Controller with a single-line method

CustomerController.java

@RestController
class CustomerController {

    @Autowired
    private CustomerService service;
    
    @PostMapping("/api/customers")
    public void create(@Valid @RequestBody CustomerRequest request) {
        service.save(request);
    }
}

CustomerControllerIntegrationTest.java

import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;

import static org.mockito.Mockito.doNothing;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;

@WebMvcTest(CustomerController.class)
class CustomerControllerIntegrationTest {

    @Autowired
    private MockMvc mockMvc;
    @Autowired
    private ObjectMapper objectMapper;
    @MockBean
    private CustomerService service;

    @Test
    @DisplayName("Cenário de sucesso: Criação de cliente com dados válidos")
    void t1() throws Exception {
        CustomerRequest validRequest = new CustomerRequest("John Doe", "[email protected]");

        // Simula o comportamento do serviço
        doNothing().when(service).save(validRequest);

        mockMvc.perform(post("/api/customers")
                .contentType(MediaType.APPLICATION_JSON)
                .content(objectMapper.writeValueAsString(validRequest)))
                .andExpect(status().isOk());
    }

    @Test
    @DisplayName("Cenário de erro: Campos inválidos no request")
    void t2() throws Exception {
        CustomerRequest invalidRequest = new CustomerRequest("", "invalid-email");

        mockMvc.perform(post("/api/customers")
                .contentType(MediaType.APPLICATION_JSON)
                .content(objectMapper.writeValueAsString(invalidRequest)))
                .andExpect(status().isBadRequest())
                .andExpect(jsonPath("$.errors").exists())
                .andExpect(jsonPath("$.errors.name").value("Name is required"))
                .andExpect(jsonPath("$.errors.email").value("Email is invalid"));
    }

    @Test
    @DisplayName("Cenário de erro: Request vazio")
    void t3() throws Exception {
        mockMvc.perform(post("/api/customers")
                .contentType(MediaType.APPLICATION_JSON)
                .content("{}"))
                .andExpect(status().isBadRequest())
                .andExpect(jsonPath("$.errors").exists());
    }
}

CustomerControllerTest.java

@ExtendWith(MockitoExtension.class)
class CustomerControllerTest {

    @Mock
    private CustomerService service;

    @InjectMocks
    private CustomerController controller;

    @Test
    @DisplayName("Happy-path")
    void t1() {
        // Arrange
        CustomerRequest request = new CustomerRequest();
        request.setName("John Doe");
        request.setEmail("[email protected]");

        // Act
        controller.create(request);

        // Assert
        verify(service, times(1)).save(any(CustomerRequest.class));
    }
}