怎样使用PowerMockito 测试静态方法

package mock.demo;
public class DemoStatic {
 public static String sayHello() {
  return "Hello";
 }
 
 public static String saySomething(String word) {
  return word;
 } 
 
 public static void sayAgain() {
  System.out.println(getMyWord());
 } 
 
 private static String getMyWord() {
  return "This is my word";
 }
}

@RunWith(PowerMockRunner.class)
@PrepareForTest({DemoStatic.class})
public class DemoStaticTest {
}

@PrepareForTest({DemoStatic.class})

  <dependency>
   <groupId>org.powermock</groupId>
   <artifactId>powermock-api-mockito</artifactId>
   <version>1.4.10</version>
  </dependency>
  <dependency>
   <groupId>org.powermock</groupId>
   <artifactId>powermock-module-junit4</artifactId>
   <version>1.4.10</version>
  </dependency>

 @Test
 public void testMockSayHello() {
  PowerMockito.spy(DemoStatic.class);
  PowerMockito.when(DemoStatic.sayHello()).thenReturn("my hello");
  
  System.out.println(DemoStatic.sayHello());  // my hello
 }

 @Test
 public void testSaySomething() throws Exception {
  PowerMockito.spy(DemoStatic.class);
  PowerMockito.when(DemoStatic.class, "saySomething", Mockito.anyString()).thenReturn("something to say!");
  
  System.out.println(DemoStatic.saySomething("say hello")); //something to say!
 }

 @Test
 public void testMockPrivate() throws Exception {
  PowerMockito.spy(DemoStatic.class);
  PowerMockito.when(DemoStatic.class, "getMyWord").thenReturn("Nothing to say");
  
  DemoStatic.sayAgain(); //Nothing to say
 }

Mocking Static Method：
// 1.类注解：@PrepareForTest(Static.class) //Static.class 是包含 static methods的类
方法内：
// 2.模拟静态类（使用PowerMockito.spy（class）模拟特定方法）
PowerMockito.mockStatic(Static.class);
// 3.拦截：设置期望值
Mockito.when(Static.firstStaticMethod(param)).thenReturn(value);

// 拦截的方法
<E, R> List<R> queryForList(Object var1, Class<E> var2, Function<E, R> var3);