MockMVC how to test exception and response code in the same test case

Question

I want to assert that an exception is raised and that the server returns an 500 internal server error.

To highlight the intent a code snippet is provided:

thrown.expect(NestedServletException.class);
this.mockMvc.perform(post("/account")
            .contentType(MediaType.APPLICATION_JSON)
            .content(requestString))
            .andExpect(status().isInternalServerError());

Of course it dosen't matter if I write isInternalServerError or isOk. The test will pass regardless if an exception is thrown below the throw.except statement.

How would you go about to solve this?

Answer 1

If you have an exception handler and you want to test for a specific exception, you could also assert that the instance is valid in the resolved exception.

.andExpect(result -> assertTrue(result.getResolvedException() instanceof WhateverException))

UPDATE (gavenkoa) Don't forget to inject @ExceptionHandler annotated methods to the test context or exception will occur at .perform() instead of capturing it with .andExpect(), basically register:

@ControllerAdvice
public class MyExceptionHandlers {
    @ExceptionHandler(BindException.class)
    public ResponseEntity<?> handle(BindException ex) { ... }
}

with @Import(value=...) or @ContextConfiguration(classes=...) or by other means.

Answer 2

You can get a reference to the MvcResult and the possibly resolved exception and check with general JUnit assertions...

MvcResult result = this.mvc.perform(
        post("/api/some/endpoint")
                .contentType(TestUtil.APPLICATION_JSON_UTF8)
                .content(TestUtil.convertObjectToJsonBytes(someObject)))
        .andDo(print())
        .andExpect(status().is4xxClientError())
        .andReturn();

Optional<SomeException> someException = Optional.ofNullable((SomeException) result.getResolvedException());

someException.ifPresent( (se) -> assertThat(se, is(notNullValue())));
someException.ifPresent( (se) -> assertThat(se, is(instanceOf(SomeException.class))));

Answer 3

You can try something as below -

1. Create a custom matcher

   public class CustomExceptionMatcher extends
   TypeSafeMatcher<CustomException> {
   
   private String actual;
   private String expected;
   
   private CustomExceptionMatcher (String expected) {
       this.expected = expected;
   }
   
   public static CustomExceptionMatcher assertSomeThing(String expected) {
       return new CustomExceptionMatcher (expected);
   }
   
   @Override
   protected boolean matchesSafely(CustomException exception) {
       actual = exception.getSomeInformation();
       return actual.equals(expected);
   }
   
   @Override
   public void describeTo(Description desc) {
       desc.appendText("Actual =").appendValue(actual)
           .appendText(" Expected =").appendValue(
                   expected);
   
   }
   }
   

2. Declare a @Rule in JUnit class as below -

   @Rule
   public ExpectedException exception = ExpectedException.none();
   

3. Use the Custom matcher in test case as -

   exception.expect(CustomException.class);
   exception.expect(CustomException
           .assertSomeThing("Some assertion text"));
   this.mockMvc.perform(post("/account")
       .contentType(MediaType.APPLICATION_JSON)
       .content(requestString))
       .andExpect(status().isInternalServerError());
   

P.S.: I have provided a generic pseudo code which you can customize as per your requirement.

Answer 4

I recently encountered the same error, and instead of using MockMVC I created an integration test as follows:

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@ContextConfiguration(classes = { MyTestConfiguration.class })
public class MyTest {
    
    @Autowired
    private TestRestTemplate testRestTemplate;
    
    @Test
    public void myTest() throws Exception {
        
        ResponseEntity<String> response = testRestTemplate.getForEntity("/test", String.class);
        
        assertEquals(HttpStatus.INTERNAL_SERVER_ERROR, response.getStatusCode(), "unexpected status code");
        
    }   
}

and

@Configuration
@EnableAutoConfiguration(exclude = NotDesiredConfiguration.class)
public class MyTestConfiguration {
    
    @RestController
    public class TestController {
        
        @GetMapping("/test")
        public ResponseEntity<String> get() throws Exception{
            throw new Exception("not nice");
        }           
    }   
}

this post was very helpful: https://github.com/spring-projects/spring-boot/issues/7321

Answer 5

In your controller:

throw new Exception("Athlete with same username already exists...");

In your test:

    try {
        mockMvc.perform(post("/api/athlete").contentType(contentType).
                content(TestUtil.convertObjectToJsonBytes(wAthleteFTP)))
                .andExpect(status().isInternalServerError())
                .andExpect(content().string("Athlete with same username already exists..."))
                .andDo(print());
    } catch (Exception e){
        //sink it
    }