Chapter 9, Problem 20E

Program Plan Intro

Program plan:

The variables used in the program are given below:

1. item: SalesItem - an instance of the SalesItem class, which represents a sales item being sold on a website or in a store.
2. comment1: Comment - an instance of the Comment class, which represents a comment left by a user about the sales item.
3. comment2: Comment - another instance of the Comment class, representing a second comment about the sales item.
4. comment3: Comment - a third instance of the Comment class, representing a third comment about the sales item.

The methods used in the program are as follows:

1. addComment(comment: Comment): void - a method of the SalesItem class that adds a new Comment object to the item's list of comments.
2. getComments(): List - a method of the SalesItem class that returns a list of all Comment objects that have been added to the item.
3. assertEquals(expected: int, actual: int): void - a method of the org.junit.Assert class that checks if two integer values are equal, and throws an assertion error if they are not.
4. assertTrue(condition: boolean): void - a method of the org.junit.Assert class that checks if a given boolean condition is true, and throws an assertion error if it is not.
5. testAddNullComment(): a unit test method that tests the behavior of the SalesItem class when attempting to add a null comment to an item. Expects an IllegalArgumentException to be thrown.

Program Description:

The given code is a unit test written in JUnit framework for the addComment() method of the SalesItem class. It creates a new SalesItem object with a name and description and then adds three comments to it using addComment() method. The test then checks that the comments were added successfully by verifying that the size of the SalesItem's comments list is 3 and that each of the three comments is contained in the list. This is an important test to ensure that comments can be successfully added to a SalesItem object, which is a critical feature of the class for user interaction and feedback.