Mocking
Mocking is simply replacing specific functionality in our test with default values. An example of mocking could be to only pretend to make a network call but instead return a hardcoded value. The reason we want to do this is we want to only test a single unit or a small piece of our code. By mocking some portions of our code that are not specific to what we are testing, we are avoiding confusion and making certain our test works consistently. For example, if we were trying to test input in our code, we wouldn't want a network call failure to affect the result of that test, because a network call has nothing to do with the input element specifically. When we want to do end-to-end testing or integration testing, we can worry about the network call as well. But that is a different animal from unit testing (in some teams, integration testing is handled by the QA team separately) and we won't cover it here. Now, when it comes to React components, testing-library actually...