Target is a library for testing Haskell functions based on properties encoded as refinement types.
The programmer specifies the expected behavior of a function with a refinement type, and Target then checks that the function satisfies the specification by enumerating valid inputs up to some size, calling the function, and validating the output. Target excels when the space of valid inputs is a sparse subset of all possible inputs, e.g. when dealing with dataypes with complex invariants like red-black trees.
Test.Target is the main entry point and should contain
everything you need to use Target with types from the
Test.Target.Targetable will also be useful if
you want to test functions that use other types.
For information on how to specify interesting properties with refinement types, we have a series of blog posts as well as an evolving tutorial. Target uses the same specification language as LiquidHaskell, so the examples should carry over.