This library provides property based testing with support
for internal integrated shrinking: integrated in the sense
of Hedgehog, meaning that there is no need to write a
separate shrinker and generator; and internal in the sense
of Hypothesis, meaning that this works well even across
monadic bind. However, the actual techniques that power
falsify are quite different from both of these two
libraries.
Most users will probably want to use the integration with
tasty,
and use Test.Tasty.Falsify as their main entrypoint
into the library. The Test.Falsify.Interactive module
can be used to experiment with the library in ghci.
Changes
Revision history for falsify
0.3.0 – 2026-03-05
Introduce new Range constructor called between, which can be used for
better uniform selection of large bit-size Integral types.
[#81, reported by Andrea Vezzosi]
Support generating functions from empty types [#84, Sjoerd Visscher]
Add minimalValue function [#86, Sjoerd Visscher]
Fix overflow in Fun Int8 [#89, reported by Jake McArthur]
The primitive Range constructor is now based on WordN rather than
ProperFraction. Most users will not notice this difference, but the
signature of the primitive eval function has changed.
Relax package bounds and test with ghc 9.14.1
0.2.0 – 2023-11-08
Avoid use of Expr in at (#48)
Add oneof (#54; Simon Kohlmeyer)
Generalize Range, so that it can be used for types like Char (#51).
As a consequence, Gen.integral and Gen.enum are now deprecated, and
superseded by Gen.inRange.
Add GenDefault class and DerivingVia helpers to derive generators
(Eric Conlon; #61, #64).
0.1.1 – 2023-04-07
Better verbose mode for test failures
New predicates: split and pairwise.
Shrink towards the second half of the range in withOrigin
