testutils.py 文件源码

def __enter__(self):
        assert self._original_fds is None, 'You can only use this object once'

        # Save the original FDs and file objects.
        # FIXME: How about stdin?
        self._original_fds = [(fd, os.dup(fd)) for fd in (1, 2)]
        self._old_stdout = sys.stdout
        self._old_stderr = sys.stderr

        # Redirect the Python file objects.
        throwaway_fileno, self._redirected_path = tempfile.mkstemp()
        # We need to reopen the file or Python and non-Python will have two different
        # positions in the file (and we can't build a file object from a fileno).
        os.close(throwaway_fileno)
        self._redirected_file = open(self._redirected_path, 'w')
        sys.stdout = self._redirected_file
        sys.stderr = self._redirected_file

        # Redirect the standard FDs.
        os.dup2(self._redirected_file.fileno(), 1)
        os.dup2(self._redirected_file.fileno(), 2)

        return self