So let us say we have something like:

public class SomeService {
...
public Flux<String> getStringsFromWebServer() {
  return webClient.get()
      .uri(this::generateSomeUrl)
      .retrieve()
      .bodyToMono(SomePojo.class)
      .map(SomePojo::getStringList)
      .flatMapMany(Flux::fromIterable);
}

Does it make sense to write tests that look like this:

void getStringsFromWebServer_shouldParseInOrderOfReceivingStrings() {
  // given
  // I have mocked up a WebClient, that is wired up to a Mocked Web Server
  // I am preloading the Mocked Web Server with this JSON
  String jsonStrings = "{'stringList': ['hello1', 'hello2', 'hello3']}"
  mockWebServer.enqueue(new MockResponse().setResponseCode(200))
      .addHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
      .setBody(jsonStrings);

  // when
  Flux<String> result = someService.getStringsFromWebServer();

  // then
  StepVerifier.FirstStep<String> fluxStep = StepVerifier.create(result);
  for (int i = 1; i < 4; i  ) {
    String expectedInput = String.format("hello%d", i);
    fluxStep.assertNext(someString -> assertEquals(expectedInput, someString));
  }
  fluxStep.verifyComplete(); 
}

Is this how you are to programmatically assert the order that comes back out from Flux?

Am I doing something bad with the assertNext flux method? I mean in this sense, I am always providing ordered data so I am assuming that fromIterable will consuming from that list in the order that it is received by the spring boot application.

It feels like I am violating some sort of principle here...I mean it works...

CodePudding user response：

Meh sorted it out.

So there is the expectNext method:

https://www.baeldung.com/flux-sequences-reactor

Where you can pregenerate your list and then assert something like this:

List<String> expectedStrings = Arrays.asList(
  "hello1", "hello2", "hello3"
);
...
StepVerifier.create(result)
  .expectNextSequence(expectedStrings)
  .verifyComplete();

EDIT: apparently I have to wait a few days before I can mark my own question as answered?