Writing Unit Test Cases with Karma for Angular Components


Welcome to Continuous Improvement, the podcast where we explore ways to enhance your software development practices. I’m your host, Victor, and in today’s episode, we’ll be discussing the importance of writing unit tests for your Angular web app.

Many developers often rush to release their code as quickly as possible, sacrificing proper testing in the process. But today, we’ll make a strong case for why writing unit tests should be an integral part of your development process, even if it means taking a bit more time.

Let’s dive right in. The first compelling reason to write unit tests is their ability to identify issues as early as possible. When multiple teams are working on the same codebase, it’s not uncommon for bugs to inadvertently find their way into the app. By having comprehensive unit tests in place, these bugs can be caught early on, preventing those dreaded middle-of-the-night support calls.

Additionally, unit tests enable you to refactor your code with confidence. Instead of dealing with a monolithic system, you can divide your code into manageable, testable units. This modular approach makes it easier to maintain and enhance your app over time.

Now, some companies have policies in place that mandate a certain level of code coverage, often 80% or higher. Writing unit tests not only helps you meet these requirements, but it also provides assurance that your code is well-tested and reliable.

If you’re new to unit testing, have no fear. Angular makes it easy to get started. Simply run the following command in your project directory:

npm run test

This will open a Chrome browser window at localhost, on port 9876. From there, you can initiate testing by clicking the “Debug” button.

Now, let’s discuss how to write a unit test for a specific piece of code. Imagine you have a login.component.ts file with a login() method that toggles a boolean flag from false to true. To test this functionality, create a file named login.component.spec.ts and write your test cases.

Inside the describe() function, you’ll find the test cases. Each case is within its own it() function. For example, in our case, we want to test if the isLogon flag turns true after the login() method is triggered.

By running the tests, you’ll see that the first test case passes successfully, ensuring that our code functions as expected. Furthermore, if another developer makes changes that impact this functionality, the test will catch it.

It’s important to note that when making API calls during testing, you should avoid calling the actual API. Instead, mock your API call with stub data. This ensures that your tests run consistently, regardless of the state of the actual API.

Remember, unit testing is all about creating reliable, independent tests for individual units of code. By following this practice, you can have confidence in the functionality of your app and prevent regressions during the development process.

Well, that’s a wrap for today’s episode of Continuous Improvement. I hope you’ve gained some insight into the significance of writing unit tests for your Angular web app. Remember, taking the extra time to write tests will pay off in the long run, ensuring a more robust and maintainable codebase.

If you enjoyed this episode, make sure to subscribe to our podcast for more valuable insights on software development best practices. Until next time, I’m Victor, signing off. Happy coding!