_attributes.py # and a test in fake_filesystem_unittest_test.py, class # TestAttributesWithFakeModuleNames. self._fake_module_classes = { 'os': fake_filesystem.FakeOsModule, 'shutil': fake_filesystem_shutil.FakeShutilModule, 'io': fake_filesystem.FakeIoModule, } if IS_PYPY: # in PyPy io.open, the module is referenced as _io self._fake_module_classes['_io'] = fake_filesystem.FakeIoModule # class modules maps class names against a list of modules they can # be contained in - this allows for alternative modules like # `pathlib` and `pathlib2` self._class_modules['Path'] = [] if pathlib: self._fake_module_classes[ 'pathlib'] = fake_pathlib.FakePathlibModule self._class_modules['Path'].append('pathlib') self._unfaked_module_classes[ 'pathlib'] = fake_pathlib.RealPathlibModule if pathlib2: self._fake_module_classes[ 'pathlib2'] = fake_pathlib.FakePathlibModule self._class_modules['Path'].append('pathlib2') self._unfaked_module_classes[ 'pathlib2'] = fake_pathlib.RealPathlibModule self._fake_module_classes[ 'Path'] = fake_pathlib.FakePathlibPathModule self._unfaked_module_classes[ 'Path'] = fake_pathlib.RealPathlibPathModule if use_scandir: self._fake_module_classes[ 'scandir'] = fake_scandir.FakeScanDirModule def _init_fake_module_functions(self): # handle patching function imported separately like # `from os import stat` # each patched function name has to be looked up separately for mod_name, fake_module in self._fake_module_classes.items(): if (hasattr(fake_module, 'dir') and inspect.isfunction(fake_module.dir)): for fct_name in fake_module.dir(): module_attr = (getattr(fake_module, fct_name), mod_name) self._fake_module_functions.setdefault( fct_name, {})[mod_name] = module_attr if mod_name == 'os': self._fake_module_functions.setdefault( fct_name, {})[OS_MODULE] = module_attr # special handling for functions in os.path fake_module = fake_filesystem.FakePathModule for fct_name in fake_module.dir(): module_attr = (getattr(fake_module, fct_name), PATH_MODULE) self._fake_module_functions.setdefault( fct_name, {})['genericpath'] = module_attr self._fake_module_functions.setdefault( fct_name, {})[PATH_MODULE] = module_attr def __enter__(self): """Context manager for usage outside of fake_filesystem_unittest.TestCase. Ensure that all patched modules are removed in case of an unhandled exception. """ self.setUp() return self def __exit__(self, exc_type, exc_val, exc_tb): self.tearDown() def _is_fs_module(self, mod, name, module_names): try: # check for __name__ first and ignore the AttributeException # if it does not exist - avoids calling expansive ismodule if mod.__name__ in module_names and inspect.ismodule(mod): return True except Exception: pass try: if (name in self._class_modules and mod.__module__ in self._class_modules[name]): return inspect.isclass(mod) except Exception: # handle AttributeError and any other exception possibly triggered # by side effects of inspect methods return False def _is_fs_function(self, fct): try: # check for __name__ first and ignore the AttributeException # if it does not exist - avoids calling expansive inspect # methods in most cases return (fct.__name__ in self._fake_module_functions and fct.__module__ in self._fake_module_functions[ fct.__name__] and (inspect.isfunction(fct) or inspect.isbuiltin(fct))) except Exception: # handle AttributeError and any other exception possibly triggered # by side effects of inspect methods return False def _def_values(self, item): """Find default arguments that are file-system functions to be patched in top-level functions and members of top-level classes.""" # check for module-level functions try: if item.__defaults__ and inspect.isfunction(item): for i, d in enumerate(item.__defaults__): if self._is_fs_function(d): yield item, i, d except Exception: pass try: if inspect.isclass(item): # check for methods in class # (nested classes are ignored for now) # inspect.getmembers is very expansive! for m in inspect.getmembers(item, predicate=inspect.isfunction): m = m[1] if m.__defaults__: for i, d in enumerate(m.__defaults__): if self._is_fs_function(d): yield m, i, d except Exception: # Ignore any exception, examples: # ImportError: No module named '_gdbm' # _DontDoThat() (see #523) pass def _find_def_values(self, module_items): for _, fct in module_items: for f, i, d in self._def_values(fct): self.