natsio-testing

Run real nats-server processes from your test suite: start/stop, temporary config files, free-port allocation, readiness probing (plaintext and TLS-handshake-first), and fault injection (kill()).

from natsio.testing import NatsServerProcess

async def test_against_a_real_server():
    server = await NatsServerProcess(binary="nats-server").start()
    try:
        nc = await natsio.connect(server.url)
        ...
    finally:
        await server.stop()

Binary discovery: pass binary= explicitly, or use find_server_binary() (checks NATS_SERVER_BIN, then nats-server on PATH).

Part of the natsio extension tier: distribution natsio-testing, imported as natsio.testing. Pre-1.0, no API-stability promises.