从另一个类方法调用时无法正确模拟方法调用

MyClass firstClass = PowerMockito.spy(new MyClass());

AnotherClass secondClass;
secondClass = PowerMockito.mock(AnotherClass.class);
PowerMockito.when(secondClass.anotherFunction(Mockito.any()).thenReturn(1);

int myInt = firstClass.myFunction();

if (myInt == 1) {
    System.out.println("true");
}
MyClass firstClass = PowerMockito.spy(new MyCla