There are two major concerns relative to testing. The first is general testing of functionality of major applications (e.g., KWWidgets summary pages).
In the first situation, testing processes are well established (see the NAMIC Software Process description). The DART testing server and CTest testing client are already in place and used to test VTK, ITK amd Slicer.
Testing GUI's is harder. The general approach is to record user interaction sessions in a script, and then play back the script of events to drive the GUI at a later date (i.e., during a test). Then the state of the application, or its output, can be compared against the original run to determine whether the test passed or failed. Currently the KWWidgets provides partial scripting support. We are extending the toolkit to support scripting.