I have a React application (not using Create React App) built using TypeScript, Jest, Webpack, and Babel. When trying to run yarn jest, I get the following error:
I have tried removing all packages and re-adding them. It does not resolve this. I have looked at similar questions and documentation and I am still misunderstanding something. I went so far as to follow another guide for setting up this environment from scratch and still received this issue with my code.
Dependencies include...
"dependencies": {
"#babel/plugin-transform-runtime": "^7.6.2",
"#babel/polyfill": "^7.6.0",
"babel-jest": "^24.9.0",
"react": "^16.8.6",
"react-dom": "^16.8.6",
"react-test-renderer": "^16.11.0",
"source-map-loader": "^0.2.4"
},
"devDependencies": {
"#babel/core": "^7.6.0",
"#babel/preset-env": "^7.6.0",
"#babel/preset-react": "^7.0.0",
"#types/enzyme": "^3.9.2",
"#types/enzyme-adapter-react-16": "^1.0.5",
"#types/jest": "^24.0.13",
The component's import lines...
import * as React from "react";
import { BrowserRouter as Router, Route, Switch } from "react-router-dom";
import HomePage from "./components/pages";
import {
Footer,
Header,
Navigation,
} from "./components/shared";
The test file....
import * as React from "react";
import * as renderer from "react-test-renderer";
import App from "../App";
it("Renders the Footer correctly", () => {
const tree = renderer
.create(<App />)
.toJSON();
expect(tree).toMatchSnapshot();
});
I expected to be able to use named imports in my components without my tests blowing up. It appears to fix the issue if I only use default imports through my solution, but I would prefer to not go that route.
Also using Babel, Typescript and Jest. Had the same failure, driving me crazy for hours.
Ended up creating a new babel.config.js file specifically for the tests. Had a large .babelrc that wasn't getting picked up by jest no matter what i did to it. Main app still uses the .babelrc as this overrides babel.config.js files.
Install jest, ts-jest and babel-jest:
npm i jest ts-jest babel-jest
babel.config.js (only used by jest)
module.exports = {presets: ['#babel/preset-env']}
jest.config.js
module.exports = {
preset: 'ts-jest',
transform: {
'^.+\\.(ts|tsx)?$': 'ts-jest',
"^.+\\.(js|jsx)$": "babel-jest",
}
};
package.json
"scripts": {
"test": "jest"
Use Babel to transpile those JS Modules and you'll be able to write your tests with es6.
Install Babel/preset-env
npm i -D #babel/preset-env
Create a babel configuration file with the preset
//babel.config.js
module.exports = {presets: ['#babel/preset-env']}
I solved this by migrating the .babelrc file to babel.config.js! Shocker.
For future references,
I solved the problem by using below jest config, after reading Logan Shoemaker's answer.
module.exports = {
verbose: true,
setupFilesAfterEnv: ["<rootDir>src/setupTests.ts"],
moduleFileExtensions: ["js", "jsx", "ts", "tsx"],
moduleDirectories: ["node_modules", "src"],
moduleNameMapper: {
"\\.(css|less|scss)$": "identity-obj-proxy"
},
transform: {
'^.+\\.(ts|tsx)?$': 'ts-jest',
"^.+\\.(js|jsx)$": "babel-jest",
"\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/__mocks__/file.js",
}
};
try this thing if you are using babel 6
Adding #babel/plugin-transform-modules-commonjs in the plugin section of babel.config.js
or
For my case import issue was due to the react file drop by adding that to transformIgnorePatterns
"transformIgnorePatterns": ["/node_modules/(?!react-file-drop)"]
I fixed it by simply appending the pattern after the run statement in package.json runner
{
"scripts": {
...
"test": "react-scripts test --transformIgnorePatterns 'node_modules/(?!my-library-dir)/'"
...
Then, just run npm test
Solution: my named imports were coming from index.js files and I believe ts-jest needed them as index.ts files (I'm using Typescript). If anyone else runs into this error, couldn't hurt to check if you derped your file extensions.
I wasted a lot of time on this, unfortunately, but I learned a lot about webpack configurations and Babel.
Add your test script in package.json with Node experimental feature: --experimental-vm-modules
In this way you won't require babel or other dependencies.
