According to Uncle Bob, tests are part of the system; many developers think the opposite since they are not deployed. He declares that it is a catastrophic point of view since the test’s role is to support the development and keep the system robust and easy to change. (Clean Architecture, Robert C. Martin, 2018)
In Frontend, it is commonly tested, the interactions of the end users with our application. We should guarantee to our users when they log in, open a pop-up, add a comment or do any other interaction with our apps to not encounter any errors and live undesirable experiences.