Spring Boot does not register HttpMessageConverter during test run

Question

I'm running a Spring Boot app and I've registered a new HttpMessageConverter called CsvCompactVenueHttpMessageConverter, here's the code for it:

@Component
public class CsvCompactVenueHttpMessageConverter extends
    AbstractHttpMessageConverter<Collection<CompactVenue>> {

    public CsvCompactVenueHttpMessageConverter() {
       super(MediaType.valueOf(TEXT_CSV));
    }

   >> message converter implementation code <<
}

It extends AbstractHttpMessageConverter and is registered as a bean on class WebConfiguration:

@Configuration
public class WebConfiguration extends WebMvcConfigurerAdapter {

    @Bean
    public CsvCompactVenueHttpMessageConverter csvCompactVenueHttpMessageConverter() {
        return new CsvCompactVenueHttpMessageConverter();
    }
}

Then I have a rest resource called FoursquareResource:

@RestController
@RequestMapping("/foursquare")
public class FoursquareResource {

    @Autowired
    FoursquareService foursquareService;

    @GetMapping(value = "/{location}", produces = {"application/json", "text/csv"})
    public Collection<CompactVenue> searchVenuesByLocationAndIncreasingRange(@PathVariable String location, @RequestParam(defaultValue = "1") Integer numQueries) throws FoursquareApiException, FoursquareServiceException {
        return foursquareService.searchVenuesByLocationAndIncreasingRange(location, numQueries);
    }
}

When I run the app and call http://localhost:8080/foursquare/New York NY it works fine and renders the text/csv response.

But when running the test with RestAssured and @SpringBootTest I get a HTTP 406 response (because I think it did not register correctly the HttpMessageConverter for text/csv), here's the code:

@RunWith(SpringRunner.class)
@SpringBootTest
@Slf4j
public class FoursquareResourceTest {

    @Mock
    FoursquareService foursquareService;

    @InjectMocks
    FoursquareResource foursquareResource;

    @Before
    public void before() throws Exception {
        CompactVenue venue = new CompactVenue();
        FieldUtils.writeField(venue, "id", "aUfmEW745", true);
        Collection<CompactVenue> venues = new ArrayList<>();
        venues.add(venue);
        when(foursquareService.searchVenuesByLocationAndIncreasingRange(any(), any())).thenReturn(venues);
    }

    @Test
    public void testSearchVenuesByLocationAndIncreasingRangeCsv() throws Exception {
        MockMvcResponse response =
        given().
            accept("text/csv").
            standaloneSetup(foursquareResource).
        when().
            get(String.format("/foursquare/%s?numQueries=%d",location,numQueries)).
        then().
            statusCode(200).
        extract().response();

        log.info(response.body().print());
    }

}

I'm not sure why do I get a right answer when running the Spring Boot app but the 406 error when running as a Test. It looks like the new HttpMessageConverter is not registered on the tests but I can't see why. Thanks and regards.

Answer 1

406 Not Acceptable just means that the controller is not able to serve the representation, requested by the client. In your case the client indicates its capability to read text/csv by sending Accept header, but the controller is not able to send text/csv back. Most probably lacking your converter. To understand why, it is important to understand one thing about MockMvc. It is not clear, how your MockMvc is initialized, but I assume it is standalone setup. Be aware that standaloneSetup creates a new application context, where the beans from you standard configurations are not registered, including your custom converter. This explains, why the code works in a "normal" run, but fails in test. To overcome this, either use webAppContextSetup (which will start the application and embedded Jetty/Tomcat) with injected application context or manually set the converters by calling setMessageConverters on StandaloneMockMvcBuilder. For example,

mockMvc = MockMvcBuilders
        .standaloneSetup(controller)
        .setMessageConverters(new SomeConverter(),
                new SomeOtherConverter())
        .build();

You can then reuse the mockMvc object in your REST Assure just by calling

RestAssuredMockMvc.mockMvc(mockMvc);