jest-preset-angular

What is jest-preset-angular?

jest-preset-angular is a Jest preset configuration for Angular projects. It simplifies the setup and configuration of Jest for testing Angular applications, providing necessary configurations, transformers, and environment settings.

What are jest-preset-angular's main functionalities?

Setup and Configuration

This feature provides a preset configuration for Jest, making it easier to set up Jest in Angular projects. The code sample shows how to configure Jest to use jest-preset-angular in the Jest configuration file.

module.exports = { preset: 'jest-preset-angular', setupFilesAfterEnv: ['<rootDir>/setup-jest.ts'] };

Transformers

jest-preset-angular includes transformers to handle TypeScript and Angular templates. The code sample demonstrates how to configure Jest to use ts-jest for transforming TypeScript and HTML files.

module.exports = { transform: { '^.+\.(ts|html)$': 'ts-jest' } };

Global Mocks

jest-preset-angular provides global mocks for common Angular dependencies, such as Angular's testing utilities. The code sample shows how to import jest-preset-angular to include these global mocks in your tests.

import 'jest-preset-angular';

Other packages similar to jest-preset-angular

karma

Karma is a test runner for JavaScript that works well with Angular. Unlike jest-preset-angular, which is a Jest preset, Karma is a standalone test runner that can be configured to work with various testing frameworks, including Jasmine and Mocha.

angular-testing-library

angular-testing-library is a set of utilities for testing Angular components. It focuses on testing user interactions and component behavior, similar to jest-preset-angular, but it is not a Jest preset and can be used with different test runners.

ng-mocks

ng-mocks is a library for creating mocks of Angular components, directives, and services. It complements jest-preset-angular by providing additional mocking capabilities, but it is not a preset configuration for Jest.

README

Jest Preset Angular

A preset of Jest configuration for Angular projects.

This is a part of the article: Testing Angular faster with Jest.

Getting Started

These instructions will get you setup to use jest-preset-angular in your project. For more detailed documentation, please check online documentation.

Install using yarn:

yarn add -D jest jest-preset-angular @types/jest

Or npm:

npm install -D jest jest-preset-angular @types/jest

Configuration

In your project root, create setup-jest.ts file with following contents:

import 'jest-preset-angular/setup-jest';

Add the following section:

• to your root jest.config.js

// jest.config.js
module.exports = {
  preset: 'jest-preset-angular',
  setupFilesAfterEnv: ['<rootDir>/setup-jest.ts'],
};

• or to your root package.json

{
  "jest": {
    "preset": "jest-preset-angular",
    "setupFilesAfterEnv": ["<rootDir>/setup-jest.ts"]
  }
}

Adjust your tsconfig.spec.json to be:

{
  "extends": "./tsconfig.json",
  "compilerOptions": {
    "outDir": "./out-tsc/spec",
    "types": ["jest"]
  },
  "include": ["src/**/*.spec.ts", "src/**/*.d.ts"]
}

Angular Ivy

Check out our Angular Ivy guidance

Example apps

We have example apps to provide a basic setup to use Jest in an Angular project.

Built With

• TypeScript - JavaScript that scales
• Angular - The modern web developer's platform
• ts-jest - Jest transformer for TypeScript

Authors/maintainers

• Michał Pierzchała - thymikee
• Ahn - ahnpnl
• Thomas - wtho

See also the list of contributors who participated in this project.

License

This project is licensed under the MIT License - see the LICENSE.md file for details

Changelog

9.0.0 (2021-05-27)

Bug Fixes

• support all node versions >= 12.13.0 (#923) (96782a6), closes #920
• presets: remove moduleNameMapper config (#910) (df482bc), closes #908

Features

• support Jest 27 (#926) (1c761f8)
• config: load zone ESM when running jest in ESM mode (#892) (e03ec19), closes #751
• add exports field to package.json, see https://nodejs.org/api/packages.html#packages_package_entry_points
• presets: add type definition for presets entry point (#801) (e4ff0c0)
• compiler: support ESM (#721) (a2166f8)
• presets: add ESM preset (#723) (b0073b0)
• compiler: use replace-resources AST transformer from Angular (#708) (1b20c19)
• compiler: use downlevel-ctor AST transformer from Angular (#730) (1f964c3)

Performance Improvements

• compiler: reuse cacheFS from jest to reduce file system reading (#679) (f5d9d4b)
• config: set skipLibCheck: true if not defined in tsconfig (#678) (0df3ce1)

BREAKING CHANGES

• Drop support for Angular < 9.0, see https://angular.io/guide/releases#support-policy-and-schedule.
• Drop support for Node.js version 10 since it becomes EOL on 2021-04-30. Required Node version now is >=12.13.0.
• Require Jest 27.
• Users who are using import 'jest-preset-angular' should change to import 'jest-preset-angular/setup-jest'
• transformers: The AST transformers InlineFilesTransformer and StripStylesTransformer are REMOVED and default jest-preset-angular uses AST transformers from @angular/compiler-cli and @ngtools/webpack. One should remove the old transformers from the jest config.
• compiler: jest-preset-angular now switches to default to use its own transformer which wraps around ts-jest to transform codes.

Users who are currently doing in jest config

// jest.config.js
module.exports = {
    // [...]
    transform: {
      '^.+\\.(ts|js|html)$': 'ts-jest',
    },
}

should change to

// jest.config.js
module.exports = {
    // [...]
    transform: {
      '^.+\\.(ts|js|html)$': 'jest-preset-angular',
    },
}

• serializers:: snapshot serializer paths have been changed:
  • 'jest-preset-angular/build/AngularNoNgAttributesSnapshotSerializer.js' is changed to 'jest-preset-angular/build/serializers/no-ng-attributes.
  • 'jest-preset-angular/build/AngularSnapshotSerializer.js' is changed to 'jest-preset-angular/build/serializers/ng-snapshot.
  • 'jest-preset-angular/build/HTMLCommentSerializer.js' is changed to 'jest-preset-angular/build/serializers/html-comment.
• When generating a new project from Angular CLI, by default the tsconfig.json doesn't contain any path mappings hence removing moduleNameMapper from preset will make sure that the preset works in pair with tsconfig.json. Ones who are relying on the value of moduleNameMapper from the preset should create their own moduleNameMapper config manually or via ts-jest util https://kulshekhar.github.io/ts-jest/docs/getting-started/paths-mapping.

If you wish to reuse the old configuration of moduleNameMapper, you can put this into your Jest config

moduleNameMapper: {
  '^src/(.*)$': '<rootDir>/src/$1',
  '^app/(.*)$': '<rootDir>/src/app/$1',
  '^assets/(.*)$': '<rootDir>/src/assets/$1',
  '^environments/(.*)$': '<rootDir>/src/environments/$1',
}

• By default, if skipLibCheck is not defined in tsconfig, jest-preset-angular will set it to true. If one wants to have it as false, one can set explicitly in tsconfig.
• compiler: jest-preset-angular now switches to default to use its own transformer which wraps around ts-jest to transform codes.

Users who are currently doing in jest config

// jest.config.js
module.exports = {
    // [...]
    transform: {
      '^.+\\.(ts|js|html)$': 'ts-jest',
    },
}

should change to

// jest.config.js
module.exports = {
    // [...]
    transform: {
      '^.+\\.(ts|js|html)$': 'jest-preset-angular',
    },
}