support.py 文件源码

def captured_output(stream_name):
    """Return a context manager used by captured_stdout/stdin/stderr
    that temporarily replaces the sys stream *stream_name* with a StringIO."""
    orig_stdout = getattr(sys, stream_name)
    setattr(sys, stream_name, StringIO())
    try:
        yield getattr(sys, stream_name)
    finally:
        setattr(sys, stream_name, orig_stdout)