Jest: Failed to parse the TypeScript config file

Question

I'm trying to install Jest for use with Babel and Typescript. I've followed the instructions shown here to the letter but I'm getting:

Error: Jest: Failed to parse the TypeScript config file C:...jest.config.js`

...when I run npm run test.

The contents of jest.config.ts is:

export default {
    //lots of commented-out stuff in here - nothing at all uncommented
}

Here's the exact steps I did:

init project - npm init -y
install Jest - npm -i --save-dev jest
make a script (sum.js) and a test (sum.test.js) file:

sum.js:

function sum(a, b) {
  return a + b;
}
module.exports = sum;

sum.test.js

const sum = require('./sum');
test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});

add test command to package.json:

package.json:

{
  "name": "jest-learn",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "jest"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@babel/core": "^7.17.5",
    "@babel/preset-env": "^7.16.11",
    "@babel/preset-typescript": "^7.16.7",
    "babel-jest": "^27.5.1",
    "jest": "^27.5.1"
  }
}

At this point, if I run yarn test, my test runs and passes just fine. The problem is when I try to introduce Babel and Typescript. Steps continue:

install Babel deps: npm -i --dev babel-jest @babel/core @babel/preset-env
create babel.config.js
install Typescript: npm -i --dev @babel/preset-typescript
add @babel/preset-typescript to babel.config.js:

babel.config.js:

module.exports = {
  presets: [
    ['@babel/preset-env', {targets: {node: 'current'}}],
    '@babel/preset-typescript',
  ],
};

Now when I run npm run test I get the above error. What did I do wrong?

I have same similar issue when I update Jest from 27.5.1 to >=28. Are you sure you have error about .js file, not .ts ? Error: Jest: Failed to parse the TypeScript config file C:...jest.config.js — Артём Игнатьев
– Артём Игнатьев, Commented Aug 30, 2022 at 23:23

nkmuturi · Accepted Answer · 2023-05-12 13:34:56Z

2

This worked for me from Jest docs:

create and add file jest.config.ts to your source directory with content like:

    /** @type {import('jest').Config} */
        const config = {
            verbose: true,
        };
      
    module.exports = config;

Then, make sure to include the file in your tsconfig.json file:

    ...
    "include": ["./src/**/*.tsx", "./src/**/*.ts", "src/jest.config.ts"]

in your packages.json: Ensure also that you have installed jest, ts-jest, and ts-node-dev modules:

    ...
    },
      "devDependencies": {
        "@faker-js/faker": "^7.5.0",
        "@types/express": "^4.17.14",
        "@types/jest": "^29.0.3",
        "@types/uuid": "^8.3.4",
        "jest": "^29.0.3",
        "nodemon": "^2.0.20",
        "ts-jest": "^29.0.2",
        "ts-node-dev": "^2.0.0",
        "typescript": "^4.8.3"
      }

and that the jest transform configuration script looks like:

"jest": {
    "transform": {
      ".(ts|tsx)": "ts-jest"
    },
    "testRegex": "(/__tests__/.*|\\.(test|spec))\\.(ts|tsx|js)$",
    "moduleFileExtensions": [
      "ts",
      "tsx",
      "js"
    ]
  },

edited May 12, 2023 at 13:34

answered Sep 27, 2022 at 8:21

nkmuturi

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2 Comments

Marian Klühspies Over a year ago

why do I need a jest transform config in the package.json, when I have a jest.config.ts file?

Daniel Over a year ago

in latest jest you do not need ts-jest and ts-node-dev, you also do not have to include jest.config.ts to tsconfig.json

koikingu · Accepted Answer · 2024-01-01 23:56:04Z

1

This issue was fixed for me by just installing TS Node.

answered Jan 1, 2024 at 23:56

koikingu

111 bronze badge

1 Comment

Danny P Over a year ago

I already had installed and old version of ts-node library, then I updated it, it's working now. You point me to the right direction. Thanks!

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