### Question:
FolderObject extends ContentContainerObject { public WorkObject addWork() { return addWork(null); } protected  FolderObject(PID pid, RepositoryObjectDriver driver,
            RepositoryObjectFactory repoObjFactory); @Override FolderObject validateType(); @Override ContentContainerObject addMember(ContentObject member); FolderObject addFolder(); FolderObject addFolder(Model model); WorkObject addWork(); WorkObject addWork(Model model);  }### Answer:
@Test public void addWorkTest() { WorkObject childObj = new WorkObject(childPid, driver, repoObjFactory); when(repoObjFactory.createWorkObject(any(Model.class))).thenReturn(childObj); WorkObject workObj = folder.addWork(); verify(repoObjFactory).createWorkObject(null); assertTrue("Incorrect type of child added", workObj instanceof WorkObject); assertEquals("Child did not have the expected pid", childPid, workObj.getPid()); }