Unit Testing for Magik has it's on page Magik Unit Testing (MUnit) under Technical->Magik Language.
Event Recording (by FCSI)
This module allows you to record mouse and keyboard events in the Smallworld application. This allows you to easily create repeatable functional tests of your GUIs and wizards that require user interactions.
Magik Development Tools (MDT) (by MDT)
MDT® is an IDE for development of Smallworld applications. It’s the fastest and smartest way to deliver your Smallworld solutions. It is based on Eclipse