Documentation

This class is meant to be derived Generically for the construction of TestSuites only. Which is done in basically two settings:

1. For enumeration types matching the ConformanceTests in a module one-to-one.
2. For sums of other SmallKey types for the composition of TestSuites.

In essence, deriving an instance of this class is a declaration that the type has a small finite number of values and that allKeys (getAllKeys) constains them all. "Small" here is a performance requirement, meaning that it is feasible to drive an exhaustive construction from its values.

Laws:

Any inhabitant of a SmallKey type must have a finite index in allKeys, which must contain no duplicates. That is, whenever we have an Eq instance for the type, the following should hold:

elem x allKeys ==> length (filter (== x) allKeys) == 1