Zero-Config Test Runner: JWT Auto-Gen and No Setup Docs

#testing #ai #devops #javascript

Here's a thing I've built more than once: a test automation runner that works perfectly on my machine and is a complete mystery to everyone else.

The usual failure mode:

Private key has to live in a specific path
Three env vars need to be exported
You need to know which bundle and cloud flag to pass
There's a doc somewhere explaining this, probably out of date

I just fixed all of that. Here's the new interface:

./run-test.sh smoke-tests

That's it. Optional args for tag, bundle, and cloud target if you need them. Otherwise: just works.

How it works

JWT generated at runtime. The script finds jwt-private-key.pem in the repo root (RS256, no expiry needed for test runs). No env var. No "where do I put this file" question.

JWT=$(node tools/generate-jwt.js)

Firebase key resolved automatically. Checks the repo root first, falls back to ~/.ssh/. Works the same on a fresh clone as it does on my laptop.

const keyPath = fs.existsSync('./firebase-key.json')
  ? './firebase-key.json'
  : path.join(os.homedir(), '.ssh', 'firebase-key.json');

One optional arg. Need to target a specific bundle or cloud env? Pass it. Otherwise the defaults are sane.

The Claude catch

Built this pairing with Claude Opus. It caught something I'd missed: my JWT generation had an expiry set that would silently break test runs longer than the token lifetime. Not a crash — just stale auth, failing tests, no obvious error.

That's the kind of thing that only shows up at 2am. Fixed it before it shipped.