Presets

Set a preset with Jest’s preset key:

jest.config.mjs

export default {
  preset: '@repobuddy/jest/presets/ts-esm',
}

Each preset is exported as @repobuddy/jest/presets/<name> and as @repobuddy/jest/presets/<name>/jest-preset, in ESM and CommonJS builds. The same objects are on the presets namespace of the main entry.

Preset	Language	Module format	Environment	Transform
ts	TypeScript	from package.json type	node	as ts-esm or ts-cjs
ts-esm	TypeScript	ESM	node	@swc/jest
ts-cjs	TypeScript	CommonJS	node	ts-jest, jest-esm-transformer-2
js-esm	JavaScript	ESM	node	Jest’s default
js-cjs	JavaScript	CommonJS	node	jest-esm-transformer-2
jsdom-ts	TypeScript	from package.json type	jsdom	as jsdom-ts-esm or jsdom-ts-cjs
jsdom-ts-esm	TypeScript	ESM	jsdom	@swc/jest
jsdom-ts-cjs	TypeScript	CommonJS	jsdom	ts-jest, jest-esm-transformer-2
watch	any	any	any	none, watch plugins only

-watch variants

Each preset above except watch has a -watch variant. The variant is the base preset plus the watchPlugins of the watch preset, and nothing else.

Base	Variant
ts	ts-watch
ts-esm	ts-esm-watch
ts-cjs	ts-cjs-watch
js-esm	js-esm-watch
js-cjs	js-cjs-watch
jsdom-ts	jsdom-ts-watch
jsdom-ts-esm	jsdom-ts-esm-watch
jsdom-ts-cjs	jsdom-ts-cjs-watch

What every preset except watch sets

• roots and collectCoverageFrom for one source folder. See configs.configSource().
• testEnvironment and the test file patterns. See test file names.
• The transform settings for its language and module format.

How your config combines with a preset

Jest applies these rules (from jest-config 30):

• Keys in your config replace the preset’s keys.
• moduleNameMapper and transform merge. Your patterns come first, then the preset’s patterns that you did not repeat. Jest uses the first transform pattern that matches a file.
• setupFiles and setupFilesAfterEnv concatenate: the preset’s entries, then yours.

See customize a preset.