### Question:
AbstractContact implements IContact { public void setUnknown(boolean unknown) { this.unknown = unknown; }  boolean isUnknown(); void setUnknown(boolean unknown); boolean isNewbie(); void setNewbie(boolean newbie); IMessage getLastMessage(); void setLastMessage(IMessage lastMessage); int getUnread(); void setUnread(int unread); void clearUnRead(); void increaceUnRead(); int compareTo(AbstractContact that);  }### Answer:
@Test public void testSetUnknown() { contact.setUnknown(true); assertEquals(true, contact.isUnknown()); }