demoweb/venv/lib/python3.7/site-packages/twisted/test/process_fds.py

"""Write to a handful of file descriptors, to test the childFDs= argument of
reactor.spawnProcess()
"""

from __future__ import print_function

import os, sys

if __name__ == "__main__":

    debug = 0

    if debug: stderr = os.fdopen(2, "w")

    if debug: print("this is stderr", file=stderr)

    abcd = os.read(0, 4)
    if debug: print("read(0):", abcd, file=stderr)
    if abcd != b"abcd":
        sys.exit(1)

    if debug: print("os.write(1, righto)", file=stderr)
    os.write(1, b"righto")

    efgh = os.read(3, 4)
    if debug: print("read(3):", file=stderr)
    if efgh != b"efgh":
        sys.exit(2)

    if debug: print("os.close(4)", file=stderr)
    os.close(4)

    eof = os.read(5, 4)
    if debug: print("read(5):", eof, file=stderr)
    if eof != b"":
        sys.exit(3)

    if debug: print("os.write(1, closed)", file=stderr)
    os.write(1, b"closed")

    if debug: print("sys.exit(0)", file=stderr)
    sys.exit(0)