### Question:
CommandProgressImpl extends ProgressStatusImpl implements CommandProgress, Serializable { @Override public synchronized ProgressStatusMirroringImpl createMirroringChild(int allocatedSteps) { allocateStapsForChildProcess(allocatedSteps); String childId = (id == null ? "" : id) + "." + (children.size() + 1); ProgressStatusMirroringImpl result = new ProgressStatusMirroringImpl(null, this, childId); children.add(new ChildProgressStatus(allocatedSteps, result)); fireEvent(new ProgressStatusEventCreateChild(id, null, result.getId(), allocatedSteps, -1)); return result; } CommandProgressImpl(String name, String id); @Override void setEventBroker(AdminCommandEventBroker eventBroker); @Override synchronized ProgressStatusMirroringImpl createMirroringChild(int allocatedSteps); @Override Date getEndTime(); @Override Date getStartTime(); @Override String getId(); @Override String getName(); @Override String getLastMessage(); @Override void complete(); @Override void complete(String message); @Override boolean isSpinnerActive();  }### Answer:
@Test public void testCreateMirroringChild() { CommandProgressImpl cp = new CommandProgressImpl("first", "a"); cp.setTotalStepCount(2); ProgressStatusMirroringImpl ch1 = cp.createMirroringChild(1); assertNotNull(ch1); ProgressStatus ch2 = cp.createChild(1); assertNotNull(ch1); assertTrue(ch2 instanceof ProgressStatusImpl); }