__init__.py 文件源码

def change_cwd(path, quiet=False):
    """Return a context manager that changes the current working directory.

    Arguments:

      path: the directory to use as the temporary current working directory.

      quiet: if False (the default), the context manager raises an exception
        on error.  Otherwise, it issues only a warning and keeps the current
        working directory the same.

    """
    saved_dir = os.getcwd()
    try:
        os.chdir(path)
    except OSError:
        if not quiet:
            raise
        warnings.warn('tests may fail, unable to change CWD to: ' + path,
                      RuntimeWarning, stacklevel=3)
    try:
        yield os.getcwd()
    finally:
        os.chdir(saved_dir)