JUnit - Tutorial

A unit test is a piece of code written by a developer that tests a specific functionality in the code which is tested. Unit tests can ensure that functionality is working and can be used to validate that this functionality still works after code changes.

Unit testing uses also mocking of objects. To learn more about mock frameworks please see EasyMock Tutorial

1.2. Unit Testing with JUnit

JUnit 4.x is a test framework which uses annotation to identify the methods which contain tests. JUnit assumes that all test methods can be performed in an arbitrary order. Therefore tests should not depend other tests. To write a test with JUnit

Annotate a method with @org.JUnit.Test
Use a method provides by JUnit to check the expected result of the code execution versus the actual result

You use a tool like Eclipse or the class "org.junit.runner.JUnitCore" to run the test.

1.3. Installation of JUnit

Download JUnit4.x.jar from the JUnit website . The download contains a "junit-4.*.jar" which is the JUnit library. To make JUnit available in your Java project you have to add the the JUnit library file to your Java classpath. See Eclipse IDE Tutorial to learn how to do this in Eclipse.