[FIXED] Spring Mock Test return null body with CompletableFuture

Issue

i'm trying to make some tests for my rest api but when i start the first test the response body is null and i think it's because i am using CompletableFuture...

@SpringBootTest
@AutoConfigureMockMvc
@ExtendWith(SpringExtension.class)
public class UserControllerTests {

    @Autowired
    private MockMvc mockMvc;

    @InjectMocks
    private UserRestController controller;

    @Test
    @WithMockUser(username = "test", password = "test", roles = "ADMIN")
    public void tryGetAllUsers_shouldFindAllUsers() throws Exception {
        mockMvc.perform(get("/api/v1/user/all").accept(MediaType.APPLICATION_JSON))
                .andExpect(status().isOk())
                .andDo(print());
    }
}

Controller class

@GetMapping("/all")
    @RolesAllowed("ADMIN")
    @ResponseBody
    public CompletableFuture<ResponseEntity<Page<User>>> getUsers(@PageableDefault(sort = "id", direction = Sort.Direction.ASC) Pageable pageable) {
        return CompletableFuture.supplyAsync(() -> ResponseEntity.ok(service.getUsers(pageable)));
    }

I've tried so many ways and asked to so many people but one month later i got no solutions...

Solution

You can make MockMvc to wait for your async response. change the code like this:

public void tryGetAllUsers_shouldFindAllUsers() throws Exception {
    MvcResult mvcResult = mockMvc.perform(MockMvcRequestBuilders.get("/api/v1/user/all")
            .accept(MediaType.APPLICATION_JSON))
            .andExpect(request().asyncStarted())
            .andReturn();

    mockMvc
            .perform(asyncDispatch(mvcResult))
            .andExpect(status().isOk())
            .andDo(print());

}

I

Answered By - hatef alipoor
Answer Checked By - Pedro (JavaFixing Volunteer)