如何使用 Mockito 模拟内部类实例

Posted 2023-02-26

【中文标题】如何使用 Mockito 模拟内部类实例

【英文标题】：How to mock Inner class instance using Mockito

【发布时间】：2021-12-24 00:49:55

【问题描述】：

@ConfigurationProperties(prefix= 'app')
@Getter @Setter
public class AppConfig
    private ExternalService externalService=new ExternalService();

    @Getter @Setter
    public static class ExternalService
    private String url;
    private String authToken;
    

我使用 AppConfig 的服务。

@Service
@AllArgsConstructor
    public class ExternalService
    private final AppConfig appConfig;

    public boolean isAuthorize(String token)
        String authUrl=appConfig.getExternalService().getUrl();
        boolean isAuthorize= //External Apis call
        return isAuthorize;
    

ExternalService 的测试类

@ExtendWith(MockitoExtension.class)
class ExternalTestService

    @Mock
    private AppConfig AppConfig;
    
    @Mock
    private AppConfig.ExternalService externalSeriveConfig;

    @InjectMocks
    private ExternalService externalService;

    @Test
    public void shouldAuthorize()
    //Null Pointer exception for AppConfig.getExternalService() 
    Mockito.when(AppConfig.getExternalService().getUrl()).thenReturn("123456");
    Assertions.assertEquals(externalService.isAuthorize(),true);

如果我在 shouldAuthorize 中模拟 GradingProperties.CentralServiceConfig 那么它工作正常但在 ExternalService 的 Assertions.assertEquals 时得到 NullPointerException(String authUrl=appConfig.getExternalService().getUrl();) 喜欢

@Test
public void shouldAuthorize()
    AppConfig.ExternalService externalMock=Mockito.mock(AppConfig.ExternalService.class);
    
    Mockito.when(externalMock.getUrl()).thenReturn("123456");
    Assertions.assertEquals(externalService.isAuthorize(),true);

如何模拟并使这段代码可运行

【参考方案1】：

当你有一个链式方法调用时，你需要确保链式调用的每一部分都返回非空结果。

Mockito.when(AppConfig.getExternalService().getUrl()).thenReturn("123456");

您没有对 AppConfig 的任何调用存根，因此 AppConfig.getExternalService() 返回 null。

你需要：

Mockito.when(AppConfig.getExternalService()).thenReturn(externalSeriveConfig);
Mockito.when(AppConfig.getExternalService().getUrl()).thenReturn("123456");

或者，甚至更好：

Mockito.when(AppConfig.getExternalService()).thenReturn(externalSeriveConfig);
Mockito.when(externalSeriveConfig.getUrl()).thenReturn("123456");