How to wait for server start complete from an npm script?

Question

I'm trying to run a functional test for a node app.

In my package.json I have the following scripts:

"scripts": {
  "web-server": "NODE_ENV=test node app.js &",
  "test": "npm run web-server && mocha ./tests/functional/*.js --exit",
  "posttest": "pkill -f node"
}

But when running it, tests run before the server completes starting.

How can I wait for the server?

Answer 1

I found wait-on today and like its approach. It only does the wait, not other things like command launching.

Using it with concurrently, like so:

"scripts": {
    "xxx": "concurrently -n server,mocha \"npm run web-server\" \"npx wait-on http://localhost:8080 && npx mocha ...\"",

Wanted to mention to new visitors. I think wait-on is currently the best fitting answer to the title's question.