jest-dev-server

Starts a server before your Jest tests and tears it down after.

Why

jest-puppeteer works great for running tests in Jest using Puppeteer.
It's also useful for starting a local development server during the tests without letting Jest hang.
This package extracts just the local development server spawning without any ties to Puppeteer.

Install

 npm install --save-dev jest-dev-server

Usage

jest-dev-server exports setup and teardown functions.

 // global-setup.js
const { setup: setupDevServer } = require("jest-dev-server");

module.exports = async function globalSetup() {
  globalThis.servers = await setupDevServer({
    command: `node config/start.js --port=3000`,
    launchTimeout: 50000,
    port: 3000,
  });
  // Your global setup
};

 // global-teardown.js
const { teardown: teardownDevServer } = require("jest-dev-server");

module.exports = async function globalTeardown() {
  await teardownDevServer(globalThis.servers);
  // Your global teardown
};

Specify several servers

You can specify several servers using an array of configs:

 // global-setup.js
const { setup: setupDevServer } = require("jest-dev-server");

module.exports = async function globalSetup() {
  globalThis.servers = await setupDevServer([
    {
      command: "node server.js",
      port: 4444,
    },
    {
      command: "node server2.js",
      port: 4445,
    },
  ]);
  // Your global setup
};

Options

command

Type: string, required.

Command to execute to start the port.
Directly passed to spawnd.

 const options = {
  command: "npm run start",
};

debug

Type: boolean, default to false.

Log server output, useful if server is crashing at start.

 const options = {
  command: "npm run start",
  debug: true,
};

launchTimeout

Type: number, default to 5000.

How many milliseconds to wait for the spawned server to be available before giving up.
Defaults to wait-port's default.

 const options = {
  command: "npm run start",
  launchTimeout: 30000,
};

Following options are linked to spawnd.

host

Type: string, if not specified it will used Node.js default port.

Host to wait for activity on before considering the server running.
Must be used in conjunction with port.

 const options = {
  command: "npm run start --port 3000",
  host: "customhost.com",
  port: 3000,
};

path

Type: string, default to null.

Path to resource to wait for activity on before considering the server running.
Must be used in conjunction with host and port.

 const options = {
  command: "npm run start --port 3000",
  host: "customhost.com",
  port: 3000,
  path: "thing",
};

protocol

Type: string, (https, http, tcp, socket) default to tcp.

To wait for an HTTP or TCP endpoint before considering the server running, include http or tcp as a protocol.
Must be used in conjunction with port.

 const options = {
  command: "npm run start --port 3000",
  protocol: "http",
  port: 3000,
};

port

Type: number, default to null.

Port to wait for activity on before considering the server running.
If not provided, the server is assumed to immediately be running.

 const options = {
  command: "npm run start --port 3000",
  port: 3000,
};

usedPortAction

Type: string (ask, error, ignore, kill) default to ask.

It defines the action to take if port is already used:

• ask: a prompt is shown to decide if you want to kill the process or not
• error: an errow is thrown
• ignore: your test are executed, we assume that the server is already started
• kill: the process is automatically killed without a prompt

 const options = {
  command: "npm run start --port 3000",
  port: 3000,
  usedPortAction: "kill",
};

waitOnScheme

jest-dev-server use the wait-on npm package to wait for resources to become available before calling callback.

Type: object, default to {}.

• delay: optional initial delay in ms, default 0
• interval: optional poll resource interval in ms, default 250ms
• log: optional flag which outputs to stdout, remaining resources waited on and when complete or errored
• reverse: optional flag to reverse operation so checks are for resources being NOT available, default false
• timeout: optional timeout in ms, default Infinity. Aborts with error
• tcpTimeout: optional tcp timeout in ms, default 300ms
• verbose: optional flag which outputs debug output, default false
• window: optional stabilization time in ms, default 750ms. Waits this amount of time for file sizes to stabilize or other resource availability to remain unchanged

Note: http(s) specific options, see https://github.com/request/request#readme for specific details

 const options = {
  command: "npm run start --port 3000",
  port: 3000,
  usedPortAction: "kill",
  waitOnScheme: {
    delay: 1000,
  },
};

Troubleshooting

• If using port makes the terminal to ask for root password although the port is valid and accessible then use usePortAction: 'ignore'.