// 私有方法测试，无参 
Method method = PowerMockito.method(TestService.class, "methodName");
method.invoke(testService);
// 私有方法测试，传参
Method method = PowerMockito.method(TestService.class, "methodName", Test1.class, Test2.class);
method.invoke(testService, test1, test2);

// 加注解
@PrepareForTest({XXXUtil.class})
XXXServiceTest {

    @Test
    public void test() {
        // 调用PowerMockito.mockStatic
        PowerMockito.mockStatic(XXXUtil.class);
        when(XXXUtil.staticMethodName())...
    }
}

// 彻底mock某方法(不执行内部语句，public/private都可)
MemberModifier.stub(MemberMatcher.method(TestService.class, "methodName")).toReturn(false);