__class__.FS_DEFARGS.append((f, i, d)) def _find_modules(self): """Find and cache all modules that import file system modules. Later, `setUp()` will stub these with the fake file system modules. """ module_names = list(self._fake_module_classes.keys()) + [PATH_MODULE] for name, module in list(sys.modules.items()): try: if (self.use_cache and module in self.CACHED_MODULES or module in self.SKIPMODULES or not inspect.ismodule(module)): continue except Exception: # workaround for some py (part of pytest) versions # where py.error has no __name__ attribute # see https://github.com/pytest-dev/py/issues/73 # and any other exception triggered by inspect.ismodule if self.use_cache: self.__class__.CACHED_MODULES.add(module) continue skipped = (any([sn.startswith(module.__name__) for sn in self._skip_names])) module_items = module.__dict__.copy().items() modules = {name: mod for name, mod in module_items if self._is_fs_module(mod, name, module_names)} if skipped: for name, mod in modules.items(): self.__class__.SKIPPED_FS_MODULES.setdefault( name, set()).add((module, mod.__name__)) continue for name, mod in modules.items(): self.__class__.FS_MODULES.setdefault(name, set()).add( (module, mod.__name__)) functions = {name: fct for name, fct in module_items if self._is_fs_function(fct)} for name, fct in functions.items(): self.__class__.FS_FUNCTIONS.setdefault( (name, fct.__name__, fct.__module__), set()).add(module) # find default arguments that are file system functions if self.patch_default_args: self._find_def_values(module_items) if self.use_cache: self.__class__.CACHED_MODULES.add(module) def _refresh(self): """Renew the fake file system and set the _isStale flag to `False`.""" if self._stubs is not None: self._stubs.smart_unset_all() self._stubs = mox3_stubout.StubOutForTesting() self.fs = fake_filesystem.FakeFilesystem(patcher=self) self.fs.patch_open_code = self.patch_open_code for name in self._fake_module_classes: self.fake_modules[name] = self._fake_module_classes[name](self.fs) if hasattr(self.fake_modules[name], 'skip_names'): self.fake_modules[name].skip_names = self._skip_names self.fake_modules[PATH_MODULE] = self.fake_modules['os'].path for name in self._unfaked_module_classes: self.unfaked_modules[name] = self._unfaked_module_classes[name]() self._isStale = False def setUp(self, doctester=None): """Bind the file-related modules to the :py:mod:`pyfakefs` fake modules real ones. Also bind the fake `file()` and `open()` functions. """ self.has_fcopy_file = (sys.platform == 'darwin' and hasattr(shutil, '_HAS_FCOPYFILE') and shutil._HAS_FCOPYFILE) if self.has_fcopy_file: shutil._HAS_FCOPYFILE = False temp_dir = tempfile.gettempdir() with warnings.catch_warnings(): # ignore deprecation warnings, see #542 warnings.filterwarnings( 'ignore', category=DeprecationWarning ) self._find_modules() self._refresh() if doctester is not None: doctester.globs = self.replace_globs(doctester.globs) self.start_patching() linecache.open = self.original_open tokenize._builtin_open = self.original_open # the temp directory is assumed to exist at least in `tempfile1`, # so we create it here for convenience self.fs.create_dir(temp_dir) def start_patching(self): if not self._patching: self._patching = True self.patch_modules() self.patch_functions() self.patch_defaults() self._dyn_patcher = DynamicPatcher(self) sys.meta_path.insert(0, self._dyn_patcher) for module in self.modules_to_reload: if module.__name__ in sys.modules: reload(module) def patch_functions(self): for (name, ft_name, ft_mod), modules in self.FS_FUNCTIONS.items(): method, mod_name = self._fake_module_functions[ft_name][ft_mod] fake_module = self.fake_modules[mod_name] attr = method.__get__(fake_module, fake_module.__class__) for module in modules: self._stubs.smart_set(module, name, attr) def patch_modules(self): for name, modules in self.FS_MODULES.items(): for module, attr in modules: self._stubs.smart_set( module, name, self.fake_modules[attr]) for name, modules in self.SKIPPED_FS_MODULES.items(): for module, attr in modules: if attr in self.unfaked_modules: self._stubs.smart_set( module, name, self.unfaked_modules[attr]) def patch_defaults(self): for (fct, idx, ft) in self.FS_DEFARGS: method, mod_name = self._fake_module_functions[ ft.