[Telemetry] Add pyfakefs to telemetry/third_party

tools/telemetry/third_party/pyfakefs/pyfakefs/fake_filesystem_unittest.py

+# Copyright 2014 Altera Corporation. All Rights Reserved.
+# Author: John McGehee
+#
+# Copyright 2014 John McGehee.  All Rights Reserved.
+#
+# 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.
+
+"""A base class for unit tests using the :py:class:`pyfakefs` module.
+
+This class searches `sys.modules` for modules that import the `os`, `glob`,
+`shutil`, and `tempfile` modules.
+
+The `setUp()` method binds these modules to the corresponding fake
+modules from `pyfakefs`.  Further, the built in functions `file()` and
+`open()` are bound to fake functions.
+
+The `tearDownPyfakefs()` method returns the module bindings to their original
+state.
+
+It is expected that `setUp()` be invoked at the beginning of the derived
+class' `setUp()` method, and `tearDownPyfakefs()` be invoked at the end of the
+derived class' `tearDown()` method.
+
+During the test, everything uses the fake file system and modules.  This means
+that even in your test, you can use familiar functions like `open()` and
+`os.makedirs()` to manipulate the fake file system.
+
+This also means existing unit tests that use the real file system can be
+retro-fitted to use `pyfakefs` by simply changing their base class from
+`:py:class`unittest.TestCase` to
+`:py:class`pyfakefs.fake_filesystem_unittest.TestCase`.
+"""
+
+import sys
+import unittest
+import doctest
+import inspect
+import fake_filesystem
+import fake_filesystem_glob
+import fake_filesystem_shutil
+import fake_tempfile
+
+import mock
+
+def load_doctests(loader, tests, ignore, module):
+    '''Load the doctest tests for the specified module into unittest.'''
+    _patcher = _Patcher()
+    globs = _patcher.replaceGlobs(vars(module))
+    tests.addTests(doctest.DocTestSuite(module,
+                                        globs=globs,
+                                        setUp=_patcher.setUp,
+                                        tearDown=_patcher.tearDown))
+    return tests
+
+
+class TestCase(unittest.TestCase):
+    def __init__(self, methodName='runTest'):
+        super(TestCase, self).__init__(methodName)
+        self._stubber = _Patcher()
+        
+    @property
+    def fs(self):
+        return self._stubber.fs
+    
+    @property
+    def patches(self):
+        return self._stubber.patches
+        
+    def setUpPyfakefs(self):
+        '''Bind the file-related modules to the :py:class:`pyfakefs` fake file
+        system instead of the real file system.  Also bind the fake `file()` and
+        `open()` functions.
+        
+        Invoke this at the beginning of the `setUp()` method in your unit test
+        class.
+        '''
+        self._stubber.setUp()
+        self.addCleanup(self._stubber.tearDown)
+
+    
+    def tearDownPyfakefs(self):
+        ''':meth:`pyfakefs.fake_filesystem_unittest.setUpPyfakefs` registers the
+        tear down procedure using :meth:unittest.TestCase.addCleanup`.  Thus this
+        method is deprecated, and remains just for backward compatibility.
+        '''
+        pass
+
+class _Patcher(object):
+    '''
+    Instantiate a stub creator to bind and un-bind the file-related modules to
+    the :py:module:`pyfakefs` fake modules.
+    '''
+    SKIPMODULES = set([None, fake_filesystem, fake_filesystem_glob,
+                      fake_filesystem_shutil, fake_tempfile, unittest,
+                      sys])
+    '''Stub nothing that is imported within these modules.
+    `sys` is included to prevent `sys.path` from being stubbed with the fake
+    `os.path`.
+    '''
+    assert None in SKIPMODULES, "sys.modules contains 'None' values; must skip them."
+    
+    SKIPNAMES = set(['os', 'glob', 'path', 'shutil', 'tempfile'])
+        
+    def __init__(self):
+        # Attributes set by _findModules()
+        self._osModuleNames = None
+        self._globModuleNames = None
+        self._pathModuleNames = None
+        self._shutilModuleNames = None
+        self._tempfileModuleNames = None
+        self._findModules()
+        assert None not in vars(self).values(), \
+                "_findModules() missed the initialization of an instance variable"
+        
+        # Attributes set by _refresh()
+        self.fs = None
+        self.fake_os = None
+        self.fake_glob = None
+        self.fake_path = None
+        self.fake_shutil = None
+        self.fake_tempfile_ = None
+        self.fake_open = None
+        # _isStale is set by tearDown(), reset by _refresh()
+        self._isStale = True
+        self._refresh()
+        assert None not in vars(self).values(), \
+                "_refresh() missed the initialization of an instance variable"
+        assert self._isStale == False, "_refresh() did not reset _isStale"
+        
+    def _findModules(self):
+        '''Find and cache all modules that import file system modules.
