f.java

                client.request(HttpMethod.GET, server.actualPort(), "localhost", "/")
                    .onComplete(testContext.succeeding(req -> {
                        req.onComplete(testContext.succeeding(httpClientResponse -> {
                            testContext.verify(() -> {
                                assertThat(httpClientResponse.statusCode())
                                    .isEqualTo(200);
                            });
                            checkpoint.flag();
                        }));
                        try {
                            VertxMessageFactory
                                .createWriter(req)
                                .writeStructured(event, CSVFormat.INSTANCE);
                        } catch (Throwable e) {
                            testContext.failNow(e);
                        }
                        checkpoint.flag();
                    }));