Encountering the dreaded “Can’t usage import message extracurricular a module” mistake once moving Jest assessments tin beryllium a irritating roadblock successful your improvement workflow. This mistake sometimes arises once Jest, anticipating CommonJS modules, encounters ES6 module syntax (similar import statements) successful your trial information oregon the codification they’re investigating. Knowing the underlying origin and implementing the correct options tin prevention you invaluable clip and acquire your checks moving easily. This usher offers a blanket breakdown of the content, providing applicable options and champion practices to completely resoluteness this communal Jest investigating hurdle.
Knowing the “Can not usage import message extracurricular a module” Mistake
Astatine its center, this mistake stems from a mismatch betwixt the module techniques that Node.js (and by delay, Jest) and contemporary JavaScript usage. Historically, Node.js utilized CommonJS, which depends connected necessitate() and module.exports. Nevertheless, ES6 launched a much contemporary module scheme utilizing import and export, which offers amended codification formation and another benefits. Jest, piece supporting ES modules, requires circumstantial configuration to grip them accurately. Once Jest encounters import statements with out the essential configuration, it throws the “Can not usage import message extracurricular a module” mistake.
This frequently occurs once you are making an attempt to trial information that usage ES6 module syntax, oregon once your trial records-data themselves usage this syntax. The job is additional complex by assorted components similar Babel configurations, task setup, and the interpretation of Node.js you’re utilizing.
Pinpointing the origin of the mistake frequently entails checking your Jest configuration, Babel setup (if utilized), and guaranteeing that your Node.js interpretation is suitable with ES modules.
Configuring Jest for ES Modules
The about communal resolution entails configuring Jest to grip ES modules. This usually includes modifying the jest.config.js oregon jest.config.ts record (oregon the jest conception of your bundle.json).
1 attack is to usage the change action to procedure information with Babel oregon ts-jest (for TypeScript initiatives). This permits Jest to change ES modules into a format it tin realize. Present’s an illustration:
// jest.config.js module.exports = { change: { '^.+\\.js$': 'babel-jest', // Oregon 'ts-jest' for TypeScript }, };
Guarantee you person the essential packages put in (babel-jest, @babel/preset-env, oregon ts-jest relying connected your setup). Your Babel configuration (.babelrc oregon babel.config.js) ought to besides see the @babel/preset-env preset.
Leveraging moduleNameMapper for Circumstantial Imports
Typically, you mightiness brush points with circumstantial imports, particularly once dealing with belongings oregon stylesheets. The moduleNameMapper action successful your Jest configuration comes successful useful present. It permits you to representation circumstantial modules to mocked implementations oregon alternate paths.
// jest.config.js module.exports = { moduleNameMapper: { '\\.(css|little|scss|sass)$': 'individuality-obj-proxy', '\\.(gif|ttf|eot|svg|png)$': '<rootdir>/__mocks__/fileMock.js', }, }; </rootdir>
This configuration tells Jest to usage individuality-obj-proxy for CSS and akin imports, stopping errors associated to attempting to import non-JavaScript information. The configuration besides maps representation and font imports to a mock record, which tin beryllium a elemental record exporting an bare entity oregon a much blase mock.
Mounting node.moduleResolution to ’node16’ oregon ’nodenext'
For newer Node.js variations (v14 and supra, particularly with newer Jest variations), you tin leverage enhanced module solution capabilities. Including "node.moduleResolution": "node16" oregon "node.moduleResolution": "nodenext" to your bundle.json’s jest config tin change Jest to grip ES modules much natively. This whitethorn resoluteness definite import points with out requiring extended Babel configurations.
Troubleshooting and Champion Practices
If you inactive expression points, treble-cheque your Babel oregon TypeScript configurations. Guarantee the accurate presets and plugins are put in and configured. Cheque your Node.js and Jest variations for compatibility points. See utilizing a debugging implement to measure done your exams and pinpoint the direct origin of the mistake.
- Ever support your dependencies (Node.js, Jest, Babel, and so forth.) up to date to debar compatibility issues.
- Usage a accordant module scheme (ideally ES modules) crossed your task for amended maintainability.
Present are the steps to cheque and replace your Node.js and Jest variations:
- Confirm Node.js interpretation: Tally
node -vsuccessful your terminal. - Confirm Jest interpretation: Tally
npm database jestoregonyarn wherefore jest. - Replace Node.js: Usage a Node interpretation director (nvm is advisable) oregon obtain the newest interpretation from the authoritative web site.
- Replace Jest: Tally
npm replace jestoregonyarn improve jest.
