jest-dev-server

What is jest-dev-server?

The jest-dev-server package is a utility for running a development server while running Jest tests. It is particularly useful for end-to-end (E2E) testing where you need a server to be up and running before executing your tests.

What are jest-dev-server's main functionalities?

Starting a development server

This feature allows you to start a development server before running your tests. The `setupDevServer` function takes an object with a `command` to start the server and a `port` to listen on.

const { setup: setupDevServer } = require('jest-dev-server');

beforeAll(async () => {
  await setupDevServer({
    command: 'npm run start',
    port: 3000,
  });
});

Stopping the development server

This feature allows you to stop the development server after your tests have completed. The `teardownDevServer` function ensures that the server is properly shut down.

const { teardown: teardownDevServer } = require('jest-dev-server');

afterAll(async () => {
  await teardownDevServer();
});

Custom server options

This feature allows you to customize the server options such as `launchTimeout` and `debug` mode. This is useful for fine-tuning the server startup process to match your specific needs.

const { setup: setupDevServer } = require('jest-dev-server');

beforeAll(async () => {
  await setupDevServer({
    command: 'npm run start',
    port: 3000,
    launchTimeout: 50000,
    debug: true,
  });
});

Other packages similar to jest-dev-server

start-server-and-test

The start-server-and-test package is another utility for starting a server and running tests. It is more versatile as it can be used with any test runner, not just Jest. It also provides more flexibility in terms of waiting for the server to be ready before running tests.

wait-on

The wait-on package is a utility that waits for files, ports, sockets, and http(s) resources to become available. It can be used in conjunction with other tools to ensure that a server is up and running before executing tests. It is more general-purpose compared to jest-dev-server.

concurrently

The concurrently package allows you to run multiple commands concurrently. It can be used to start a server and run tests in parallel. While it does not provide the same level of integration with Jest as jest-dev-server, it is a powerful tool for managing multiple processes.

README

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.

Usage

jest-dev-server exports setup and teardown functions.

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

module.exports = async function globalSetup() {
  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()
  // Your global teardown
}

Options

command

Type: string, required.

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

module.exports = {
  command: 'npm run start',
}

debug

Type: boolean, default to false.

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

module.exports = {
  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.

module.exports = {
  command: 'npm run start',
  launchTimeout: 30000,
}

options

Type: object, default to {}.

Any other options to pass to spawnd.

host

Type: string, default to localhost.

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

module.exports = {
  command: 'npm run start --port 3000',
  host: 'customhost.com',
  port: 3000,
}

protocol

Type: string, default to null.

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

module.exports = {
  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.

module.exports = {
  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

module.exports = {
  command: 'npm run start --port 3000',
  port: 3000,
  usedPortAction: 'kill',
}

License

MIT

Changelog

3.4.0 (2018-09-24)

Bug Fixes

• support several instances of Jest in parallel (#138) (275bc71)

Features

• expect-puppeteer: Update default options to look at connect object (1f33ea0)
• jest-environment-puppeteer: Add ability to connect to an already existing instance of Chrome (9de05f0)
• jest-environment-puppeteer: Add documentation of new connect options (c6b0613)
• jest-environment-puppeteer: Remove unneeded async config (30a3daa)
• jest-environment-puppeteer: Simplify getBrowser function (8ccb0d0)

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