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Angular Testing with Jasmine

Write a Unit Test

Explore writing unit tests for Angular components with Jasmine. Understand how to use TestBed to create isolated test environments, run change detection cycles, and make assertions on component properties and rendered HTML content. This lesson teaches you how to validate component creation and data binding effectively to improve application reliability.

We'll cover the following...

Testing an Angular component

Let’s take a look at the files created when we generate a new component using the Angular CLI. For example, we could use the generate command to create an ArticlesIndex component:

Shell
ng generate component ArticlesIndex

When Angular generates the component, it creates four files:

Javascript (babel-node)
articles-index.component.html
articles-index.component.spec.ts
articles-index.component.ts
articles-index.component.css

Angular generates a basic test for us in articles-index.component.spec.ts. At the end of the file, there is an example test that Angular has written for us. The toBeTruthy method tests that our result is true when interpreted as a boolean. All values are considered to be truthy except for the following falsy values: false, 0, -0, "", null, NAN, and undefined. So, in this case, our component variable will be truthy if it was created successfully.

Javascript (babel-node)
it('should create', () => {
  expect(component).toBeTruthy();
});

Try running your first Angular component test in the code widget below:

Angular component test
Remember that our goal in unit testing is to isolate the component or part of the system that we want to test. In this case, Angular ...