Chooser

A simple one-method trait to allow you to pick values within a range.

Quite often in test code, you need to pick a specific value for a given type within a range. This typeclass represents that notion. You can think of it as the generalization of functions in Randomizer such as chooseChar, chooseFloat or choosePosInt. It is appropriate to use this typeclass when you are writing a function that needs this notion of "choosing", and works for multiple types.

In principle, this typeclass makes sense for any ordered type with a finite number of values. However, it is a bit different from scala.math.Ordering in that it is specifically built around ScalaTest's Randomizer. This is not attempting to choose truly random values; it is choosing pseudo-random values via Randomizer, so that the results can be replayed for debugging if necessary. This is very important: all "randomness" in making the choice should come from the provided Randomizer.

This typeclass is used as the basis for CommonGenerators.between, so that you can use that function with your own types by creating an implicit instance of Chooser. (Note that such types will also requires instances of Generator and Ordering.)