When you create your React application using create-react-app, you're ready to run tests right away. In fact, as part of the boilerplate code that's created for you, a unit test for the App component is created. This test is added so that Jest will find a test that it can run. It doesn't actually test anything meaningful in your application, so you'll probably delete it once more tests are added.
Additionally, create-react-app adds the appropriate script to your package.json file to run your tests. You can just run the following command in your Terminal:
This will actually invoke the test script from react-scripts. This will invoke Jest, which runs any tests that it finds. In this case, since you're ...