__name__][ft.__module__] fake_module = self.fake_modules[mod_name] attr = method.__get__(fake_module, fake_module.__class__) new_defaults = [] for i, d in enumerate(fct.__defaults__): if i == idx: new_defaults.append(attr) else: new_defaults.append(d) fct.__defaults__ = tuple(new_defaults) def replace_globs(self, globs_): globs = globs_.copy() if self._isStale: self._refresh() for name in self._fake_module_classes: if name in globs: globs[name] = self._fake_module_classes[name](self.fs) return globs def tearDown(self, doctester=None): """Clear the fake filesystem bindings created by `setUp()`.""" self.stop_patching() if self.has_fcopy_file: shutil._HAS_FCOPYFILE = True reset_ids() def stop_patching(self): if self._patching: self._isStale = True self._patching = False self._stubs.smart_unset_all() self.unset_defaults() self._dyn_patcher.cleanup() sys.meta_path.pop(0) def unset_defaults(self): for (fct, idx, ft) in self.FS_DEFARGS: new_defaults = [] for i, d in enumerate(fct.__defaults__): if i == idx: new_defaults.append(ft) else: new_defaults.append(d) fct.__defaults__ = tuple(new_defaults) # self._def_functions = [] def pause(self): """Pause the patching of the file system modules until `resume` is called. After that call, all file system calls are executed in the real file system. Calling pause() twice is silently ignored. """ self.stop_patching() def resume(self): """Resume the patching of the file system modules if `pause` has been called before. After that call, all file system calls are executed in the fake file system. Does nothing if patching is not paused. """ self.start_patching() class Pause: """Simple context manager that allows to pause/resume patching the filesystem. Patching is paused in the context manager, and resumed after going out of it's scope. """ def __init__(self, caller): """Initializes the context manager with the fake filesystem. Args: caller: either the FakeFilesystem instance, the Patcher instance or the pyfakefs test case. """ if isinstance(caller, (Patcher, TestCaseMixin)): self._fs = caller.fs elif isinstance(caller, fake_filesystem.FakeFilesystem): self._fs = caller else: raise ValueError('Invalid argument - should be of type ' '"fake_filesystem_unittest.Patcher", ' '"fake_filesystem_unittest.TestCase" ' 'or "fake_filesystem.FakeFilesystem"') def __enter__(self): self._fs.pause() return self._fs def __exit__(self, *args): return self._fs.resume() class DynamicPatcher: """A file loader that replaces file system related modules by their fake implementation if they are loaded after calling `setUpPyfakefs()`. Implements the protocol needed for import hooks. """ def __init__(self, patcher): self._patcher = patcher self.sysmodules = {} self.modules = self._patcher.fake_modules self._loaded_module_names = set() # remove all modules that have to be patched from `sys.modules`, # otherwise the find_... methods will not be called for name in self.modules: if self.needs_patch(name) and name in sys.modules: self.sysmodules[name] = sys.modules[name] del sys.modules[name] for name, module in self.modules.items(): sys.modules[name] = module def cleanup(self): for module in self.sysmodules: sys.modules[module] = self.sysmodules[module] for module in self._patcher.modules_to_reload: if module.__name__ in sys.modules: reload(module) reloaded_module_names = [module.__name__ for module in self._patcher.modules_to_reload] # Dereference all modules loaded during the test so they will reload on # the next use, ensuring that no faked modules are referenced after the # test. for name in self._loaded_module_names: if name in sys.modules and name not in reloaded_module_names: del sys.modules[name] def needs_patch(self, name): """Check if the module with the given name shall be replaced.""" if name not in self.modules: self._loaded_module_names.add(name) return False if (name in sys.modules and type(sys.modules[name]) == self.modules[name]): return False return True def find_spec(self, fullname, path, target=None): """Module finder for Python 3.""" if self.needs_patch(fullname): return ModuleSpec(fullname, self) def load_module(self, fullname): """Replaces the module by its fake implementation.""" sys.modules[fullname] = self.modules[fullname] return self.modules[fullname]