The term system tests is sometimes also used ambiguously. In this context, the term covers all test cases that run the application or the system as a whole, verifying use cases in an end-to-end manner. Sometimes the terms acceptance or integration tests are used respectively. However, this book consistently uses the term system tests to refer to end-to-end tests.

System tests are quite important to verify that a deployed application works as expected, including both business logic and technical concerns. Whereas the majority of business logic should already be covered by unit and component tests, system tests verify that the overall behavior, including all external systems, is met. This includes how functionality is integrated and interacts within the system landscape.

For an application to provide value, it is not sufficient to only include business logic, but also how that logic is accessed. This needs to be verified in an end-to-end manner.

Since this book is targeted for backend applications, UI level tests are not considered here; this includes UI end-to-end tests as well as UI reactiveness tests. Developers typically develop UI tests using test technology such as Arquillian Graphene. The system test approaches described in this chapter are applicable to UI level tests as well.