jest-runner-prettier

1.0.0 verified Sat Apr 25 auth: no javascript

A Jest runner that formats files using Prettier. Current stable version is 1.0.0, released February 2022. It integrates Prettier into Jest as a custom runner, allowing you to check formatting as part of your test suite. Requires Jest >= 27.0.0 and Prettier >= 1.8. Ships TypeScript definitions. Key differentiator: provides a built-in Jest preset for easy configuration, supports all file types Prettier handles, and produces diff output on formatting failures. Suitable for CI pipelines to enforce consistent code style.

Common errors

error Cannot find module 'jest-runner-prettier' ↓

cause The package is not installed or not in node_modules.

fix

Run npm install --save-dev jest prettier jest-runner-prettier

error Cannot use import statement outside a module ↓

cause The package is ESM-only from v1.0.0, but project is configured as CommonJS.

fix

Set type: 'module' in package.json or use a CommonJS-compatible version (<1.0.0).

error Configuration error: Unknown runner "prettier" ↓

cause Jest cannot find the runner because the package is not installed or configured incorrectly.

fix

Ensure jest-runner-prettier is installed and listed in devDependencies.

Warnings

breaking v1.0.0 requires Jest >= 27 and Node >= 12. Also targets ES modules, breaking CJS usage. ↓

fix Upgrade Jest to at least 27, Node to >=12, and ensure your project supports ESM or use a bundler.

deprecated Version 0.3.x uses jest-diff v24, which may cause compatibility issues with Jest 27. ↓

fix Upgrade to v1.0.0 or later.

gotcha The package name in Jest runner config is 'prettier' not 'jest-runner-prettier'. ↓

fix Use runner: 'prettier' in Jest config.

Install

npm install jest-runner-prettier

yarn add jest-runner-prettier

pnpm add jest-runner-prettier

Imports

jest-runner-prettier
wrong
```
const runner = require('jest-runner-prettier')
```
correct
```
import 'jest-runner-prettier'
```
The package does not export a symbol; it's a Jest runner used via configuration. v1.0.0 is ESM-only, so require() fails on Node 12+ with ESM.
preset
wrong
```
module.exports = { preset: 'jest-runner-prettier/preset' }
```
correct
```
module.exports = { preset: 'jest-runner-prettier' }
```
The preset is accessed via the package name itself, not a subpath. The README shows 'preset: "jest-runner-prettier"'.
runner
wrong
```
module.exports = { runner: 'jest-runner-prettier' }
```
correct
```
module.exports = { runner: 'prettier' }
```
The runner name in Jest config is 'prettier' (derived from the package), not the full package name.

Quickstart

Installs dependencies, configures Jest with the preset, and runs the formatter as a test.

npm install --save-dev jest prettier jest-runner-prettier

# jest.config.js
module.exports = {
  preset: 'jest-runner-prettier',
};

# or manually:
// module.exports = {
//   runner: 'prettier',
//   moduleFileExtensions: ['js', 'ts', 'json', 'md'],
//   testMatch: ['**/*.js', '**/*.ts', '**/*.json', '**/*.md'],
// };

# Run Jest
npx jest