py.test + ngrok (localtunnel)

conftest.py

import contextlib
import distutils.spawn
import functools
import re
import signal
import subprocess

from pytest import fixture, skip


def pytest_addoption(parser):
    parser.addoption(
        '--ngrok',
        default=distutils.spawn.find_executable('ngrok'),
        help='path to ngrok [%default]'
    )


NGROK_LOG_PATTERN = re.compile(
    rb'\[client\]\s+Tunnel\s+established\s+at\s+(https?://\S+)',
    re.IGNORECASE
)


@contextlib.contextmanager
def ngrok_context(ngrok_path, port):
    p = subprocess.Popen(
        [ngrok_path, '-proto=https', '-log=stdout', str(port)],
        stderr=subprocess.DEVNULL,
        stdout=subprocess.PIPE
    )
    # Detecting public address by grepping log
    while True:
        for line in p.stdout:
            m = NGROK_LOG_PATTERN.search(line)
            if m:
                public_addr = m.group(1).decode()
                print('ngrok_context:', public_addr)
                yield public_addr
                return
        else:
            try:
                p.wait(0.5)
            except subprocess.TimeoutExpired:
                continue
            else:
                return


@fixture
def fx_ngrok_context(request):
    ngrok_path = request.config.getoption('--ngrok')
    if not ngrok_path:
        skip('--ngrok is missing; skipped...')
    return functools.partial(ngrok_context, ngrok_path)