该系列文章翻译自https://www.baeldung.com/mockito-series

下面介绍模拟RestTemplate的两种方式

@Service
public class EmployeeService {

    @Autowired
    private RestTemplate restTemplate;

    public Employee getEmployee(String id) {

    ResponseEntity resp = 

          restTemplate.getForEntity("http://localhost:8080/employee/" + id, Employee.class);

    return resp.getStatusCode() == HttpStatus.OK ? resp.getBody() : null;

    }

}

使用Mockito

@RunWith(MockitoJUnitRunner.class)
public class EmployeeServiceTest {
 
    @Mock
    private RestTemplate restTemplate;
 
    @InjectMocks
    private EmployeeService empService = new EmployeeService();
 
    @Test
    public void givenMockingIsDoneByMockito_whenGetIsCalled_shouldReturnMockedObject() {
        Employee emp = new Employee(“E001”, "Eric Simmons");
        Mockito
          .when(restTemplate.getForEntity("http://localhost:8080/employee/E001", Employee.class))
          .thenReturn(new ResponseEntity(emp, HttpStatus.OK));
 
        Employee employee = empService.getEmployee(id);
        Assert.assertEquals(emp, employee);
    }
}

2. 使用Spring Test

SpringTest模块包含一个名为MockRestServiceServer的mock服务器，当请求传递给RestTemplate时，我们可以设置服务器返回指定的对象。

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = SpringTestConfig.class)
public class EmployeeServiceMockRestServiceServerUnitTest {

    @Autowired
    private EmployeeService empService;
    @Autowired
    private RestTemplate restTemplate;
   
    private MockRestServiceServer mockServer;
    private ObjectMapper mapper = **new** ObjectMapper();

    @Before
    public void init() {
        mockServer = MockRestServiceServer.createServer(restTemplate);
    }

    @Test                                                                                         
    public void givenMockingIsDoneByMockRestServiceServer_whenGetIsCalled_thenReturnsMockedObject()() {   
        Employee emp = new Employee("E001", "Eric Simmons");
        mockServer.expect(ExpectedCount.once(), 
          requestTo(new  URI("http://localhost:8080/employee/E001")))
          .andExpect(method(HttpMethod.GET))
          .andRespond(withStatus(HttpStatus.OK)
          .contentType(MediaType.APPLICATION_JSON)
          .body(mapper.writeValueAsString(emp))
        );                                   

        Employee employee = empService.getEmployee(id);
        mockServer.verify();
        Assert.assertEquals(emp, employee);                                                        
    }
}