Tests are required to verify software functionality in simulated environments. Software tests should run predictably, isolated, reliably, fast, and in an automated way. In order to enable productive project life cycles, it's important to keep tests maintainable.

Unit tests verify the behavior of individual units of an application, mostly single entity, boundary, or control classes. Component tests verify the behavior of coherent components. Integration tests fulfill the need to verify the interaction of the Java EE components. Database integration tests use embedded databases together with standalone JPA to verify the persistence mapping. System tests verify deployed applications that run on actual environments. Container orchestration heavily supports running system test environments with potential mock applications.

In order to verify functionality before it is pushed to the central repository, engineers need the ability to run tests on their local environment. Changes that contain careless mistakes disturb other teammates by unnecessarily breaking the build. Docker, Docker Compose, and Kubernetes can run on local environments as well, enabling developers to verify behavior upfront. It's advisable to craft simple automation scripts that include the required steps.

In order to achieve a constant development velocity, it's required to develop maintainable test cases. In general, test code should have a similar quality to production code. This includes refactoring, proper abstraction layers, and software quality in general.

These approaches are, in fact, more helpful than introducing sophisticated test frameworks using dynamic JVM languages. Whereas frameworks such as Spock certainly enable readable, minimal test cases, the benefits of using proper practices of software craftsmanship have a more positive impact on the overall test code quality, especially once test scenarios become complex. No matter what testing technology is being used, software engineers are advised to mind the test code quality in order to keep test cases maintainable.

The following chapter will cover the topic of distributed systems and microservices architectures.