如何在Java Spring Boot中模拟RestTemplate？

Question

我试图使用下面的代码模拟resttemplategetEntity()方法，但我得到了异常，而且我是单元测试的新手

public List<SampleObject1> getGitHubUSersList(){

        try {
            ResponseEntity<SampleObject1[]>responseEntity = restTemplate.getForEntity("https://api.github.com/users", SampleObject1[].class);
            List<SampleObject1>arrayList  = Arrays.asList(responseEntity.getBody());
            System.out.println("final list is---->"+objectMapperl.writeValueAsString(arrayList));
            return arrayList;
        }catch (Exception e) {
           e.printStackTrace();
        }
        return null;
    }

public class SampleServiceTest1 {

    @Mock
    RestTemplate mockrestTemplate;

    @InjectMocks
    @Spy
    SampleService1 sampleService;

    @Before
    public void setup() {
    MockitoAnnotations.initMocks(this);
    }

@SuppressWarnings("unchecked")
@Test
public void getGitHubUSersListTest() {

    List<SampleObject1> sampleObject1s = new ArrayList<>();

    SampleObject1 sampoleObject1 = new SampleObject1();
    sampoleObject1.setId(1);
    sampoleObject1.setLogin("sample1");
    sampoleObject1.setNode_id("sample2");
    sampleObject1s.add(sampoleObject1);

    SampleObject1 sampoleObject2 = new SampleObject1();
    sampoleObject2.setId(2);
    sampoleObject2.setLogin("sample3");
    sampoleObject2.setNode_id("sample4");
    sampleObject1s.add(sampoleObject2);

    Mockito.doReturn(sampleObject1s).when(mockrestTemplate).getForEntity(Matchers.anyString(),  ArgumentMatchers.any(Class.class));

    List<SampleObject1> list = sampleService.getGitHubUSersList();

    assertNotNull(list);
}

org.mockito.exceptions.misusing.NullInsteadOfMockException: 
Argument passed to when() is null!
Example of correct stubbing:
    doThrow(new RuntimeException()).when(mock).someMethod();
Also, if you use @Mock annotation don't miss initMocks()
    at com.example.microservice.service.SampleServiceTest1.getGitHubUSersListTest(SampleServiceTest1.java:50)

Answer 1

您的模拟设置是错误的GetForEntity不返回列表 ，因此您不能将其设置为返回，您需要返回ResponseEntity 。

所以为了解决你的问题。声明一个新的模拟

@Mock
private ResponseEntity<SampleObject1[]> mockResponseEntity

doReturn(mockResponseEntity).when(mockrestTemplate).getForEntity(anyString(),  any(Class.class));
doReturn(new SampleObject1[]{sampoleObject1, sampoleObject2}).when(mockResponseEntity).getBody();