Unit testing was part of the overall introduction of extreme programming/agile development, which is just one of the major trends Smalltalk has brought to the world. Along with refactoring (which we all know can’t be done without static types, which is why it was invented in a dynamically typed language), IDEs, reflective OO APIs, GUI builders, pop-up menus and bitmapped GUIs in general. Smalltalk is the veritable Prometheus of OO, and its destiny seems not dissimilar.