@Test
@TestDescription("입력 값이 잘못되어 있는 경우에 에러가 발생하는 테스트")
public void createEvent_Bad_Request_Wrong_Input() throws Exception {
	EventDto eventDto = EventDto.builder()
		.name("Spring")
		.description("REST API Development with Spring")
		.beginEnrollmentDateTime(LocalDateTime.of(2019, 4, 17, 20, 39))
		.closeEnrollmentDateTime(LocalDateTime.of(2019, 4, 18, 20, 39))
		.beginEventDateTime(LocalDateTime.of(2019, 4, 20, 9, 0))
		.endEventDateTime(LocalDateTime.of(2019, 3, 20, 18, 0))
		.basePrice(1000)
		.maxPrice(200)
		.limitOfEnrollment(100)
		.location("강남역 D2 스타트업 팩토리")
		.build();

	mockMvc.perform(post("/api/events")
			.contentType(MediaType.APPLICATION_JSON_UTF8)
			.content(objectMapper.writeValueAsString(eventDto)))
		.andExpect(status().isBadRequest())
		.andExpect(jsonPath("$[0].objectName").exists())
		.andExpect(jsonPath("$[0].defaultMessage").exists())
		.andExpect(jsonPath("$[0].code").exists());
}

errors를 body담으면 json으로 변환해 주지 않을까?

if (errors.hasErrors()) {
	return ResponseEntity.badRequest().body(errors);
}

커스텀 JSON Serializer 만들기

@JsonComponent
public class ErrorsSerializer extends JsonSerializer<Errors> {

	@Override
	public void serialize(Errors errors, JsonGenerator gen, SerializerProvider serializerProvider) throws IOException {
		gen.writeStartArray();
		errors.getFieldErrors().forEach(e -> {
			try {
				gen.writeStartObject();
				gen.writeStringField("field", e.getField());
				gen.writeStringField("objectName", e.getObjectName());
				gen.writeStringField("code", e.getCode());
				gen.writeStringField("defaultMessage", e.getDefaultMessage());

				Object rejectedValue = e.getRejectedValue();
				if (rejectedValue != null) {
					gen.writeStringField("rejectedValue", e.getRejectedValue().toString());
				}

				gen.writeEndObject();
			} catch (IOException e1) {
				e1.printStackTrace();
			}
		});

		errors.getGlobalErrors().forEach(e -> {
			try {
				gen.writeStartObject();
				gen.writeStringField("objectName", e.getObjectName());
				gen.writeStringField("code", e.getCode());
				gen.writeStringField("defaultMessage", e.getDefaultMessage());
				gen.writeEndObject();
			} catch (IOException e1) {
				e1.printStackTrace();
			}
		});

		gen.writeEndArray();
	}
}