Supercharge your Cypress E2E tests using Vite

If you’ve been a front-end developer for a while now, you’ve probably used cypress and Vite, or at least heard about them (if you haven’t, you need to check them out). Using these together makes developing and testing web applications a breeze. But still, there is something missing: Cypress doesn’t use Vite for running end-to-end tests.

Cypress 10 introduced Vite integration, but only for component testing. To run end-to-end tests, however, you still need Webpack, and it’s a hell of a nightmare. You need to configure everything twice: once in Vite and once in Webpack. For example, imagine that you are using typescript with path aliases in your project. You need to configure aliases for typescript and Vite (luckily, you can use a Vite plugin instead of doing manual configuration), and now your tests stop working. You should either not use aliases in your tests or do the same configurations for Webpack separately. And by the way, you need to configure Webpack to load typescript as well.

It’s not finished yet. Every time you change a configuration in your development environment that affects your tests, you need to do the same thing to update the Webpack configurations. You may also use some tools or plugins in your dev environment that are incompatible with Webpack, or vice versa.

Besides the development experience, the gap between development and testing environments can lead to unexpected bugs and make the tests unreliable.

Besides the fact that Vite is faster than Webpack, using Vite for end-to-end testing can eliminate the gap between these two environments and make it much easier to change the project structure and configurations. You can also use Vite-specific features like import.meta and Vite or Rollup plugins to empower your testing workflow. Accessing environment variables or application-specific configurations in tests is possible too.

But how can we use Vite for running end-to-end tests? To do so, we need a Cypress preprocessor. But don’t worry, I’m not going to walk you through the preprocessor API and how to write one; cause that’s already done, and cypress-vite does the job for you.

First, you need to install cypress-vite in your project:

npm install --save-dev cypress-vite

yarn add --dev cypress-vite

pnpm add --save-dev cypress-vite

Then update your cypress configuration file:

import { defineConfig } from 'cypress'
import vitePreprocessor from 'cypress-vite'

export default defineConfig({
  e2e: {
    setupNodeEvents(on) {
      on('file:preprocessor', vitePreprocessor())
    },
  },
})

That’s it. Now cypress uses Vite for running your end-to-end tests. It will automatically resolve your Vite configuration or you can pass in the path to your configuration file. You can check its repository for more examples and documentation.