Spring Boot Spring Boot WebFlux and Reactive Programming 3

Question 1

Which Reactor operator blocks the reactive pipeline until the Mono or Flux completes, returning the result synchronously?

Accepted Answer

block()

Answer

subscribe()

Answer

await()

Answer

get()

Question 2

In Spring WebFlux, what is the purpose of `WebTestClient`?

Accepted Answer

A tool for testing reactive WebFlux controllers and endpoints

Answer

A mock WebClient for unit tests without a server

Answer

A load-testing utility for reactive services

Answer

An in-memory HTTP client for integration with MockMvc

Question 3

What does the `switchIfEmpty` operator do in a Reactor pipeline?

Accepted Answer

Subscribes to a fallback publisher when the source completes empty

Answer

Converts a Flux to a Mono when all elements match

Answer

Filters null values from a Flux

Answer

Switches the scheduler when no items are emitted

Question 4

Which interface must a class implement to act as a global exception handler in Spring WebFlux?

Accepted Answer

WebExceptionHandler

Answer

ReactiveExceptionResolver

Answer

GlobalErrorHandler

Answer

WebFluxErrorController

Question 5

How does Spring WebFlux support server-sent events (SSE) in a controller method?

Accepted Answer

By returning Flux> with produces = text/event-stream

Answer

By returning ResponseEntity<SseEmitter>

Answer

By annotating the method with @SseStream

Answer

By configuring sse.enabled=true in application.properties

Question 6

Which Reactor operator is used to log each signal (onNext, onError, onComplete) in a reactive pipeline for debugging?

Accepted Answer

log()

Answer

debug()

Answer

trace()

Answer

inspect()