@SpringBootTest
@AutoConfigureMockMvc
class UserControllerTest {
    @Autowired
    private MockMvc mockMvc;
 
    @Test
    void shouldReturnUser() throws Exception {
        mockMvc.perform(get("/api/users/1"))
               .andExpect(status().isOk())
               .andExpect(jsonPath("$.username").value("john_doe"))
               .andExpect(header().exists("Content-Type"));
    }
}