Examples:
"test": "NODE_OPTIONS='--experimental-vm-modules --experimental-specifier-resolution=node' jest"
If you get this error: zsh: command not found: jest, try with node passing jest.js like this:
"test": "NODE_OPTIONS='--experimental-vm-modules --experimental-specifier-resolution=node --trace-warnings' node node_modules/jest/bin/jest.js --detectOpenHandles"
I'm surprised that none of the answers does not give an elegant solution:
jest.config.js
module.exports = {
...,
globals: {
"ts-jest": {
isolatedModules: true,
},
},
};
This compiles each file separately therefore avoiding the no exports issue.
Create .babelrc on the main directory and add this code and install these packages
#babel/core, #babel/preset-env and #babel/preset-react
{
"presets": [
[
"#babel/preset-env",
{
"modules": "commonjs"
}
],
"#babel/preset-react"
]
}
Matching file extensions:
I importing a file named Todo.jsx in the root as ./src/Todo/. Whenever I changed it to Todo.js the problem went away.
Disclaimer: I'm not sure what the requirement is for having your file extension as jsx vs js for your components. It did not effect me at all, but I could imagine it could mess with intellisense or snippets.
For me renaming file to babel.config.js worked.
Here is my config file an NX project using next with Typescript along with Twin-macro
// .babelrc.js >> babel.config.js
module.exports = {
presets: [
[
"#nrwl/react/babel",
{
"runtime": "automatic",
"targets": {
"browsers": [">0.25%", "not dead"]
},
"preset-react": {
runtime: "automatic",
importSource: "#emotion/react",
},
}
],
'#babel/preset-env',
'#emotion/babel-preset-css-prop',
'#babel/preset-typescript'
],
plugins: ['#emotion', 'macros', '#babel/plugin-transform-runtime', 'react-docgen'],
}
Also, please note even updating package.json works,
https://kulshekhar.github.io/ts-jest/docs/getting-started/presets/#basic-usage
// package.json
"jest": {
// Replace `ts-jest` with the preset you want to use
// from the above list
"preset": "ts-jest"
}
I encountered the same problem with Typescript, Jest, and VueJS/VueCli 3. The normal build has no problem. only happens for Jest. I struggled for hours by searching. But no answer actually works. In my case, I have a dependency on my own typescript package which I specific "target": "es6" in the tsconfig.json. That's the root cause. So the solution is simply to change the dependent's (Not the same project) back to es5 tsconfig.json:
{
"compilerOptions": {
"target": "es5",
...
},
...
}
Personnaly I followed #ajwl setup but discovered that jsdom-worker inside setupFiles: section of jest.config.js was triggering that same error. Once removed, my tests were passing.
P.S. my babel.config.js is a bit different, since I have a Vuejs (v2) SPA (bundled with Vitejs):
module.exports = {
plugins: ['#babel/plugin-transform-modules-commonjs'],
presets: [['#babel/preset-env', { targets: { node: 'current' } }]]
}
The problem is likely that jest doesn't support esmodules natively. Which can cause problems if youre typescript target is es6 or greater.
If you are testing the built typescript output, you could simply add a module=commonjs flag while transpiling. That way, your code can run with es6 or greater and still work with Jest.
"scripts": {
"test": tsc --module commonjs && jest {your-output-folder}/
}
What's great about this is that I didn't have to add any additional babel dependencies or special jest runners :)
I solved it by changing my tsconfig.json to a compatible native output
"module": "commonjs", /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
It is not ideal in every scenario but you might be okay with this.
All I had to do, was simply updating the package #babel/preset-env in the dev dependencies to the latest version
// package.json
"#babel/preset-env": "^7.18.6"
None of the answers helped me, what did help me was making sure my NODE_ENV was set to test, since babel config is per NODE_ENV using the wrong NODE_ENV by accident that is not configured in babel config will mean you wont be using babel and the typescript files will not be transformed.
It took me couple of hours to figure this one out so i hope it will save someone else the time it took me.
Don't know why and how but how I solved the problem was really interesting.
Just add __mocks__ folder in your src folder and create an empty file inside __mocks__ named axios.js
I discovered that this error might be triggered when you try to load a dependency that is made for the browser and, thus, cannot work with jest (node).
