### Question:
ToDo { public String getId() { return id; } ToDo(); String getId(); void setId(String id); boolean isCompleted(); void setCompleted(boolean completed); String getTitle(); void setTitle(String title); int getOrder(); void setOrder(int order); @Override boolean equals(Object obj); @Override int hashCode();  }### Answer:
@Test public void testGetId() { ToDo td = new ToDo(); assertNull(td.getId()); td.setId("123abc"); assertEquals("123abc", td.getId()); }