Drupal now has its own testing framework. Using the simpletest framework enabled us to write tests without trying to envision and build our own framework. However, once a number of tests had been created, it seemed better to gradually replace the SimpleTest framework because it's so very un-Drupalish. First I have rewritten its browser and now we (mostly cwgordon7, dmitrig01 and me) have totally removed it. The new framework came about because we wanted to use batch API and the best place for collecting the messages was a database table.