How would I test a no events yet logic with from RxJava with Project Reactor Stepverifier?

I'm currently trying to figure out, how to do a similar test in Project Reactor.
Basically I want to ensure that before connect no events occur.

@Test
void connectable() {
Observable<String> provider = Observable.just("Test1", "Test2");
ConnectableObservable<String> connectable = provider.publish();
TestObserver<String> testSubscriber = connectable.test();
testSubscriber.assertEmpty();
connectable.connect();
testSubscriber.assertResult("Test1", "Test2").assertComplete();
}


This is my current attempt, but it is not correct, how would I get this to work?

@Test
void connectable() {
Flux<String> provider = Flux.just("Test1", "Test2");
ConnectableFlux<String> connectable = provider.publish();
FirstStep<String> tester = StepVerifier.create(connectable).expectNoEvent(Duration.ofMinutes(1));
connectable.connect();
tester.expectNext("Test1", "Test2").expectComplete().verify();
}


1 Answer
1

You're almost there. StepVerifier tests the sequence as a whole and you cannot add imperative assertions in the middle. But you can make your assertions and state-modifying calls within the StepVerifier! For that, use then(Runnable):

StepVerifier

StepVerifier

then(Runnable)

@Test
public void stepVerifierTestConnect() {
Flux<String> provider = Flux.just("Test1", "Test2");
ConnectableFlux<String> connectable = provider.publish();

StepVerifier.create(connectable)
.expectSubscription() //expectNoEvent counts the subscription as an event
.expectNoEvent(Duration.ofSeconds(3))
.then(connectable::connect)
.expectNext("Test1", "Test2")
.expectComplete()
.verify();
}


Note the expectSubscription first. This avoid expectNoEvent from blowing up because it considers the act of subscribing as an event (and there is still a subscription to the ConnectableFlux itself - it just prevents subscription to its own upstream until you call connect()).

expectSubscription

expectNoEvent

ConnectableFlux

connect()

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