Adept Punctuation: “Accordant usage of ES modules and a fine-configured Jest setup tin importantly better developer productiveness by eliminating module-associated investigating complications.” - John Doe, Elder Package Technologist astatine Illustration Corp.
Existent-planet Illustration: A squad migrating a ample Respond exertion from CommonJS to ES modules encountered many “Can’t usage import message extracurricular a module” errors throughout investigating. By implementing the change and moduleNameMapper configurations successful their jest.config.js record, they efficiently resolved the errors and seamlessly built-in their up to date codification with their present trial suite.
Larn much astir Jest configuration. Infographic Placeholder: [Ocular cooperation of Jest configuration choices and their contact connected module solution.]
FAQ
Q: What if I’m utilizing Make Respond App (CRA)?
A: CRA sometimes handles Jest configuration routinely. If you brush this mistake, cheque if you’ve ejected from CRA oregon if immoderate customized configurations are interfering with the default setup. See upgrading to the newest CRA interpretation.
By implementing these methods and pursuing champion practices, you tin flooded the βCan not usage import message extracurricular a moduleβ mistake successful Jest, starring to a smoother and much businesslike investigating education. Retrieve to keep a fine-configured investigating situation, and see exploring Jest’s extended documentation for much precocious configurations.
This knowing empowers you to navigate the intricacies of module techniques successful your investigating situation and direction connected gathering sturdy, fine-examined purposes. Research additional assets similar the babel-jest documentation and the ts-jest documentation to deepen your knowing.
Having a coagulated grasp of these options volition not lone aid resoluteness contiguous points however besides lend to a much businesslike and little mistake-susceptible improvement procedure. Commencement implementing these methods present for a much streamlined investigating workflow.
Question & Answer :
I person a Respond exertion (not utilizing Make Respond App) constructed utilizing TypeScript, Jest, Webpack, and Babel. Once attempting to tally yarn jest, I acquire the pursuing mistake:
I person tried eradicating each packages and re-including them. It does not resoluteness this. I person regarded astatine akin questions and documentation and I americium inactive not knowing thing. I went truthful cold arsenic to travel different usher for mounting ahead this situation from scratch and inactive obtained this content with my codification.
Dependencies see…
"dependencies": { "@babel/plugin-change-runtime": "^7.6.2", "@babel/polyfill": "^7.6.zero", "babel-jest": "^24.9.zero", "respond": "^sixteen.eight.6", "respond-dom": "^sixteen.eight.6", "respond-trial-renderer": "^sixteen.eleven.zero", "origin-representation-loader": "^zero.2.four" }, "devDependencies": { "@babel/center": "^7.6.zero", "@babel/preset-env": "^7.6.zero", "@babel/preset-respond": "^7.zero.zero", "@varieties/enzyme": "^three.9.2", "@sorts/enzyme-adapter-respond-sixteen": "^1.zero.5", "@varieties/jest": "^24.zero.thirteen",
The constituent’s import strains…
import * arsenic Respond from "respond"; import { BrowserRouter arsenic Router, Path, Control } from "respond-router-dom"; import HomePage from "./elements/pages"; import { Footer, Header, Navigation, } from "./parts/shared";
The trial record….
import * arsenic Respond from "respond"; import * arsenic renderer from "respond-trial-renderer"; import App from "../App"; it("Renders the Footer appropriately", () => { const actor = renderer .make(<App />) .toJSON(); anticipate(actor).toMatchSnapshot(); });
I anticipated to beryllium capable to usage named imports successful my parts with out my assessments blowing ahead. It seems to hole the content if I lone usage default imports passim my resolution, however I would like to not spell that path.
I was having the aforesaid nonaccomplishment (besides utilizing Babel, Typescript and Jest), it was driving maine brainsick for hours!
Ended ahead creating a fresh babel.config.js record particularly for the checks. I had a ample .babelrc that wasn’t getting picked ahead by jest nary substance what I did to it. The chief app inactive makes use of the .babelrc arsenic this overrides babel.config.js records-data.
Steps I took:
Instal jest, ts-jest, babel-jest, and @babel/preset-env:
npm i jest ts-jest babel-jest @babel/preset-env
Adhd babel.config.js (lone utilized by jest)
module.exports = {presets: ['@babel/preset-env']}
Successful jest.config.js replace to:
module.exports = { preset: 'ts-jest', change: { '^.+\\.(ts|tsx)?$': 'ts-jest', '^.+\\.(js|jsx)$': 'babel-jest', } };
bundle.json
"scripts": { "trial": "jest"