+        Later, `setUp()` will stub these with the fake file system
+        modules.
+        '''
+        self._osModuleNames = set()
+        self._globModuleNames = set()
+        self._pathModuleNames = set()
+        self._shutilModuleNames = set()
+        self._tempfileModuleNames = set()
+        for name, module in set(sys.modules.items()):
+            if module in self.SKIPMODULES or name in self.SKIPNAMES or (not inspect.ismodule(module)):
+                continue
+            if 'os' in module.__dict__ and inspect.ismodule(module.__dict__['os']):
+                self._osModuleNames.add(name + '.os')
+            if 'glob' in module.__dict__:
+                self._globModuleNames.add(name + '.glob')
+            if 'path' in module.__dict__:
+                self._pathModuleNames.add(name + '.path')
+            if 'shutil' in module.__dict__:
+                self._shutilModuleNames.add(name + '.shutil')
+            if 'tempfile' in module.__dict__:
+                self._tempfileModuleNames.add(name + '.tempfile')
+            
+    def _refresh(self):
+        '''Renew the fake file system and set the _isStale flag to `False`.'''
+        mock.patch.stopall()
+        
+        self.fs = fake_filesystem.FakeFilesystem()
+        self.fake_os = fake_filesystem.FakeOsModule(self.fs)
+        self.fake_glob = fake_filesystem_glob.FakeGlobModule(self.fs)
+        self.fake_path = self.fake_os.path
+        self.fake_shutil = fake_filesystem_shutil.FakeShutilModule(self.fs)
+        self.fake_tempfile_ = fake_tempfile.FakeTempfileModule(self.fs)
+        self.fake_open = fake_filesystem.FakeFileOpen(self.fs)
+
+        self._isStale = False
+
+    def setUp(self, doctester=None):
+        '''Bind the file-related modules to the :py:module:`pyfakefs` fake
+        modules real ones.  Also bind the fake `file()` and `open()` functions.
+        '''
+        if self._isStale:
+            self._refresh()
+        
+        if doctester is not None:
+            doctester.globs = self.replaceGlobs(doctester.globs)
+            
+        def startPatch(self, realModuleName, fakeModule):
+            if realModuleName == 'unittest.main.os':
+                # Known issue with unittest.main resolving to unittest.main.TestProgram
+                # See mock module bug 250, https://code.google.com/p/mock/issues/detail?id=250.
+                return
+            patch = mock.patch(realModuleName, new=fakeModule)
+            try:
+                patch.start()
+            except:
+                target, attribute = realModuleName.rsplit('.', 1)
+                print("Warning: Could not patch '{}' on module '{}' because '{}' resolves to {}".format(attribute, target, target, patch.getter()))
+                print("         See mock module bug 250, https://code.google.com/p/mock/issues/detail?id=250")
+            
+        startPatch(self, '__builtin__.file', self.fake_open)
+        startPatch(self, '__builtin__.open', self.fake_open)
+
+        for module in self._osModuleNames:
+            startPatch(self, module, self.fake_os)
+        for module in self._globModuleNames:
+            startPatch(self, module, self.fake_glob)
+        for module in self._pathModuleNames:
+            startPatch(self, module, self.fake_path)
+        for module in self._shutilModuleNames:
+            startPatch(self, module, self.fake_shutil)
+        for module in self._tempfileModuleNames:
+            startPatch(self, module, self.fake_tempfile_)
+                    
+    def replaceGlobs(self, globs_):
+        globs = globs_.copy()
+        if self._isStale:
+            self._refresh()
+        if 'os' in globs:
+            globs['os'] = fake_filesystem.FakeOsModule(self.fs)
+        if 'glob' in globs:
+            globs['glob'] = fake_filesystem_glob.FakeGlobModule(self.fs)
+        if 'path' in globs:
+            fake_os = globs['os'] if 'os' in globs \
+                else fake_filesystem.FakeOsModule(self.fs)
+            globs['path'] = fake_os.path
+        if 'shutil' in globs:
+            globs['shutil'] = fake_filesystem_shutil.FakeShutilModule(self.fs)
+        if 'tempfile' in globs:
+            globs['tempfile'] = fake_tempfile.FakeTempfileModule(self.fs)
+        return globs
+    
+    def tearDown(self, doctester=None):
+        '''Clear the fake filesystem bindings created by `setUp()`.'''
+        self._isStale = True
+        mock.patch.stopall()