### Question:
NotificationData { public boolean isSingleMessageNotification() { return activeNotifications.size() == 1; } NotificationData(Account account); AddNotificationResult addNotificationContent(NotificationContent content); boolean containsStarredMessages(); boolean hasSummaryOverflowMessages(); int getSummaryOverflowMessagesCount(); int getNewMessagesCount(); boolean isSingleMessageNotification(); NotificationHolder getHolderForLatestNotification(); List<NotificationContent> getContentForSummaryNotification(); int[] getActiveNotificationIds(); RemoveNotificationResult removeNotificationForMessage(MessageReference messageReference); Account getAccount(); int getUnreadMessageCount(); void setUnreadMessageCount(int unreadMessageCount); ArrayList<MessageReference> getAllMessageReferences();  }### Answer:
@Test public void testIsSingleMessageNotification() throws Exception { assertFalse(notificationData.isSingleMessageNotification()); notificationData.addNotificationContent(createNotificationContent("1")); assertTrue(notificationData.isSingleMessageNotification()); notificationData.addNotificationContent(createNotificationContent("2")); assertFalse(notificationData.isSingleMessageNotification()); }