How to test the error output of a Spring Boot Controller? - json

Question

I have implemented a simple controller with a simple request / response.
Controller
#RestController
#RequestMapping("/")
public class HelloWorldController extends AbstractRestController {
#RequestMapping(value = "/hello", method = RequestMethod.POST)
public HelloWorldResponse sayHello(#Valid #RequestBody HelloWorldRequest request) {
String message = String.format("Hello %s!", request.getSayHelloTo());
return new HelloWorldResponse(message);
}
}
Request
public class HelloWorldRequest {
#NotEmpty
#NotNull
private String sayHelloTo;
protected HelloWorldRequest() {
}
public HelloWorldRequest(String sayHelloTo) {
this.sayHelloTo = sayHelloTo;
}
public String getSayHelloTo() {
return sayHelloTo;
}
#Override
public String toString() {
return "HelloWorldRequest{" +
"sayHelloTo='" + sayHelloTo + '\'' +
'}';
}
}
When i want to test the correct output for the default error handling i seem to be unable to check the output of the default json format using a unit test. The response always seems to be empty. When i fire the request via a normal curl command is see a correct response. I assume this is because the returned JSON cannot be mapped on the HelloWorldResponse. Is there any way of checking if the returned output is valid on the response body?
Test
class TestSpec extends Specification {
MockMvc mockMvc
def setup() {
mockMvc = MockMvcBuilders.standaloneSetup(new HelloWorldController()).build()
}
def "Test simple action"() {
when:
def response = mockMvc.perform(post("/hello")
.contentType(MediaType.APPLICATION_JSON)
.content('{"sayHelloTo": ""}')
)
then:
response.andExpect(status().isOk())
}
}
Json Response
{
"timestamp" : 1426615606,
"exception" : "org.springframework.web.bind.MissingServletRequestParameterException",
"status" : 400,
"error" : "Bad Request",
"path" : "/welcome",
"message" : "Required String parameter 'name' is not present"
}

Answer 1

try to debug with print() method, may be exception is thrown during execution.
MvcResult andReturn = mockMvc.perform(get("/api")
.accept(MediaType.APPLICATION_JSON))
.andDo(print())
.andReturn();

Answer 2

The #Controller class you posted and the Test case (and response) don't seem to match (you're calling /hello in your test case and your #RequestMapping says /welcome ... Can we see the correct code? It looks like you have a #RequestParam("name") set, but you're not passing it.