>System Info: 
  Product Version         = NetBeans IDE 6.0 M10 (build 200706281431)
  Operating System        = Windows 2003 version 5.2 running on x86
  Java; VM; Vendor        = 1.6.0_01; Java HotSpot(TM) Client VM 1.6.0_01-b06; Sun Microsystems Inc.
  Java Home               = C:\Program Files\Java\jdk1.6.0_01\jre

Generating a simple test case for a Netbeans Module Project class, with Tools->Create Junit Tests :-
1. Generate 3.x test case, IDE shows no error decorations for generated test class, but fails compilation

Compiling 1 source file to C:\temp\downloads\netbeans\work\Dialogs\JUnit3.2Test\build\test\unit\classes
C:\temp\downloads\netbeans\work\Dialogs\JUnit3.2Test\test\unit\src\test\junit3\test\JUnit32TestTest.java:10: package 
junit.framework does not exist
import junit.framework.TestCase;

2. Generate 4.x test case, IDE shows error decorations for generated test class,as Issue 106982.
Basically package org.junit can not be found. Also compilation fails.

Compiling 1 source file to C:\temp\downloads\netbeans\work\Dialogs\JUnit4.1Test\build\test\unit\classes
C:\temp\downloads\netbeans\work\Dialogs\JUnit4.1Test\test\unit\src\test\junit4\test\JUnit41TestTest.java:10: package 
org.junit does not exist
import org.junit.Test;


Copying junit-3.8.2.jar and junit-4.1.jar from java1/modules/ext to ide8/modules/ext. Allows both tests to be run. But 
error decorations are still shown for the 4.1 version though.