tests/seq.py

tests: add a module that can perform the equivalent of `SIGKILL` on any OS

I started with this being Windows specific, but let's push all of the decision
making into this function so that it can just be called by the tests.  The
tradeoff is that this is very specific to sending `SIGKILL`- since
`signal.SIGKILL` doesn't exist on Windows, the desired signal can't be passed
from the caller.  Maybe there's a way, but let's wait until there's a need.

We don't use `killdaemons.py` unconditionally because it starts with a more
graceful `SIGTERM` on posix.

#!/usr/bin/env python3
#
# A portable replacement for 'seq'
#
# Usage:
#   seq STOP              [1, STOP] stepping by 1
#   seq START STOP        [START, STOP] stepping by 1
#   seq START STEP STOP   [START, STOP] stepping by STEP

import io
import sys

sys.stdout = io.TextIOWrapper(
    sys.stdout.buffer,
    sys.stdout.encoding,
    sys.stdout.errors,
    newline="\n",
)

start = 1
if len(sys.argv) > 2:
    start = int(sys.argv[1])

step = 1
if len(sys.argv) > 3:
    step = int(sys.argv[2])

stop = int(sys.argv[-1]) + 1

for i in range(start, stop, step):
    print(i)