PowerMockito mock gets cleared after calling real method

I'm experiencing a weird behaviour with PowerMockito static method mocking.

Note: 2020-08-27 is the real system time at the time of executing the test.

In the above code example as you can see I have mocked all the implementations of LocalDate.now() method and all the implementations of LocalDateTime.now() method. And I want the real implementation of LocalDateTime.of(LocalDate, LocalTime) method at the same time.

All the mocks are working correctly until I call the LocalDateTime.of(LocalDate, LocalTime) method.

When I call the LocalDateTime.now() after calling LocalDateTime.of(LocalDate, LocalTime) I get the real system time not the mock value for the 1st time. But if I LocalDateTime.now() again then I again get the mocked time.

A debug screenshot is attached above with the mock results. This is the code I'm using.

@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("");
}
}

I have spent several hours looking out for the root cause but unfortunately no luck yet. Can someone please tell me what is wrong here?

This looks like a bug with PowerMockito.mockStatic itself. I posted the same at https://github.com/powermock/powermock/issues/1066 also. But I didn't get any response yet. Anyway, I was able to find a solution for my use case with PowerMockito.stub method. The following code piece works as expected without any issue.

@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("");
}
}

The difference between 2 approaches are with PowerMockito.mockStatic I mock the whole class and then define the behaviour of each method with PowerMockito.when. The methods which haven't been defined with PowerMockito.when will return null or do nothing if invoked. But with PowerMockito.stub I don't mock the whole class. I define the mocked behaviour only for a selected set of methods with PowerMockito.stub and other methods will call the real methods if invoked.