Unit Testing in Java

The exercises in this project are designed to help you understand unit testing in Java.

Getting Started

To get started, open the project file located in java-unit-testing/pom.xml in IntelliJ.

Project Overview

This project contains two application classes:

• Calculator - A simple calculator class that contains methods for adding, subtracting, multiplying, and dividing two numbers.
• Account - A simple account class that contains methods for depositing and withdrawing money from an account.

This project also contains two test classes for testing each of the application classes:

• CalculatorTests - Contains tests for the Calculator class.
• AccountTests - Contains tests for the Account class.

Exercise

To complete this exercise, you will need to complete the test classes to contain appropriate tests for the Calculator and Account classes.

To write these tests, make sure you read the comments in the application classes to understand what each method is supposed to do. Then, write tests that verify that the methods work as expected.

CalculatorTests

The CalculatorTests class contains tests for the Calculator class. You will need to write a test for all of the operations.

The Calculator class contains only methods, and no state. This means that your test should generally only need to call the method and verify that the return value is correct.

You should specifically take care when writing the Divide test to ensure that you are testing for the correct behavior when dividing by zero (an exception should be thrown).

AccountTests

The AccountTests class contains tests for the Account class. You will need to write tests for the deposit and withdraw methods.

The Account class contains state (the balance of the account), so you will need to write tests that call the methods, and then verify the return value if there is one, and the balance of the account after the method is called.

This class has a particular problem with the withdraw method that your test should catch. When your test failes on this condition, you should fix the Account class to handle this case correctly.

Running the Tests

As always, final verification of your code should be done by running the unit tests. This project is a bit different from the previous projects in that you are creating the tests yourself. This means that the only real way to verify that your tests are correct is to consider the expected behavior of the methods you are testing and make sure that your tests verify that behavior.