Complete Guide on Unit Testing for Angular Apps

Complete Guide on Unit Testing for Angular Apps

Angular, an application design framework, is used for developing complex, high-performance single-page apps. Angular unit tests all parts of your code to detect issues like coding errors, bad logic, or malfunctioning features.

There are numerous benefits of Angular testing:

  • It allows you to detect bugs early before they lead to problems
  • This testing makes it simpler to make modifications to your code
  •  It helps ensure that your code is stable

Unit testing can be challenging to achieve for complex development projects. Angular allows you to write code in a simple way. If you plan for unit testing and follow the best practices of Angular coding, it is advisable to add unit tests to your apps. In this article, you’ll look at how to test Angular apps. Let’s start with unit testing.

Unit tests allow web developers to be more confident while modifying code. Dedicated and experienced developers result in high-quality code.

The process of performing unit tests consists of the following steps:

Create Test Cases: Write multiple test cases of an app’s components

Review and Re-write: Review the test cases and re-write them if there are any errors

Baseline: Check whether each code line is in a proper manner or not

Execution: Perform execution using Selenium Grid

Why Do You Need Unit Testing?

  • Performing unit testing allows you to fix bugs immediately
  • Running unit tests provides you with better-quality code
  • It also allows refactoring which means you can modify the code in an error-free way
  •  Unit tests are super-fast and able to simulate all error conditions
  • Useful in Extreme Programming methodology

Why Unit Test Angular Applications?

Angular unit testing enables you to test your app for coding errors and user behavior. Testing these behaviors can be inefficient, but generating tests in your application will help detect problems. One of the best ways to test the app is to create a test for each block. This will help you easily detect bugs and fix them in a timely manner in the development process.

End-to-End Testing

In addition to unit testing, you also need to perform end-to-end testing. This testing verifies the functionality of an app. From loading the page to submitting a form, this includes everything.

There are a few different Angular performance testing tools you can use for this type of testing. But Protractor is one of the best options for Angular. This tool was designed explicitly for this testing of Angular apps. It is easy to use and has several features that make it perfect for end-to-end testing.

When you’re performing this type of testing, it is important to keep a few things in mind. You need to make sure that you are testing the entire application, not just individual pieces. Then you need to test the app from the user’s perspective.

Basics of Angular Component Testing

Angular component testing is the process of checking the performance of application components. You can test Angular components manually by running the application. But, manual testing is time-consuming and impractical for complex applications. You’ll need to find a better way to test Angular components.

  • The basic building blocks of Angular are clubbed into NgModules that collect related code into functional sets.
  • These components define views, changed according to program logic and data.
  • They also use services that provide specific functionality, making the Angular code reusable.
  • Each component has an HTML template that declares how that particular component renders. You can define this template either inline or by using the file path.
  • As the Angular app extends HTML with additional syntax, you can add dynamic values from your component.
  • Any Angular app always has one root module that allows bootstrapping. You can write more flexible code using this application.

How to carry out successful Angular testing?

For performing successful Angular testing, testers need to:

  • Understand the types of tests they need to perform i.e. unit tests and end-to-end tests for Angular apps.
  • Learn all the important testing concepts to produce a higher-quality Angular product.
  • Build more reliable test suites that identify and resolve bugs early in the testing lifecycle.

LEGO blocks of an Angular application

Angular apps are based on the following concepts:

Modules- A Module in an Angular app, is a TypeScript file, where developers can declare the components and service classes and can import other modules of the app.

Components- These are the basic building blocks of an Angular app. It includes templates, Directives, and Pipes.

Services- Angular services are defined to deal with external data and to carry out processing logic independent of user views.

Routing- Used to outline navigation in an Angular app.

These are the LEGO blocks of an Angular app, which allow a web developer to create a responsive and reliable Single Page Application.

How to Do Unit Testing in Angular?

There are numerous things that a component can perform. We must make sure that all these behaviors are considered while writing tests for components:

  • Angular components can render templates into HTML DOM tree
  • These components can talk to services
  • These components can bind data and enable users to update it
  • Angular components can accept data using inputs and emit data using outputs from parent components

Unit Testing with Jasmine and Karma Frameworks for Angular Apps

Jasmine, a free and open-source Behavior Driven Development framework, supports BDD and can run on any JavaScript-enabled platform. It describes tests in a human-readable form. This framework does not require DOM.

Jasmine is ideal for front-end testing. It includes testing the user interface across several devices with different resolutions. Jasmine has wide community support and inclusive documentation which makes it easy to use.

Karma allows the users to execute their Jasmine test codes in multiple browsers from the command line. This command line also displays the test result. It checks the files for modifications and re-runs the tests automatically. This framework handles the process of creating HTML files, opening browsers, and running the tests.


In simple words, testing plays an important part in the development process. Unit testing is necessary and there are different tools you can use for testing. We have shared a few options for Angular testing.

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