CombiiningSample.java

package sample;

import java.util.ArrayList;
import java.util.List;
import reactor.core.publisher.Mono;
import reactor.test.StepVerifier;

public class CombiningSample {

  public static void main(String[] args) {
    List<Mono<Boolean>> sources = new ArrayList<>();

    /**
     * Don't use {@link Mono#just}, if you expect execution on subscription time, 
     * instead of assembly time.
     */
    sources.add(Mono.fromCallable(() -> true));
    sources.add(Mono.fromCallable(() -> true));
    sources.add(Mono.fromCallable(() -> false));
    sources.add(Mono.fromCallable(() -> true));
    sources.add(Mono.fromCallable(() -> false));

    Mono<Boolean> finalMono = sources.stream()
        .reduce(Mono.just(true), (previous, next) -> previous.flatMap(value -> value ? next : Mono.empty()));

    /**
     * End with complete signal, without on next.
     */
    StepVerifier.create(finalMono)
        .expectSubscription()
        .expectComplete()
        .verify();

    /**
     * End with false as fallback value.
     */
    StepVerifier.create(finalMono.switchIfEmpty(Mono.just(false)))
        .expectSubscription()
        .expectNext(false)
        .expectComplete()
        .verify();
  }
}