Understanding end-to-end tests

The idea of end-to-end tests is very simple: these tests try to simulate real-world user behavior and verify that the application behaves as expected. Normally, end-to-end tests work as black-box tests.

This means that the testing framework does not know the inner functionality of the application that is being tested. It runs against the release build of the application, which will be shipped.

Understanding the role of end-to-end testing

At first sight, end-to-end tests seem to be a silver bullet for automated testing. Shouldn’t it be enough to simply test all scenarios of our application with end-to-end tests? Do we even need other test types, such as unit tests, integration tests, or component tests?

The answers to these questions are very simple. End-to-end tests are powerful, but they also have some traits that make them only cover certain scenarios very well. First, end-to-end tests run for a long time, so testing all the functionality...