[Telemetry] Add pyfakefs to telemetry/third_party

tools/telemetry/third_party/pyfakefs/pyfakefs/example.py

Index: tools/telemetry/third_party/pyfakefs/pyfakefs/example.py
diff --git a/tools/telemetry/third_party/pyfakefs/pyfakefs/example.py b/tools/telemetry/third_party/pyfakefs/pyfakefs/example.py
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+++ b/tools/telemetry/third_party/pyfakefs/pyfakefs/example.py
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+# Copyright 2014 Altera Corporation. All Rights Reserved.
+# Author: 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.
+
+"""
+Example module that is tested in :py:class`pyfakefs.example_test.TestExample`.
+This demonstrates the usage of the
+:py:class`pyfakefs.fake_filesystem_unittest.TestCase` base class.
+
+The modules related to file handling are bound to the respective fake modules:
+
+>>> os     #doctest: +ELLIPSIS 
+<fake_filesystem.FakeOsModule object...>
+>>> os.path     #doctest: +ELLIPSIS
+<fake_filesystem.FakePathModule object...>
+>>> glob     #doctest: +ELLIPSIS
+<fake_filesystem_glob.FakeGlobModule object...>
+>>> shutil     #doctest: +ELLIPSIS
+<fake_filesystem_shutil.FakeShutilModule object...>
+
+The `file()` and `open()` built-ins are bound to the fake `open()`:
+
+>>> file     #doctest: +ELLIPSIS
+<fake_filesystem.FakeFileOpen object...>
+>>> open     #doctest: +ELLIPSIS
+<fake_filesystem.FakeFileOpen object...>
+"""
+
+import os
+import glob
+import shutil
+
+def create_file(path):
+    '''Create the specified file and add some content to it.  Use the `open()`
+    built in function.
+    
+    For example, the following file operations occur in the fake file system.
+    In the real file system, we would not even have permission to write `/test`:
+    
+    >>> os.path.isdir('/test')
+    False
+    >>> os.mkdir('/test')
+    >>> os.path.isdir('/test')
+    True
+    >>> os.path.exists('/test/file.txt')
+    False
+    >>> create_file('/test/file.txt')
+    >>> os.path.exists('/test/file.txt')
+    True
+    >>> with open('/test/file.txt') as f:
+    ...     f.readlines()
+    ["This is test file '/test/file.txt'.\\n", 'It was created using the open() function.\\n']
+    '''
+    with open(path, 'w') as f:
+        f.write("This is test file '{}'.\n".format(path))
+        f.write("It was created using the open() function.\n")
+
+def delete_file(path):
+    '''Delete the specified file.
+    
+    For example:
+        
+    >>> os.mkdir('/test')
+    >>> os.path.exists('/test/file.txt')
+    False
+    >>> create_file('/test/file.txt')
+    >>> os.path.exists('/test/file.txt')
+    True
+    >>> delete_file('/test/file.txt')
+    >>> os.path.exists('/test/file.txt')
+    False
+    '''
+    os.remove(path)
+    
+def path_exists(path):
+    '''Return True if the specified file exists.
+    
+    For example:
+        
+    >>> path_exists('/test')
+    False
+    >>> os.mkdir('/test')
+    >>> path_exists('/test')
+    True
+    >>>
+    >>> path_exists('/test/file.txt')
+    False
+    >>> create_file('/test/file.txt')
+    >>> path_exists('/test/file.txt')
+    True
+    '''
+    return os.path.exists(path)
+
+def get_glob(glob_path):
+    '''Return the list of paths matching the specified glob expression.
+    
+    For example:
+    
+    >>> os.mkdir('/test')
+    >>> create_file('/test/file1.txt')
+    >>> create_file('/test/file2.txt')
+    >>> get_glob('/test/file*.txt')
+    ['/test/file1.txt', '/test/file2.txt']
+    '''
+    return glob.glob(glob_path)
+
+def rm_tree(path):
+    '''Delete the specified file hierarchy.'''
+    shutil.rmtree(path)