In Netbeans 6.7 you can invoke, and especially debug unit tests in the following way:
1. From test results:
- Invoke context menu on a given test and select 'Debug'
2. From project
- Select test file and choose "Debug->Debug Test File" from main menu or press Ctrl_Shift_F6 (on Mac Cmd_Shift_F6)
The way on how test are executed is changed right after 6.5, you may get more insight from http://www.netbeans.org/issues/show_bug.cgi?id=119922
Please also check http://www.netbeans.org/issues/show_bug.cgi?id=158812, to track the recent changes.
Thanks to Alexei Mokeev for providing this information - I was shortly before filing a P1 bug :-). In my opinion the Netbeans 6.5 way was more intuitive.