In this chapter, we learned how to test pure functions written in TypeScript using Jest. We simply execute the function with the parameters we want to test, and use Jest's expect function chained with one of Jest's matcher functions, such as toBe, to validate the result.
We looked at how to interact with Jest's test runner, and how to apply filters so that only the tests we are focusing on are executed. We learned that testing React and TypeScript components is more involved than testing pure functions, but Jest and react-testing-library give us a great deal of help.
We also learned how to render a component using the render function, and how to interact with and inspect elements using various functions such as getByText and getLabelByText from react-testing-library.
We learned that we can easily test asynchronous interactions using the waitForElement function...