### Question:
DefaultStageService implements StageService { @Override public void clear() { Preferences prefs = Preferences.userRoot().node(STAGE_PATH); try { prefs.removeNode(); prefs.flush(); } catch (BackingStoreException e) { LOG.error("Unable to clear stage status", e); } }  @Override void save(StageStatus status); @Override StageStatus getLatestStatus(); @Override void clear();  }### Answer:
@Test public void testClear() { StageStatus status = new StageStatus(10, 20, 100, 200); victim.save(status); victim.clear(); assertTrue(isBlank(Preferences.userRoot().node(DefaultStageService.STAGE_PATH) .get(DefaultStageService.STAGE_STATUS_KEY, ""))); }