I have the following method I am trying to test (simplified version, but problem is reproducible):

    protected Mono<String> executeRequest(String url) {
        return webClient.method(HttpMethod.GET)
                .uri(url)
                .retrieve()
                .bodyToMono(String.class)
                .doOnError(t -> log.info("Damn, error: {}", t.getMessage()))
                .retryWhen(Retry.backoff(5, Duration.ofSeconds(5)));
    }

This is the test method:

    @Test
    void test() {
        String mockWebServerUrl = mockWebServer.url("/path")
                .uri()
                .toString();

        mockWebServer.enqueue(MockWebServerUtil.createMockResponse(HttpStatus.NOT_FOUND));
        mockWebServer.enqueue(MockWebServerUtil.createMockResponse(HttpStatus.NOT_FOUND));
        mockWebServer.enqueue(MockWebServerUtil.createMockResponse(HttpStatus.NOT_FOUND));
        mockWebServer.enqueue(MockWebServerUtil.createMockResponse(HttpStatus.NOT_FOUND));
        mockWebServer.enqueue(MockWebServerUtil.createMockResponse(HttpStatus.NOT_FOUND));
        mockWebServer.enqueue(MockWebServerUtil.createMockResponse(HttpStatus.NOT_FOUND));


        StepVerifier.withVirtualTime(() -> dumbClass.executeRequest(mockWebServerUrl))
                .expectSubscription()
                .thenAwait(Duration.ofDays(100))
                .expectError()
                .verify();
    }

(the thenAwait(Duration.ofDays(100) is simply to ensure that the retries will for sure finish within the virtual time advance)

I did some debugging and got to the conclusion that if instead of Retry.backoff(5, Duration.ofSeconds(5)) I use Retry.max(5) the test passes. However, if I use either Retry.backoff or Retry.fixedDelay only the first two retries get triggered.

I also saw the accepted answer here but it seems way too complicated for such a simple thing.

Any ideas?