hedgehog: Hedgehog will eat all your bugs.

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Warnings:

'ghc-options: -O2' is rarely needed. Check that it is giving a real benefit and not just imposing longer compile times on your users.

Hedgehog is a modern property-based testing system, in the spirit of QuickCheck. Hedgehog uses integrated shrinking, so shrinks obey the invariants of generated values by construction.

To get started quickly, see the examples: https://github.com/hedgehogqa/haskell-hedgehog/tree/master/hedgehog-example

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Properties

Versions	0.1, 0.2, 0.2.1, 0.2.2, 0.3, 0.4, 0.4.1, 0.5, 0.5.1, 0.5.2, 0.5.2, 0.5.3, 0.6, 0.6.1, 1.0, 1.0.1, 1.0.2, 1.0.3, 1.0.4, 1.0.5, 1.1, 1.1.1, 1.1.2, 1.2, 1.3, 1.4, 1.5
Change log	CHANGELOG.md
Dependencies	ansi-terminal (>=0.6 && <0.9), async (>=2.0 && <2.2), base (>=3 && <5), bytestring (>=0.10 && <0.11), concurrent-output (>=1.7 && <1.11), containers (>=0.4 && <0.6), directory (>=1.2 && <1.4), exceptions (>=0.7 && <0.9), lifted-async (>=0.7 && <0.10), mmorph (>=1.0 && <1.2), monad-control (>=1.0 && <1.1), mtl (>=2.1 && <2.3), pretty-show (>=1.6 && <1.7), primitive (>=0.6 && <0.7), random (>=1.1 && <1.2), resourcet (>=1.1 && <1.3), semigroups (>=0.16 && <0.19), stm (>=2.4 && <2.5), template-haskell (>=2.10 && <2.14), text (>=1.1 && <1.3), th-lift (>=0.7 && <0.8), time (>=1.4 && <1.9), transformers (>=0.4 && <0.6), transformers-base (>=0.4 && <0.5), unix (>=2.6 && <2.8), wl-pprint-annotated (>=0.0 && <0.2) [details]
License	BSD-3-Clause
Author	Jacob Stanley
Maintainer	Jacob Stanley <jacob@stanley.io>
Category	Testing
Home page	https://hedgehog.qa
Bug tracker	https://github.com/hedgehogqa/haskell-hedgehog/issues
Source repo	head: git clone git://github.com/hedgehogqa/haskell-hedgehog.git
Uploaded	by JacobStanley at 2018-02-05T05:13:08Z

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hedgehog-0.5.2.tar.gz [browse] (Cabal source package)
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JacobStanley, moodmosaic

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Readme for hedgehog-0.5.2

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hedgehog

Hedgehog will eat all your bugs.

Hedgehog is a modern property-based testing system, in the spirit of QuickCheck. Hedgehog uses integrated shrinking, so shrinks obey the invariants of generated values by construction.

Features

Integrated shrinking, shrinks obey invariants by construction.
Abstract state machine testing.
Generators allow monadic effects.
Range combinators for full control over the scope of generated numbers and collections.
Equality and roundtrip assertions show a diff instead of the two inequal values.
Template Haskell test runner which executes properties concurrently.

Example

The main module, Hedgehog, includes almost everything you need to get started writing property tests with Hedgehog.

It is designed to be used alongside Hedgehog.Gen and Hedgehog.Range which should be imported qualified. You also need to enable Template Haskell so the Hedgehog test runner can find your properties.

{-# LANGUAGE TemplateHaskell #-}

import           Hedgehog
import qualified Hedgehog.Gen as Gen
import qualified Hedgehog.Range as Range

Once you have your imports set up, you can write a simple property:

prop_reverse :: Property
prop_reverse =
  property $ do
    xs <- forAll $ Gen.list (Range.linear 0 100) Gen.alpha
    reverse (reverse xs) === xs

And add the Template Haskell splice which will discover your properties:

tests :: IO Bool
tests =
  checkParallel $$(discover)

If you prefer to avoid macros, you can specify the group of properties to run manually instead:

{-# LANGUAGE OverloadedStrings #-}

tests :: IO Bool
tests =
  checkParallel $ Group "Test.Example" [
      ("prop_reverse", prop_reverse)
    ]

You can then load the module in GHCi, and run it:

λ tests
━━━ Test.Example ━━━
  ✓ prop_reverse passed 100 tests.