unit-test-service-layer

Mock all injected repository and external client dependencies using Mockito to isolate service-layer business logic, then assert returned results and verify mock interactions and argument values without loading the Spring context.

Verify exact argument values passed to mocked dependencies in Mockito using argument captors, which capture argument instances for detailed assertion and validate complex orchestration workflows within service methods.

Yes, you can test async and reactive service methods using Mockito and JUnit 5 by applying specific patterns to mock reactive flows, verify interactions, and validate exception paths without starting the Spring context.

Test exception paths and retry logic in Java service classes by mocking external clients with Mockito, configuring them to throw exceptions, and verifying that the service method handles errors and retries interactions correctly.

No, unit testing service layers with Mockito does not require a running database or external services. All injected dependencies are mocked to validate behavior deterministically and execute quickly in complete isolation.