cypress-hmr-restarter

A rudimentary Cypress plugin(?) for automatically restarting tests after Webpack Hot Module Replacement (HMR) updates.


Setup

$3

``shell
npm install --save-dev cypress-hmr-restarter
`

$3

`js
// E.g. in cypress/support/index.js

// For webpack HMR (used in e.g. create-react-app or angular 11+)
import 'cypress-hmr-restarter';

// For webpack-hot-middleware (used in e.g. gatsby)
import 'cypress-hmr-restarter/gatsby';
`

$3

`jsonc
// E.g. in cypress.json
{
// Works with e.g. default create-react-app configuration
"baseUrl": "http://localhost:3000"
}
`

Options

`jsonc
{
// Overriding then URL used to connect, otherwise created from the baseUrl
"hmrUrl": "ws://localhost:3000/sockjs-node", // Default import
"hmrUrl": "ws://localhost:3000/websocket", // Angular 11+ import
"hmrUrl": "http://localhost:3000/__webpack_hmr", // Gatsby import

// Overrides delay between event and restart (ms)
"hmrRestartDelay": 1500
}
`

What it does

When using the Cypress Test Runner (cypress open), after the window has loaded, it will try to connect and listen for events. When an event signifying a change has happened, it will first try clicking the stop button, and then, after a short delay, it will click the restart button.

- The default import connects to the webpack-dev-server websocket at either or ws:///sockjs-node (wss: if https:), and listens for messages with the type invalid.

IMPORTANT: You need to ensure that transportMode option of webpack-dev-server is set to ws for the feature to work.

- The gatsby import connects to the webpack-hot-middleware event source at either or /__webpack_hmr, and listens for messages with the action built`.