Workshop 17: The Absolute Beginner’s Guide to JUnit in the Classroom

Download the JUnit.jar from the JUnit home and place it in a location that makes sense for your computer configuration. Capture the path for that location and use it below.

Windows

set JUNIT_HOME=c:\Users\Name\Development
set CLASSPATH=%JUNIT_HOME%\junit.jar

Unix (Bash shell)

export JUNIT_HOME=/Users/Name/Development
export CLASSPATH=$JUNIT_HOME/junit.jar:$CLASSPATH

With the definitions from above, you can now compile your source files and your test classes.

% javac Student.java StudentTest.java

Use the JUnit test runner to run your test cases. The output will show information about which test cases passed and which failed.

For more information on how to run the command line test runner, check http://junit.sourceforge.net/doc/faq/faq.htm#running_1. There is also information on that page about how to run JUnit from Ant.

% java org.junit.runner.JUnitCore StudentTest

(a) Click Settings > PATH/CLASSPATH > Workspace. Then click (b) CLASSPATHs tab followed by the New button. Click New and find the desired junit.jar using the open file dialogue box. Once the file is selected, click OK, followed by (c) Apply on the outermost window.

To run your test cases, create a test suite and simply run your test case file as a standalone main program. The code on the right shows the static void main that creates a testing suite and adds and instance of the StudentTest class. Running StudentTest.class as a standalone project, causes the StudentTest to be run.

import junit.framework.*;

public class StudentTest extends TestCase
{
  public static void main (String[] args) {
    TestSuite suite = new TestSuite();
    suite.addTest(new StudentTest());
    junit.textui.TestRunner.run (suite);
  }

  public void testName()
  {
    Student student1 = new Student();
    student1.setName("Manuel");
    assertEquals("Manuel", student1.getName());
  }
}

The new JUnit plugin (version 1.1 of the plugin) includes support for JUnit 3.x and 4.x. Once you create a new project, the new NetBeans offers to download and install the JUnit plugin automatically. Go ahead and install it.

From the File menu, create a new Project. Select Java in the Categories panel followed by Java Class Library on the right panel. You can create the class and accept the default options. In this example, we use Student as the class name.

Next, lets create a test class for an existing class. First, create a new file, as in Step 2 above, but select JUnit on the Categories panel and Test for Existing Class on the right panel.

Enter the name of the class to test (or click browse and select it from a list of available classes). Next, indicate which JUnit version you will use. For this workshop, we are using JUnit 3.x. Now you are ready to use NetBeans to develop in Java and write JUnit test cases.

Create a new Eclipse project selecting File > New > Project. This will bring up a wizard that guides you through the creation of the project. (a) You first must select that you want a Java Project. Click Next.
(b) Then you specify the name of the project, and some of the other options. Use TestingEclipse for name and select the JavaSE-1.6 as JRE. Click Next.
(c) Finally, you just add the junit.jar to the project. Click the Libraries tab at the top, and click Add External JARs... on the right. Then find the folder named "plugins" that is in the Eclipse folder. That folder will have several versions of JUnit (3.8, 4.x, etc.). Find the JUnit.jar in the 4.x folder and add it to your project. Click Finish.

Next you can create a Java class following your normal use of Eclipse. We will assume you have created a Student.java class using the code linked above.
(a) Then select File > New > JUnit Test Case and another wizard will guide you through the steps.
(b) Enter the name StudentTest and at the bottom click Browse to select the Student class as the class to be tested. Click Finish.

The unit test created is shown on the right. Note that the code for the testSetName() simply has a fail() method call. This test case when run will always fail. Eclipse prepares the shell for JUnit test cases, the contents of the test case is up to you to fill in.

import junit.framework.*;

public class StudentTest extends TestCase 
{
  protected void setUp() throws Exception 
  {
    super.setUp();
  }

  public void testSetName()
  {
    fail("Not yet implemented");
  }
}

To run your test cases, (a) you select Run As > JUnit Test. This will attempt to run your project's test cases. The result of running your test cases is shown in Eclipse (b) indicating how many of your test cases passed or failed.