I had a lot of trouble solving this issue for #zip.js/zip.js lib. But I could do it like that:
Here is my jest.config.js. Adapt it to your need. The trick here is the moduleNameMapper that will make all imports to zip.js point to the file __mocks__/#zip.js/zip.js I created in my root folder.
export default {
preset: 'ts-jest',
testEnvironment: 'node',
moduleNameMapper: {
'#zip.js/zip.js': '<rootDir>/__mocks__/#zip.js/zip.js',
},
}
And here is what I have in <rootDir>/__mocks__/#zip.js/zip.js file:
module.exports = {}
Too late for this answer :)
After trying all the possible solutions, this worked for me:
The solution, that works for me:
create a file named jest/mocks/#react-native-firebase/crashlytics.js
export default () => ({ log: jest.fn(), recordError: jest.fn(), });
create a file named jest/jestSetupFile.js
import mockFirebaseCrashlytics from './mocks/#react-native-firebase/crashlytics';
jest.mock('#react-native-firebase/crashlytics', () => mockFirebaseCrashlytics);
in package.json add
"jest": { "setupFiles": ["./jest/jestSetupFile.js"] },
I needed to do a couple things to get this to work for me
Rename my .babelrc to babel.config.js and make a little change:
// .babelrc
{
"presets": [
[
"#babel/preset-env",
{
"corejs": "3.26",
"useBuiltIns": "usage"
}
],
"#babel/preset-react"
],
...
}
// babel.config.js - This still works fine with webpack
module.exports = {
"presets": [
[
"#babel/preset-env",
{
"corejs": "3.26",
"useBuiltIns": "usage"
}
],
"#babel/preset-react"
],
...
}
Add the following to my jest config file:
{
...
"transformIgnorePatterns": [
"node_modules/(?!(react-leaflet-custom-control)/)"
],
...
}
Where react-leaflet-custom-control was the package causing issues for me.
If you're using TypeScript, and you have a tsconfig.json file, try removing "module": "esnext" if you're using it
Running npm ci fixed this problem for me.
I started a multiplatform project with code sharing between react-native and react-js.
So I have a webpack setup for browser/Electron, and a react-native 0.57 setup for Android/iOS.
The problem I'm having right now is the following:
Can't find variable: require
It might be a very bald question, but do I need anything else? I read, that React-native should support require by itself, but couldn't find anything related to this setup yet.
.babelrc
{"presets": ["module:metro-react-native-babel-preset"]}
I'm also using #babel/polyfill and #babel/runtime on browser side, but I wonder if they would interfere.
Got the solution, my .babelrc was okay, but the packager cached the very first wrong one so I had to start the packager as:
react-native start --reset-cache
After looking at below github issue it looks like the issue is caused by corejs option #babel/plugin-transform-runtime, So replace it by #babel/polyfil
https://github.com/facebook/react-native/issues/21048
.babelrc config for ref
{
"presets": [
"module:metro-react-native-babel-preset",
],
"plugins": [
"react-require",
[
"module-resolver",
{
"root": [
"./src",
"./assets"
],
"alias": {
"app": "./src",
"assets": "./assets"
}
}
],
[
"babel-plugin-require-context-polyfill",
{
"alias": {
"app": "./src"
}
}
],
"#babel/plugin-proposal-export-default-from",
"#babel/plugin-proposal-export-namespace-from",
"#babel/plugin-transform-flow-strip-types",
[
"#babel/plugin-proposal-decorators",
{
"legacy": true
}
],
[
"#babel/plugin-proposal-class-properties",
{
"loose": false
}
],
[
"#babel/plugin-transform-runtime",
{
}
],
],
"sourceMaps": true
}
Install Babel polyfill 7 "#babel/polyfill": "^7.0.0"
And import that in App component
import '#babel/polyfill'
It seems that react-native start --reset-cache works.
Here is my test file
// /imports/components/main.test.js
import React from 'react'
import { shallow, mount } from 'enzyme'
import Main from './main'
import TextInput from "/imports/ui/textInput"
...
and the main.js has
// /imports/components/main.js
import { action1 } from "/imports/actions/myAction"
but it throws an error when I run the test, saying
Cannot find module '/imports/actions/myAction' from 'main.js'
If I comment the import './main', same thing happen with importing TextInput. I have no issue with importing modules in node_modules.
