rollup-jest

3.1.0 verified Mon Apr 27 auth: no javascript

Rollup preprocessor for Jest that transforms files using Rollup. Current version 3.1.0, actively maintained. Allows using Rollup plugins and configuration in Jest tests, supporting ES modules. Key differentiator: integrates Rollup's bundling and plugin ecosystem into Jest's transform pipeline, enabling features like plugin injection, caching, and custom resolve behavior. Peer dependency on Rollup ^2.3.0 || ^3. Provides preset for zero-config setup. Suitable for projects already using Rollup who want to reuse rollup config in tests.

Common errors

error Cannot find module 'rollup-jest' ↓

cause rollup-jest not installed or not in devDependencies

fix

npm install rollup-jest rollup --save-dev

error Cannot use import statement outside a module ↓

cause Jest not configured to transform the file with rollup-jest

fix

Add rollup-jest to Jest transform in jest.config.json

error Jest encountered an unexpected token - SyntaxError: Unexpected token 'export' ↓

cause File not transformed because transform pattern doesn't match

fix

Ensure the file extension matches the regex in Jest config (e.g., "\\.m?js$")

Warnings

breaking Version 3 requires Rollup ^2.3.0 or ^3. Version 2 required Rollup ^1.0.0. ↓

fix Upgrade Rollup to ^2.3.0 or ^3 if using rollup-jest v3.

deprecated The 'useCache' option may cause issues with plugins that have state (e.g. TypeScript). ↓

fix Set 'useCache: false' if experiencing stale results.

gotcha To use ESM configFile with Rollup v3, you must add --experimental-vm-modules to Node.js flags. ↓

fix Run Jest with NODE_OPTIONS=--experimental-vm-modules npm run test

gotcha Default transform only matches .mjs and .js files. Other extensions like .ts or .jsx are not transformed unless explicitly added. ↓

fix Add a custom transform pattern for other extensions, e.g. "\\.ts$": "rollup-jest"

Install

npm install rollup-jest

yarn add rollup-jest

pnpm add rollup-jest

Imports

default (preset)

wrong

Using require('rollup-jest') in jest config

correct

// In jest.config.json: "preset": "rollup-jest"

Used as a Jest preset, not imported directly.

transform entry

wrong

Trying to import rollup-jest as a module in test files

correct

// In jest.config.json: "transform": { "\\.m?js$": "rollup-jest" }

Configured in Jest's transform field, not imported in user code.

with options

wrong

Passing options as second argument to import statement

correct

// In jest.config.json: "transform": { "\\.js$": ["rollup-jest", {"configFile": "./rollup.config.js"}] }

Options are passed as array in Jest transform config.

Quickstart

Install, configure preset, and write ES module test with default import.

npm install rollup-jest rollup --save-dev
# jest.config.json
{
  "jest": {
    "preset": "rollup-jest"
  }
}
# __tests__/example.test.js
import path from 'path';
test('parses extname', () => {
  expect(path.extname('foo.md')).toBe('.md');
});