QuickCheck is a library for random testing of program properties.

The programmer provides a specification of the program, in the form of
properties which functions should satisfy, and QuickCheck then tests
that the properties hold in a large number of randomly generated
cases.

Specifications are expressed in Haskell, using combinators defined in
the QuickCheck library. QuickCheck provides combinators to define
properties, observe the distribution of test data, and define test
data generators.

Homepage:
https://hackage.haskell.org/package/QuickCheck
