Unable to register @RestControllerAdvice Class via WebTestClient [SPR-16520]

[spring-projects-issues]

kabubu opened SPR-16520 and commented

Given rest controller:

@RestController
public class MyController {

    @GetMapping(value = "/errors")
    public Flux<Object> getErrors() {
        return Flux.error(new NumberFormatException());
    }
}

controlleradvice code:

@RestControllerAdvice 
public class GlobalHandler{

    @ExceptionHandler(NumberFormatException.class)
    public ResponseEntity<String> hadleEx(NumberFormatException ex) {
       return ResponseEntity.badRequest().build();
    }
}

and test:

@RunWith(SpringRunner.class)
public class SimpleTest{

    WebTestClient webTestClient;

    @Before
    public void init() {
         webTestClient = WebTestClient
                .bindToController(new MyController())
                .controllerAdvice(GlobalHandler.class)             
                .build();
    }

  @Test
    public void getErrors() {
        this.webTestClient.get().uri("/errors")
                .exchange()
                .expectStatus().isBadRequest();
    }
}

Despite invoking controllerAdvice() method on WebTestClient an @ExceptionHandler located on ControllerAdvice doesnt work and test ends with " No content
< 500 Internal Server Error < Content-Type: [application/json;charset=UTF-8]
Content not available yet"

If we put @ExceptionHandler in @RestController body everything works fine.

---

Affects: 5.0.4

Referenced from: commits bb8cddd, 01d9475

[spring-projects-issues]

Rossen Stoyanchev commented

This is because the @ControllerAdvice is registered as a class, and not as an instance (as expected). Changing it to new GlobalHandler works. I've added assertions to ensure this is flagged with an IllegalArgumentException.

[spring-projects-issues]

kabubu commented

Thank you for help and quick answer! putting assertions there is a good idea.

[spring-projects-issues]

Juergen Hoeller commented

Since we have a test of our own (in the performance profile: see https://build.spring.io/browse/SPR-PERF-JOB1-1286/test/case/179672969) which registered Class instances before (just as a dummy but we still tolerated that registration), I've revised this to turn registered Class arguments into instances on the fly rather than rejecting them... which should usually match the user's intention there.

[spring-projects-issues]

Rossen Stoyanchev commented

Good idea.