Prerequisite

• You must have installed jdk 6 (download it from Java SE downloads).

  Or else you can follow Installing Java from my article.

• Download Eclipse IDE zip archive from (e.g.: Helios version for Java EE) http://www.eclipse.org/ and unarchive it. This version of Eclipse (Helios) should already contain the junit4 plug-in.
• Download the latest release of junit – the jar file or zip file with jar and sources – from http://www.junit.org. Currently junit4.10 release is the latest.If you download the zip unpack it to a folder (e.g.: D:\Automation Workspace\lib – it will result junit4.10 subdirectory containing junit-4.10.jar, javadocs and others).

Setup the test environment

1. Open Eclipse and create a new Java Project.

Click File > New > Java Project > Enter "JseUnitTesting" as project name > Finish

2. You should already have a source directory called: src. Create another one called test.

Right Click on the project > New > Source Folder



Enter "test" as Folder Name > Finish

3. From the menu access Project(or simply Right Click on the project) > Properties > Libraries tab > Add External JARs >



Select the downloaded JAR(junit4.10) from the folder (e.g.: D:\Automation Workspace\lib) > Now we have the junit jar in our build path. Press OK button

4. In the Package Explorer tab the new added junit library is displayed under Referenced Libraries:

   
   
   We are now ready to start developing and running junits in Eclipse IDE.
   
   Note: If you don’t have Eclipse Helios version or other version which comes with junit 4 plugin, you should download the plugin separately and install it in Eclipse.

Create a Java class

package junitSrc;

public class MyClass {
	public int multiply(int x, int y) {
		return x / y;
	}
}

Create a JUnit test

Create a JUnit test in test namely MyClassTest

Right click on test folder > New > Other... > Java > JUnit > JUnitTestCase >

Next > Finish

Create a test with the following code looking in the figure

package junitTest;

import junitSrc.MyClass;
import org.junit.Test;
import static org.junit.Assert.assertEquals;

public class MyClassTest {

	@Test
	public void testMultiply() {
		MyClass tester = new MyClass();
		assertEquals("Result::", 50, tester.multiply(10, 5));
	}
}

Run your test via Eclipse

Right click on your new test class and select Run-As > JUnit Test.

The result of the tests will be displayed in the JUnit View.

The test should be failing (indicated via a red bar).

This is because our multiplier class is currently not working correctly (it does a division instead of multiplication). Fix the bug and re-run test to get a green bar.

Create a Test Suite

If you have several tests you can combine them into a test suite. Running a test suite will execute all tests in that suite.

To create a test suite, select your test classes > right click on it > New > Other... > JUnit > JUnit Test Suite

Select "Next" and select the methods for which you want to create a test.

Change the code to the following to make your test suite run your test. If you develop another test later you can add it to @Suite.SuiteClasses.

package junitTest;

import org.junit.runner.RunWith;
import org.junit.runners.Suite;

@RunWith(Suite.class)
@Suite.SuiteClasses({ MyClassTest.class })
public class AllTests {} 

Run your test via code

You can also run your tests from via your own code. The class org.junit.runner.JUnitCore provides the method runClasses() which allows you to run one or several tests classes. As a return parameter you receive an object of the type org.junit.runner.Result. This object can be used to retrieve information about the tests.

In your "test" folder create a new class MyTestRunner with the following code. This class will execute your test class and write potential failures to the console.

package junitTest;

import org.junit.runner.JUnitCore;
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;

public class MyTestRunner {
  public static void main(String[] args) {
	Result result = JUnitCore.runClasses(MyClassTest.class);
	for (Failure failure : result.getFailures()) {
	  System.out.println(failure.toString());
	}
  }
} 

For more details please go through my post Getting started with Selenium RC (selenium 1) with JUnit 3 or JUnit 4 and more examples.