An introduction to testing

As we've seen during this chapter's introduction, testing is an essential part of any development workflow and can be divided into three separate testing phases:

• Unit testing: These tests aim to make sure that every single function in your code is working. They do that by testing the codebase's functions individually against correct and incorrect inputs, asserting their results and possible errors to ensure they're working expected.
• End-to-end testing: This testing strategy reproduces a typical user interaction with your application, ensuring that the app responds with a specific output once a given action occurs, just like we would do by testing the website manually on a web browser. For instance, if we build a form, we want to automatically guarantee that it is working correctly, validating the input, and performing a specific action on the form's submission. Also, we want to test that the user interface is rendering...