调用真实方法后，PowerMockito 模拟被清除

Question

我在使用 PowerMockito 静态方法模拟时遇到了一种奇怪的行为。

注意：2020-08-27是执行测试时的真实系统时间。

如您所见，在上面的代码示例中，我模拟了LocalDate.now() 方法的所有实现以及LocalDateTime.now() 方法的所有实现。同时我想要LocalDateTime.of(LocalDate, LocalTime)方法的真正实现。

在我调用 LocalDateTime.of(LocalDate, LocalTime) 方法之前，所有模拟都正常工作。

当我在调用LocalDateTime.of(LocalDate, LocalTime) 之后调用LocalDateTime.now() 时，我第一次得到真正的系统时间而不是模拟值。但是，如果我再次LocalDateTime.now()，那么我将再次获得嘲笑时间。

上面附有模拟结果的调试屏幕截图。这是我正在使用的代码。

@RunWith(PowerMockRunner.class)
@PowerMockIgnore({"com.sun.org.apache.xerces.*", "javax.xml.*", "org.xml.*", "org.w3c.dom.*"})
// This is needed due to a compatibility issue of Power Mock with JDK 9 (https://github.com/powermock/powermock/issues/864#issuecomment-447001997)
public class MainTest {

    @Test
    public void test() {
        LocalDate now = LocalDate.now();

        String dateString = "2020-08-24T09:00:00Z";
        Instant instant = Instant.parse(dateString);
        LocalDate localDate = LocalDate.ofInstant(instant, ZoneId.of("UTC"));
        LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.of("UTC"));

        PowerMockito.mockStatic(LocalDate.class);
        PowerMockito.when(LocalDate.now()).thenReturn(localDate);
        PowerMockito.when(LocalDate.now(Mockito.any(ZoneId.class))).thenReturn(localDate);
        PowerMockito.when(LocalDate.now(Mockito.any(Clock.class))).thenReturn(localDate);

        PowerMockito.mockStatic(LocalDateTime.class);
        PowerMockito.when(LocalDateTime.of(Mockito.any(LocalDate.class), Mockito.any(LocalTime.class))).thenCallRealMethod();
        PowerMockito.when(LocalDateTime.now()).thenReturn(localDateTime);
        PowerMockito.when(LocalDateTime.now(Mockito.any(ZoneId.class))).thenReturn(localDateTime);
        PowerMockito.when(LocalDateTime.now(Mockito.any(Clock.class))).thenReturn(localDateTime);

        LocalDate now1 = LocalDate.now();
        LocalDateTime of = LocalDateTime.of(localDate, LocalTime.of(10, 30));
        LocalDate now2 = LocalDate.now();
        LocalDate now3 = LocalDate.now();
        System.out.println("");
    }
}

我已经花了几个小时寻找根本原因，但不幸的是还没有运气。谁能告诉我这里出了什么问题？

Answer 1

这看起来像是 PowerMockito.mockStatic 本身的错误。我也在https://github.com/powermock/powermock/issues/1066 上发布了同样的内容。但我还没有得到任何回应。无论如何，我能够使用PowerMockito.stub 方法为我的用例找到解决方案。以下代码按预期工作，没有任何问题。

@RunWith(PowerMockRunner.class)
@PowerMockIgnore({"com.sun.org.apache.xerces.*", "javax.xml.*", "org.xml.*", "org.w3c.dom.*"})
// This is needed due to a compatibility issue of Power Mock with JDK 9 (https://github.com/powermock/powermock/issues/864#issuecomment-447001997)
public class MainTest {

    @Test
    public void test() {
        LocalDate now = LocalDate.now();

        String dateString = "2020-08-24T09:00:00Z";
        Instant instant = Instant.parse(dateString);
        LocalDate localDate = LocalDate.ofInstant(instant, ZoneId.of("UTC"));
        LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.of("UTC"));

        PowerMockito.stub(PowerMockito.method(LocalDate.class, "now")).toReturn(localDate);
        PowerMockito.stub(PowerMockito.method(LocalDate.class, "now", ZoneId.class)).toReturn(localDate);
        PowerMockito.stub(PowerMockito.method(LocalDate.class, "now", Clock.class)).toReturn(localDate);

        PowerMockito.stub(PowerMockito.method(LocalDateTime.class, "now")).toReturn(localDateTime);
        PowerMockito.stub(PowerMockito.method(LocalDateTime.class, "now", ZoneId.class)).toReturn(localDateTime);
        PowerMockito.stub(PowerMockito.method(LocalDateTime.class, "now", Clock.class)).toReturn(localDateTime);

        LocalDate now1 = LocalDate.now();
        LocalDateTime of = LocalDateTime.of(localDate, LocalTime.of(10, 30));
        LocalDate now2 = LocalDate.now();
        LocalDate now3 = LocalDate.now();
        System.out.println("");
    }
}

两种方法的区别在于PowerMockito.mockStatic 我模拟整个类，然后用PowerMockito.when 定义每个方法的行为。未使用PowerMockito.when 定义的方法如果被调用，将返回 null 或不执行任何操作。但是对于PowerMockito.stub，我不会嘲笑整个班级。我仅使用PowerMockito.stub 为一组选定的方法定义模拟行为，如果调用其他方法，则将调用真实方法。