Testing Reactive Spring Boot Applications with StepVerifier

Reactive programming in Spring Boot offers incredible performance, but testing asynchronous, non-blocking streams requires a completely different mindset and toolset than traditional imperative code. This text-based course guides you through the essential strategies for verifying reactive streams, ensuring your applications remain resilient, fast, and bug-free. You will transition from basic testing concepts to confidently asserting complex publisher behaviors in enterprise environments. What you will learn: Understand reactive stream fundamentals and how publishers like Mono and Flux behave under test; Master StepVerifier to assert values, handle errors, and manipulate virtual time for time-based publishers; Implement mock configurations and slice testing to isolate your reactive web and data layers; Detect accidental blocking calls in your reactive threads using BlockHound; Apply modern testing patterns to verify backpressure and stream cancellation behaviors. We start with the core terminology and foundational concepts of reactive streams before moving into step-by-step written walkthroughs of real-world testing scenarios, including database and web endpoints. This course is designed for Java developers who are new to reactive testing or looking to solidify their understanding of Project Reactor's testing suite. No prior reactive testing experience is required, though a basic familiarity with Spring Boot is helpful. Start reading today to write reliable, non-blocking tests for your Spring Boot applications.