Many applications have some sort of user interface, typically a web page or mobile app. These sets of tests validate the system as an end user would use it. In a way, these tests are related to integration tests, but are generally applicable for the facade-level services that directly interact with the clients (apps, web pages, and so on). The test cases are derived from the requirements (user stories) and try out all scenarios that the user would experience on the real app. These tests are generally run with the backend services in the stage environment.

There are many frameworks, such as Selenium, that help in automating these tests. We will not go into detail here as they are outside the scope of this book.