Cypress Rollup Preprocessor

1.2.0 verified Fri May 01 auth: no javascript

A Cypress preprocessor that bundles JavaScript test files using Rollup. Version 1.2.0, released 2022-06-18, is the latest stable release. The package is maintained with semantic versioning; breaking changes are documented in changelogs. It supports Cypress >=10 (ESM config) and <=9 (CJS config). Unlike alternatives like cy-rollup, this package closely follows the official Cypress preprocessor API and supports full Rollup input/output options, TypeScript configs, and watch mode. It requires Rollup 2.x as a peer dependency and ships TypeScript type definitions.

Common errors

error Cannot find module 'cypress-rollup-preprocessor' ↓

cause Package not installed or missing peer dependencies.

fix

Run npm install cypress-rollup-preprocessor rollup@^2.0.0 --save-dev

error Error: rollupOptions is not a function ↓

cause Option name changed in v0.7.0 from 'rollupOptions' to 'inputOptions'/'outputOptions'.

fix

Use rollupPreprocessor({ inputOptions, outputOptions }) instead of rollupPreprocessor({ rollupOptions })

error TypeError: rollupPreprocessor is not a function ↓

cause Incorrect import or destructuring; default export not used correctly.

fix

Use import rollupPreprocessor from 'cypress-rollup-preprocessor' (ESM) or const rollupPreprocessor = require('cypress-rollup-preprocessor') (CJS).

Warnings

breaking In v0.7.0, the option 'rollupOptions' was renamed to 'inputOptions' and 'outputOptions'. Using 'rollupOptions' will cause a runtime error. ↓

fix Replace `rollupOptions` with `inputOptions` and `outputOptions` separately. Example: rollupPreprocessor({ inputOptions, outputOptions })

deprecated Cypress <=9 support is deprecated; newer versions may drop CJS require pattern. ↓

fix Migrate to Cypress >=10 and use ESM syntax: import rollupPreprocessor from 'cypress-rollup-preprocessor'

gotcha If you use TypeScript without 'esModuleInterop', default import may fail. Users incorrectly destructure the export. ↓

fix Use `import rollupPreprocessor from 'cypress-rollup-preprocessor'` with esModuleInterop, or use `const rollupPreprocessor = require('cypress-rollup-preprocessor')` in CJS.

gotcha The preprocessor only supports Rollup 2.x. Using Rollup 3.x or 4.x will cause incompatibility errors. ↓

fix Install rollup@2.x as a peer dependency: npm install rollup@^2.0.0 --save-dev

Install

npm install cypress-rollup-preprocessor

yarn add cypress-rollup-preprocessor

pnpm add cypress-rollup-preprocessor

Imports

default (rollupPreprocessor)
wrong
```
const rollupPreprocessor = require('cypress-rollup-preprocessor').default
```
correct
```
import rollupPreprocessor from 'cypress-rollup-preprocessor'
```
Default export; CJS users must use require('cypress-rollup-preprocessor') without .default, but TypeScript users may need .default if esModuleInterop is off.

default (CJS require)

wrong

const { rollupPreprocessor } = require('cypress-rollup-preprocessor')

correct

const rollupPreprocessor = require('cypress-rollup-preprocessor')

The package exports a single function as default. Destructuring will fail.

TypeScript type imports

wrong

import { CypressRollupPreprocessorOptions } from 'cypress-rollup-preprocessor'

correct

import type { CypressRollupPreprocessorOptions } from 'cypress-rollup-preprocessor'

Types are exported as named exports. Use `import type` for tree-shaking in TypeScript.

Quickstart

Shows how to use the preprocessor with Cypress >=10, including default usage and custom Rollup options.

// cypress.config.ts (Cypress >=10)
import { defineConfig } from 'cypress'
import rollupPreprocessor from 'cypress-rollup-preprocessor'

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

// For custom Rollup options:
import rollupConfig from './rollup.config'
const { output: outputOptions, ...inputOptions } = rollupConfig
on('file:preprocessor', rollupPreprocessor({ inputOptions, outputOptions }))