Unit Testing in Angular 9: A Comprehensive Guide

Unit testing is an essential practice in Angular development, ensuring that components, services, and other parts of the application work as expected. Angular provides a robust suite of testing tools and libraries, such as Jasmine, Karma, and the Angular Testing Library, that integrate seamlessly into the development workflow. The Angular CLI also supports the setup and execution of tests out of the box.

1. Setting Up the Testing Environment

When we create an Angular project using Angular CLI, the testing environment is automatically set up. This includes the following tools:

• Jasmine: A behavior-driven development framework for testing JavaScript code.

• Karma: A test runner that runs Jasmine tests in the browser.

• Angular TestBed: A utility that configures and initializes an Angular module for unit tests.

For more detailed setup instructions, refer to the official documentation:

• Testing Angular Applications

2. Running Tests

To run the tests, follow these steps in your terminal:

1. Remove the node_modules folder and package-lock.json file.

2. Verify the Node.js version. It should be v14.21.3.

3. Run the following command:

   npm i

4. Once the installation is successful, execute:

   ng test

This will run Karma and launch the tests in the browser. The test results will be displayed in the terminal or browser console, providing immediate feedback on the test outcomes.

If You Encounter below Errors:

Open

Fix:

Error:

Open

Fix:
Run the following command in VS code terminal and retry:

3. Jasmine Syntax and Utilities for Unit Testing in Angular

For more comprehensive information on Jasmine syntax and utilities used in Angular unit testing, refer to the dedicated page:

• Jasmine Syntax and Utilities for Unit Testing in Angular

4. Structure of a Component for Unit Testing in Angular

The structure of a component has a significant impact on the ease with which it can be unit tested. This document provides insights into how to structure Angular components to make them easier to test:

• Structure of Component for Unit Testing in Angular

5. Angular Unit Testing Examples

For practical examples of Angular unit tests, refer to the following page:

• Angular Unit Testing Examples

6. Unit Testing for NGRX Store

If your Angular application uses NGRX for state management, you will need to test NGRX store interactions in your unit tests. This guide provides a comprehensive approach to unit testing for NGRX:

• Unit Testing for NGRX Store

7. Team Shared Mock Setup and Usage Guide

In Angular unit testing, mocking dependencies is an important part of testing components in isolation. To help you get started with mocking in your tests, refer to the shared mock setup guide used by the team:

• Unit Testing: Team Shared Mock Setup and Usage Guide

8. Common Testing Errors and Fixes

As with any testing framework, you may encounter common errors while working with Angular unit tests. Understanding these errors and how to fix them is crucial for writing effective tests. To learn more about common issues and their solutions, refer to the guide on unit testing errors:

• Unit Testing: Common Angular Testing Errors and Fixes

Official Documentation Links

Here are some helpful links to the official documentation for the tools involved in Angular unit testing:

• Testing Angular Applications

• Karma Documentation

• Jasmine Documentation

Conclusion

Unit testing is an essential practice in Angular development, ensuring that components, services, and other parts of our application work as expected. Angular provides powerful testing tools like TestBed, Jasmine, and Karma that integrate seamlessly into our development workflow. By writing unit tests, we can increase the reliability and maintainability of our application.

User Story: https://auperator.atlassian.net/browse/PLAT-2088