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Introduction: What is Test Coverage, and Why is it Important?

We all know tests are crucial, but how many should you write? Should you aim for 100% coverage or just focus on critical parts? While there’s no definitive answer, tracking your codebase’s test coverage percentage is a valuable guide. Think of it like monitoring your weight: you don’t have to step on the scale every day, but it helps to check in occasionally to ensure you’re on track.

I learned a lot from taking the Elixir for Programmers course by Dave Thomas, and after completing I wanted to summarize some of my most important takeaways. I especially want to focus on the architecture of the hangman game he creates as an example, as well as the tools used from Erlang’s Open Telecom Platform (OTP). This course shows the power of Elixir in its ability to create highly scalable, fault-tolerant applications.

In this article I’ll go over how to upgrade Testing Library’s user-event package to version 14. I’ll give a brief refresher on why we use user-event in the first place, take a look at what’s new in version 14, and finally go over the details of how I did the upgrade. I’ll include a couple examples of tests that broke when upgrading that will hopefully help make your transition smoother.