How can I tell Jest or webpack to import the component using absolute path from project directory (i.e import Foo from /imports/...)?
Better way to solve relative path import issue, is by creating jsconfig.json file adjacent to package.json file.
{
"compilerOptions": {
"baseUrl": "src"
}
}
then import { action1 } from "actions/myAction"; will work
If you're using Create React App, you can set up the absolute imports path in a jsconfig.json (need to create in a fresh JavaScript template) or tsconfig.json (already created in the TypeScript template) at the root of your project to serve your usage.
Example:
{
"compilerOptions": {
"baseUrl": "src"
},
"include": ["src"]
}
Official docs: https://create-react-app.dev/docs/importing-a-component/#absolute-imports
Another solution is to create an .env file within the root directory of your project.
Within it you will add NODE_PATH=src/
Thats all
Save the file and restart your dev environment in terminal.
Afterwards, you will go through your project and update some import statements accordingly.
My file structure follows exactly the same pattern as yours. To teach Jest into using imports beginning with a /, I use babel-plugin-module-resolver and its handy root option. My .babelrc for Jest looks like this:
{
"presets": ["es2015", "meteor"],
"plugins": [
"transform-class-properties",
"transform-react-constant-elements",
"transform-react-inline-elements",
"transform-react-remove-prop-types",
["module-resolver", {
"root": ["../"],
"alias": {
"react-router-dom": "react-router-dom/umd/react-router-dom.min.js",
"redux": "redux/dist/redux.min.js",
"react-redux": "react-redux/dist/react-redux.min.js"
}
}]
]
}
As I'm using Meteor which customized its root imports, I hide my Jest usage and configuration into a .jest directory at the root of my repository allowing me to have a specific .babelrc without risking conflicts with Meteor's one.
With webpack(v4) and babel, you can provide absolute paths in your directory.
Follow these steps
In your .babelrc file, make this entry for plugins.Make sure you have babel-plugin-root-import in your package.json as well.
"plugins": [
[
"babel-plugin-root-import",
{
"paths": [
{
"rootPathPrefix": "~",
"rootPathSuffix": "./"
},
{
"rootPathPrefix": "#src",
"rootPathSuffix": "src"
},
{
"rootPathPrefix": "#any-other-folder",
"rootPathSuffix": "src/client/../any-other-folder"
}
]
}
]
]
Now if you run into eslint issue, you can add these lines in your eslintrc:
"settings": {
"import/resolver": {
"babel-plugin-root-import": [
{
"rootPathPrefix": "#src",
"rootPathSuffix": "src"
},
{
"rootPathPrefix": "#any-other-folder",
"rootPathSuffix": "src/client/../any-other-folder"
}
]
}
}
Now to make your editor recognize these paths, you can create this entry in jsconfig file.
{
"compilerOptions": {
"baseUrl": ".",
"paths": {
"~/*": ["/*"],
"#src/*": ["src/*"],
"#any-other-folder/*": ["src/client/../any-other-folder/*"] ==> absolute path to any other folder
}
},
"exclude": ["node_modules"]
}
Hope these entries help.
I had jest configs in package.json file (under "jest" key). So I just have added there this row:
"modulePaths": ["<rootDir>/src/"]
And this works for me. I hope it can help somebody else.
I am trying to get my first Jest Test to pass with React and Babel.
I am getting the following error:
SyntaxError: /Users/manueldupont/test/avid-sibelius-publishing-viewer/src/components/TransportButton/TransportButton.less: Unexpected token
> 7 | #import '../variables.css';
| ^
My package.json config for jest look like this:
"babel": {
"presets": [
"es2015",
"react"
],
"plugins": [
"syntax-class-properties",
"transform-class-properties"
]
},
"jest": {
"moduleNameMapper": {
"^image![a-zA-Z0-9$_-]+$": "GlobalImageStub",
"^[./a-zA-Z0-9$_-]+\\.png$": "RelativeImageStub"
},
"testPathIgnorePatterns": [
"/node_modules/"
],
"collectCoverage": true,
"verbose": true,
"modulePathIgnorePatterns": [
"rpmbuild"
],
"unmockedModulePathPatterns": [
"<rootDir>/node_modules/react/",
"<rootDir>/node_modules/react-dom/",
"<rootDir>/node_modules/react-addons-test-utils/",
"<rootDir>/node_modules/fbjs",
"<rootDir>/node_modules/core-js"
]
},
So what am I missing?
moduleNameMapper is the setting that tells Jest how to interpret files with different extension. You need to tell it how to handle Less files.
