- Create a main class
 
 import junit.textui.TestRunner; 
  public class TestBootstrap
  { 
   public static void main(String[] args) 
  { 
   TestSuite testSuite=new TestSuite();
   testSuite.addTestSuite(TestClass.class); 
   TestRunner.run(testSuite); 
   } 
 }
 2.  Create an ant build file
 <project> 
   <target name="eclipse-test-runner"> 
    <java classname="TestBootstrap" classpath="bin:libs/junit.jar"> <java>  </target> 
 </project>
 3. Create a Builder in eclipse
  Open project properties: Right click project -> Propertie. Create new ant builder step after the Java Builder in eclipse: Builders -> new -> Ant Builder. Give your builder a nice name.  
 Main: Select the build file and the base directory  
 Targets: Select your ANT target for: “After Clean”, “Manual Build”, and “Auto Build” (most important)                Build Options: Check “Specify working set” and select all of your source folders.
And thats all, now every time you save a file, eclipse will run the ant target specified in your build file, which incidentally calls your TestBootstrap's main and invoked all the tests.