RestTemplate 的模拟是用 spring boot 2.x 抛出空指针异常

Question

我正在为调用 REST 后端服务和 MongoDB 的服务层编写单元测试。但是，当在本地执行我的测试时工作正常，但是在编译期间将我的应用程序打包到我的 CICD 管道中时，它会尝试运行单元测试，同时在使用 RestTemplate 和 MongoTemplate bean 时会出现空指针异常。

MyTestService {

    @Autowired
    private RestTemplate restTemplate;

    @Autowired
    private MongoTemlate mongoTemplate;

    public String callDBAndBackend() {

        // some business logic
        UpdatedObject mongoDoc = mongoTemplate.updateFirst(updateObject);

        restTemplate.exchange(reqEntity, ResponseObject.class);
        return "Success";
    }
}

@ExtendWith(MockitoExtension.class)
MyTestServiceTest {

    @Mock
    private RestTemplate restTemplate;

    @Mock
    private MongoTemplate mongoTemplate;


    @InjectMocks
    private MyTestService myTestService;

    @Test
    public void testCallDBAndBackend() {

        when(restTemplate.exchange(reqEntity, ResponseObject.class)).thenReturn("Success"); // In this line getting Null pointer. Cant able to inject restTemplate
        when(mongoTemplate.updateFirst(updateObject)).thenReturn("Success"); // In //this line getting Null pointer. Cant able to inject mongoTemplate

    myTestService.callDBAndBackend();

    }
}

pom.xml

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
    </parent>

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
    <!--    <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>  -->
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>
<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-undertow</artifactId>
        </dependency>

编译此代码时，我将 RestTemplate 和 MongoTemplate 对象设为 null，这会导致 NPL。如果我从 IDE 运行相同的代码，它可以正常工作并获得有效的 RestTemplate 和 MongoTemplate 模拟对象。

Answer 1

您可以对目标类MyTestService 使用InjectMocks 注释来注入模拟对象。

您的解决方案应该为您提供 NLP，因为您没有将模拟对象提供给 MyTestService

即

@ExtendWith(MockitoExtension.class)
MyTestServiceTest{

@InjectMocks
private MyTestService service;

@Mock
private RestTemplate restTemplate;

@Mock
private MongoTemplate mongoTemplate;

@Test
public void testCallDBAndBackend() {
    // Arrange
    when(restTemplate.exchange(reqEntity,ResponseObject.class))
    .thenReturn("Success");
    when(mongoTemplate.updateFirst(updateObject)).thenReturn("Success");

     // Act
     String actual = service.callDBAndBackend();

     // Assert
     ...
    }
}