Building Event-Driven Microservices

Chapter 15. Testing Event-Driven Microservices

One of the great things about testing event-driven microservices is that they’re very modular. Input to the service is provided by event streams or by requests from a request-response API. State is materialized to its own independent state store, and output events are written to a service’s output streams. Microservices’ small and purpose-built nature make them far easier to test than larger and more complex services. There are fewer moving parts, a relatively standard methodology of handling I/O and state, and plenty of opportunity to reuse testing tooling with other microservices. This chapter covers testing principles and strategies, including unit testing, integration testing, and performance testing.

General Testing Principles

Event-driven microservices share the testing best practices that are common to all applications. Functional testing, such as unit, integration, system, and regression testing, ensures that the microservice does what it is supposed to and that it doesn’t do what it should not do. Nonfunctional testing, such as performance, load, stress, and recovery testing, ensures that it behaves as expected under various environmental scenarios.

Now, before going much further, it’s important to note that this chapter is meant to be a companion to more extensive works on the principles and how-tos of testing. After all, many books, blogs, and documents have been written on testing, and I certainly can’t cover testing ...