Is it possible to use Jest with multiple presets at the same time?

Question

Is it possible to use Jest with multiple presets, say jsdom and react-native?

I'd like to test a React component that can work both on Web and in a React Native environment. The problem is that the component may use either React Native libraries or some document's methods.

When I run some tests, jest replies:

Cannot find module 'NetInfo' from 'react-native-implementation.js'

When I try to add

"jest": {   "preset": "react-native" } 

to package.json, I get:

ReferenceError: window is not defined

Answer 1

Presets are just plain Javascript objects, so in many circumstances you may simply merge them. For example, that's how I'm enabling ts-jest and jest-puppeteer simultaneously:

const merge = require('merge') const ts_preset = require('ts-jest/jest-preset') const puppeteer_preset = require('jest-puppeteer/jest-preset')  module.exports = merge.recursive(ts_preset, puppeteer_preset, {     globals: {         test_url: `http://${process.env.HOST || '127.0.0.1'}:${process.env.PORT || 3000}`,     }, }) 

If there are certain options that can't be 'merged' like that, just handle these cases manually.

Answer 2

Along these same lines, you can do this with the spread operator:

 const tsPreset = require('ts-jest/jest-preset') const puppeteerPreset = require('jest-puppeteer/jest-preset')  module.exports = {   ...tsPreset,   ...puppeteerPreset,   globals: {     test_url: `http://${process.env.HOST||'127.0.0.1'}:${process.env.PORT||3000}`,   },  }