final LocalFileSink.SpaceChecker spaceChecker = mock(LocalFileSink.SpaceChecker.class);
when(spaceChecker.hasEnoughSpace()).thenReturn(false);
Sink sink = mapper.readValue(localFileSinkSpec, new TypeReference<Sink>(){});
sink.open();
Thread.sleep(1000); // wait until thread starts
assertNull(sink.recvNotice());