Coverage for sparts/ctx : 100%

# Copyright (c) 2014, Facebook, Inc.  All rights reserved. 

# 

# This source code is licensed under the BSD-style license found in the 

# LICENSE file in the root directory of this source tree. An additional grant 

# of patent rights can be found in the PATENTS file in the same directory. 

# 

"""Module containing various helpful context managers.""" 

from __future__ import absolute_import 

from contextlib import contextmanager 

from sparts.fileutils import NamedTemporaryDirectory 

import copy 

import os.path 

import sys 

@contextmanager 

def tmpdir(*args, **kwargs): 

    """Create a NamedTemporaryDirectory "as" the str path""" 

    with NamedTemporaryDirectory() as d: 

        yield d.name 

@contextmanager 

def add_path(path, index=None): 

    """Temporarily add `path` to the PYTHONPATH. Not thread-safe. 

    If `index` is None, append to the end, otherwise, use `index` as specified 

    to `list.insert()`""" 

    if index is None: 

        sys.path.append(path) 

    else: 

        sys.path.insert(index, path) 

    try: 

        yield path 

    finally: 

        sys.path.remove(path) 

@contextmanager 

def chdir(path): 

    """Temporarily chdir to `path`.  Not thread-safe.""" 

    assert os.path.exists(path) 

    assert os.path.isdir(path) 

    old_path = os.getcwd() 

    os.chdir(path) 

    try: 

        yield 

    finally: 

        os.chdir(old_path) 

@contextmanager 

def module_snapshot(): 

    """Removes any new modules from the module cache after context exit""" 

    try: 

        modules = copy.copy(sys.modules) 

        yield 

    finally: 

        to_delete = [k for k in sys.modules if k not in modules] 

        for k in to_delete: 

            del sys.modules[k]