Create a file like this in your project (you can use a different name or path if you’d like):
config/CSSStub.js
module.exports = {};
This stub is the module we will tell Jest to use instead of CSS or Less files. Then change moduleNameMapper setting and add this line to its object to use it:
'^.+\\.(css|less)$': '<rootDir>/config/CSSStub.js'
Now Jest will treat any CSS or Less file as a module exporting an empty object. You can do something else too—for example, if you use CSS Modules, you can use a Proxy so every import returns the imported property name.
Read more in this guide.
I solved this by using the moduleNameMapper key in the jest configurations in the package.json file
{
"jest":{
"moduleNameMapper":{
"\\.(css|less|sass|scss)$": "<rootDir>/__mocks__/styleMock.js",
"\\.(gif|ttf|eot|svg)$": "<rootDir>/__mocks__/fileMock.js"
}
}
}
After this you will need to create the two files as described below
__mocks__/styleMock.js
module.exports = {};
__mocks__/fileMock.js
module.exports = 'test-file-stub';
If you are using CSS Modules then it's better to mock a proxy to enable className lookups.
hence your configurations will change to:
{
"jest":{
"moduleNameMapper": {
"\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/__mocks__/fileMock.js",
"\\.(css|less|scss|sass)$": "identity-obj-proxy"
},
}
}
But you will need to install identity-obj-proxy package as a dev dependancy i.e.
yarn add identity-obj-proxy -D
For more information. You can refer to the jest docs
UPDATE who use create-react-app from feb 2018.
You cannot override the moduleNameMapper in package.json but in jest.config.js it works, unfortunately i havent found any docs about this why it does.
So my jest.config.js look like this:
module.exports = {
...,
"moduleNameMapper": {
"\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/__mocks__/fileMock.js",
"\\.(scss|sass|css)$": "identity-obj-proxy"
}
}
and it skips scss files and #import quite well.
Backing my answer i followed jest webpack
Similar situation, installing identity-object-proxy and adding it to my jest config for CSS is what worked for me.
//jest.config.js
module.exports = {
moduleNameMapper: {
"\\.(css|sass)$": "identity-obj-proxy",
},
};
The specific error I was seeing:
Jest encountered an unexpected token
/Users/foo/projects/crepl/components/atoms/button/styles.css:1
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){.button { }
^
SyntaxError: Unexpected token .
1 | import React from 'react';
> 2 | import styles from './styles.css';
If you're using ts-jest, none of the solutions above will work! You'll need to mock transform.
jest.config.js
module.exports = {
preset: 'ts-jest',
testEnvironment: 'jsdom',
roots: [
"<rootDir>/src"
],
transform: {
".(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/jest-config/file-mock.js",
'.(css|less)$': '<rootDir>/jest-config/style-mock.js'
},
};
file-mock.js
module.exports = {
process() {
return `module.exports = 'test-file-stub'`;
},
};
style-mock.js
module.exports = {
process() {
return 'module.exports = {};';
}
};
I found this working example if you want more details.
Solution of #import Unexpected token=:)
Install package:
npm i --save-dev identity-obj-proxy
Add in jest.config.js
module.exports = {
"moduleNameMapper": {
"\\.(css|less|scss)$": "identity-obj-proxy"
}
}
Update: Aug 2021
If you are using Next JS with TypeScript. Simply follow the examples repo.
Else you will be wasting days configuring the environment.
https://github.com/vercel/next.js/tree/canary/examples/with-jest
I added moduleNameMapper at the bottom of my package.json where I configured my jest just like this:
"jest": {
"verbose": true,
"moduleNameMapper": {
"\\.(scss|less)$": "<rootDir>/config/CSSStub.js"
}
}