Services don’t get injected when using OpenAPI generated interface

When using an openApi generated interface, services don’t get injected in MockMvc tests. Let me show you.

Controller

@RestController
@Slf4j
@RequiredArgsConstructor
public class MyController implements MyApi {
    private final CodeService codeService;

    @Override
    @PutMapping("/path")
    public ResponseEntity<Void> putStuff(@RequestBody @Valid final Stuff stuff) {
        // do stuff
        return ResponseEntity.ok().build();
    }

    @ExceptionHandler(MethodArgumentNotValidException.class)
    private ResponseEntity<ResponseWithError> handleException(final MethodArgumentNotValidException e, HttpServletRequest request) {
        log.error(e.getMessage());

        final ResponseWithError body = new ResponseWithError();
        body.setTimestamp(TimeUtil.getCurrentTimestampString());
        body.setId(UUID.randomUUID().toString());
        body.setMessage(e.getMessage());
        body.setPath(request.getRequestURI());
        body.code(codeService.getErrors(e.getAllErrors()));

        return ResponseEntity.badRequest().body(body);
    }
}

MyApi

@Generated(value = "org.openapitools.codegen.languages.SpringCodegen", date = "2023-11-15T16:01:27.640187200+01:00[Europe/Berlin]")
@Validated
@Tag(name = "stuff", description = "handles stuff")
public interface MyApi {

    default Optional<NativeWebRequest> getRequest() {
        return Optional.empty();
    }


    /**
     * PUT /stuff : creates stuff
     * creates stuff
     *
     * @param stuff (required)
     * @return OK (status code 200)
     * or CREATED (status code 201)
     * or UNAUTHORIZED (status code 401)
     * or BAD REQUEST (status code 400)
     * or INTERNAL SERVER ERROR (status code 500)
     */
    @Operation(
            operationId = "putStuff",
            summary = "creates stuff",
            description = "creates stuff",
            tags = {"stuff"},
            responses = {
                    @ApiResponse(responseCode = "200", description = "OK"),
                    @ApiResponse(responseCode = "201", description = "CREATED"),
                    @ApiResponse(responseCode = "401", description = "UNAUTHORIZED", content = {
                            @Content(mediaType = "application/json", schema = @Schema(implementation = ResponseWithError.class))
                    }),
                    @ApiResponse(responseCode = "400", description = "BAD REQUEST", content = {
                            @Content(mediaType = "application/json", schema = @Schema(implementation = ResponseWithError.class))
                    }),
                    @ApiResponse(responseCode = "500", description = "INTERNAL SERVER ERROR", content = {
                            @Content(mediaType = "application/json", schema = @Schema(implementation = ResponseWithError.class))
                    })
            },
            security = {
                    @SecurityRequirement(name = "bearerAuth")
            }
    )
    @RequestMapping(
            method = RequestMethod.PUT,
            value = "/path",
            produces = {"application/json"},
            consumes = {"application/json"}
    )
    default ResponseEntity<Void> putStuff(
            @Parameter(name = "stuff", description = "", required = true) @Valid @RequestBody Stuff stuff
    ) {
        return new ResponseEntity<>(HttpStatus.NOT_IMPLEMENTED);
    }
}

Test

@WebMvcTest(controllers = {MyController.class}, excludeAutoConfiguration = {SecurityAutoConfiguration.class})
class MyControllerTest {
    @Autowired
    private MockMvc mvc;

    @MockBean
    private CodeService codeService;

    @Test
    void invalidRequest() throws Exception {
        // @GIVEN
        final Stuff stuff = new Stuff();
        stuff.setThings("");

        final String body = new ObjectMapper().writeValueAsString(stuff);

        given(codeService.getErrors(anyList())).willReturn(MY_VALIDATION_ERROR);

        // @WHEN
        mvc.perform(MockMvcRequestBuilders.put("/path")
                                          .contentType("application/json")
                                          .content(body));

        // @THEN
        // Assertions
    }
}

• I’m using Spring-Boot 2.7.12
• CodeService is annotated with @Component
• MyApi is an OpenAPI-generated interface

When executing the test it triggers the exception and runs into the handler. All fine until it hits the line body.code(codeService.getErrors(e.getAllErrors()));. Somehow codeService does not get injected, but – and that’s the thing I don’t unterstand – when I don’t use the generated interface MyApi the codeService gets injected and the test runs as it should.

Can someone please explain, why the service does not get injected when I use the MyApi interface? And is there a way to get the test working with the generated api?

Edit

• It seems the @Validated annotation causes that behaviour. No matter if I annotate the controller directly or use the generated interface. Can someone explain why?

As it was commented by M. Deinum I changed the accessor to public. No it works!