I have found a problem in 6.0M9 and recent daily builds (such as 200705131800)
when running tests for a NetBeans platform application, built on the IDE itself. 

To reproduce is simple:

1.  Create a new suite project

2.  Add a new module to the suite from step #1

3.  Create a basic class in your module, such as:

     public class SimpleMath {
    
         public long add(int n1, int n2) {
              return n1 + n2;
         }
     }

4.  Right-click your new class and use Tools ->  Create JUnit tests

5.  Update your test with a working implementation, such as:

     public void testAdd() {
        SimpleMath instance = new SimpleMath();        
        long result = instance.add(5, 8);
        assertEquals(13L, result);
     }

6. Right-click on your module and choose "Run unit tests".

The error seems to vary based on whether I am using a daily build or M9, but it
 cannot either find the junit.framework.TestCase class or the assert methods.  I
verified that the JUnit library is shown under Unit Test Libraries of the
module, but it doesn't find these classes/methods anyway.

Repeating these steps in 6.0M8 or 5.5 works as expected -- I can compile and run
the unit test without errors.