How to configure Jest for unit testing in an Angular application

How to configure Jest for unit testing in an Angular application

Jest is a popular testing framework. It is a great alternative to Karma and Jasmine. Learn how to configure Jest in your Angular application.

Today, we will learn how to configure Jest in an Angular application. Angular application by default comes with Karma/Jasmine for unit testing so we need to follow some steps to configure Jest in our applications.

What is Jest?

Jest is a popular test framework for JavaScript.

Why Jest?

Let's understand first Why should we even bother to use Jest?

  • It is really fast.
  • Executes test from the terminal. No need for the browser to run.
  • Offers inbuilt codeCoverage

Uninstall Karma & Jasmine

Before installing Jest, uninstall Karma and Jasmine from your project

npm uninstall karma karma-chrome-launcher karma-coverage-istanbul-reporter karma-jasmine karma-jasmine-html-reporter

Install Jest

npm install jest @types/jest jest-preset-angular --save-dev

Set up Jest in the project

  • Remove karma.conf.js and src/test.ts
  • Create a setupJest.ts file in the root and import 'jest-preset-angular/setup-jest'; inside of it.

Configuration at the end of package.json

Add the following configuration at the end of the package.json file

  "jest": {
    "preset": "jest-preset-angular",
    "setupFilesAfterEnv": [
    "testPathIgnorePatterns": [
    "globals": {
      "ts-jest": {
        "tsconfig": "<rootDir>/tsconfig.spec.json",
        "stringifyContentPathRegex": "\\.html$"

Modify tsconfig.spec.json

Add jest in the compiler options

  "extends": "./tsconfig.json",
  "compilerOptions": {
    "outDir": "./out-tsc/spec",
    "types": [
  "files": [
  "include": [

Remove test block from angular.json

"test": {
          "builder": "@angular-devkit/build-angular:karma",
          "options": {
            "main": "src/test.ts",
            "polyfills": "src/polyfills.ts",
            "tsConfig": "tsconfig.spec.json",
            "karmaConfig": "karma.conf.js",
            "inlineStyleLanguage": "scss",
            "assets": [
            "styles": [
            "scripts": []


If you encounter the following warning then add "allowSyntheticDefaultImports": true in tsconfig.json

ts-jest[config] (WARN) message TS151001: If you have issues related to imports, you should consider setting `esModuleInterop` to `true` in your TypeScript configuration file (usually `tsconfig.json`). See for more information.

Finally! Execute the tests

Tests should be successful in the terminal

Screenshot 2022-07-28 at 8.17.22 PM.png

Github repo for reference

Angular Jest Demo

Thank you for reading!

If you want have any comments or want to reach out to me, please feel free to follow me on Twitter or LinkedIn