@GetMapping(value = "/{id}")
    public Mono<Post> get(@PathVariable(value = "id") Long id) {
        return this.posts.findById(id);
    }
@Test
    public void getPostById() throws Exception {
        this.rest
                .get()
                .uri("/posts/1")
                .accept(APPLICATION_JSON)
                .exchange()
                .expectBody()
                .jsonPath("$.title")
                .isEqualTo("post one");

        this.rest
                .get()
                .uri("/posts/2")
                .accept(APPLICATION_JSON)
                .exchange()
                .expectBody()
                .jsonPath("$.title")
                .isEqualTo("post two");
    }