test objects design

From UML Pattern Language by Paul Evitts quoting Donald Schon passage from The Reflective Practicioner

A designer makes things. Sometimes he makes the final product; more often, he makes a
representation, plan, program, or image of an artifact to be constructed by others. He
works in particular situations, uses particular materials, and employs a distinctive
medium and language. Typically, his making process is complex. There are more
variables—kinds of possible moves, norms, and interrelationships of these—than can be
represented in a finite model. Because of this complexity, the designer’s moves tend,
happily or unhappily, to produce consequences other than those intended. When this
happens, the designer may take account of the unintended changes be has made in the
situation by forming new appreciations and understandings and by making new moves.
He shapes the situation, in accordance with his initial appreciation of it, the situation
“talks back,” and he responds to the situation’s back-talk.
In a good process of design, this conversation with the situation is reflective. In answer to
the situation’s back-talk, the designer reflects-in-action on the construction of the
problem, the strategies of action, or the model of the phenomena, which have been
implicit in his moves.