PowerMockito无法正常工作，在我的代码中在这里

Question

 @RunWith(PowerMockRunner.class)
 @PrepareForTest(Topic_Service.class)
 class Topic_Service_test
 {
    private Topic_Service topic_service =  PowerMockito.spy(new Topic_Service());

    @Test
    void testing_test() throws Exception
    {
       PowerMockito.doReturn("hello").when(topic_service, "test_help");
       String s = topic_service.testing();
       Assertions.assertEquals("hello testing",s);
    }
 }


 @Service
 public class Topic_Service
 {
   public static String test_help()
   {
     return "test_help";
   }

   public String testing()
   {
     return test_help() + " " + "testing";
   }
 }

POM.XML Dependencies

        <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.mockito/mockito-core -->
    <dependency>
        <groupId>org.mockito</groupId>
        <artifactId>mockito-core</artifactId>
        <version> 2.8.47</version>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>org.powermock</groupId>
        <artifactId>powermock-module-junit4</artifactId>
        <version>1.7.0</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.powermock</groupId>
        <artifactId>powermock-api-mockito2</artifactId>
        <version>1.7.0</version>
        <scope>test</scope>
    </dependency>

错误：-

警告：发生了非法的反射访问操作警告：org.powermock.reflect.internal.WhiteboxImpl（文件：/home/an.kumar1/.m2/repository/org/powermock/powermock-reflect/1.7.0/powermock-reflect-1.7.0的非法反射访问。 jar）方法java.lang.Object.finalize（）警告：请考虑将此报告给org.powermock.reflect.internal.WhiteboxImpl的维护者警告：使用--illegal-access = warn启用有关进一步非法反射访问操作的警告警告：所有非法访问操作将在以后的版本中被拒绝

org.opentest4j.AssertionFailedError：预期：您好测试实际的：null

有人可以帮忙吗？在此先感谢

Answer 1

在类批注@RunWith（PowerMockRunner。class）上使用它

@RunWith (PowerMockRunner.class)
class Topic_Service_test
 {
    private Topic_Service topic_service =  PowerMockito.spy(new Topic_Service());

    @Test
    void testing_test() throws Exception
    {
       PowerMockito.doReturn("hello").when(topic_service, "test_help");
       String s = topic_service.testing();
       Assertions.assertEquals("hello testing",s);
    }
 }