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Angular Testing Library

Angular Testing Library builds on top of DOM Testing Library by adding APIs for working with Angular components. Starting from ATL version 17, you also need to install @testing-library/dom:

npm install --save-dev @testing-library/angular @testing-library/dom

Or, you can use the ng add command. This sets up your project to use Angular Testing Library, which also includes the installation of @testing-library/dom.

ng add @testing-library/angular

The problem

You want to write maintainable tests for your Angular components. As a part of this goal, you want your tests to avoid including implementation details of your components and rather focus on making your tests give you the confidence for which they are intended. As part of this, you want your testbase to be maintainable in the long run so refactors of your components (changes to implementation but not functionality) don't break your tests and slow you and your team down.

This solution

The Angular Testing Library is a very lightweight solution for testing Angular components. It provides light utility functions on top of DOM Testing Library in a way that encourages better testing practices. Its primary guiding principle is:

The more your tests resemble the way your software is used, the more confidence they can give you.

So rather than dealing with instances of rendered Angular components, your tests will work with actual DOM nodes. The utilities this library provides facilitate querying the DOM in the same way the user would. Finding form elements by their label text (just like a user would), finding links and buttons from their text (like a user would). It also exposes a recommended way to find elements by a data-testid as an "escape hatch" for elements where the text content and label do not make sense or is not practical.

This library encourages your applications to be more accessible and allows you to get your tests closer to using your components the way a user will, which allows your tests to give you more confidence that your application will work when a real user uses it.

The Angular Testing Library:

  • Re-exports the query and fireEvent utility functions from DOM Testing Library.
  • Encapsulates the fireEvent functions of your component to automatically call detectChanges() after an event occurs
  • Is test framework agnostic, it runs on every test framework