quickcheck-monoid-subclasses: Testing monoid subclass instances with QuickCheck

[ apache, library, testing ] [ Propose Tags ]

QuickCheck support for testing instances of type classes defined in the monoid-subclasses library.

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Dependencies base (>= && <4.20), containers (>= && <0.8), monoid-subclasses (>=1.2.3 && <1.3), pretty-show (>=1.10 && <1.11), QuickCheck (>=2.14.2 && <2.15), quickcheck-classes (>= && <0.7), quickcheck-instances (>=0.3.28 && <0.4), quickcheck-monoid-subclasses, semigroupoids (>=5.3.7 && <6.1) [details]
License Apache-2.0
Copyright 2022–2024 Jonathan Knowles
Author Jonathan Knowles
Maintainer mail@jonathanknowles.net
Category Testing
Bug tracker https://github.com/jonathanknowles/quickcheck-monoid-subclasses/issues
Source repo head: git clone https://github.com/jonathanknowles/quickcheck-monoid-subclasses
Uploaded by JonathanKnowles at 2024-04-11T06:40:27Z
Distributions LTSHaskell:, NixOS:, Stackage:
Downloads 608 total (59 in the last 30 days)
Rating 2.0 (votes: 1) [estimated by Bayesian average]
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Status Docs available [build log]
Last success reported on 2024-04-11 [all 1 reports]

Readme for quickcheck-monoid-subclasses-

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The quickcheck-monoid-subclasses library provides:


In general, usage is identical to that of the quickcheck-classes library. If you're already familiar with quickcheck-classes, then using this library should be straightforward.

Testing laws for a single type class

To test that the laws of a particular class hold for a particular type, use the lawsCheck function with the Laws definition for the class you wish to test.

🌠 Example

To test that the Monus laws hold for the Sum Natural type:

import Data.Monoid (Sum)
import Data.Proxy (Proxy (Proxy))
import Numeric.Natural (Natural)
import Test.QuickCheck.Classes (lawsCheck)
import Test.QuickCheck.Classes.Monoid.Monus (monusLaws)

lawsCheck (monusLaws (Proxy :: Proxy (Sum Natural)))

If all tests pass, you should see output similar to:

Monus: axiom1 +++ OK, passed 100 tests.
Monus: axiom2 +++ OK, passed 100 tests.
Monus: axiom3 +++ OK, passed 100 tests.
Monus: axiom4 +++ OK, passed 100 tests.
Monus: stripPrefixOverlap +++ OK, passed 100 tests.
Monus: stripSuffixOverlap +++ OK, passed 100 tests.

Testing laws for multiple type classes

To test that the laws of multiple classes hold for a particular type, use the lawsCheckOne function with the Laws definitions for the classes you wish to test.

🌠 Example

To test that the Sum Natural type satisfies the laws of Semigroup and its subclasses:

import Data.Monoid (Sum)
import Data.Proxy (Proxy (Proxy))
import Numeric.Natural (Natural)
import Test.QuickCheck.Classes
import Test.QuickCheck.Classes.Monoid.GCD
import Test.QuickCheck.Classes.Monoid.LCM
import Test.QuickCheck.Classes.Monoid.Monus
import Test.QuickCheck.Classes.Monoid.Null
import Test.QuickCheck.Classes.Semigroup.Cancellative
import Test.QuickCheck.Classes.Semigroup.Factorial

lawsCheckOne (Proxy :: Proxy (Sum Natural))
    [ cancellativeLaws
    , commutativeLaws
    , distributiveGCDMonoidLaws
    , distributiveLCMMonoidLaws
    , factorialLaws
    , factorialMonoidLaws
    , gcdMonoidLaws
    , lcmMonoidLaws
    , leftCancellativeLaws
    , leftDistributiveGCDMonoidLaws
    , leftGCDMonoidLaws
    , leftReductiveLaws
    , monoidLaws
    , monoidNullLaws
    , monusLaws
    , overlappingGCDMonoidLaws
    , positiveMonoidLaws
    , reductiveLaws
    , rightCancellativeLaws
    , rightDistributiveGCDMonoidLaws
    , rightGCDMonoidLaws
    , rightReductiveLaws
    , semigroupLaws
    , stableFactorialLaws

Subclasses and superclasses

Each of the Laws definitions provided by this library corresponds to exactly one type class, and includes just the laws for that class. Laws for subclasses and superclasses are not automatically included. Therefore, you'll need to explicitly test the laws of every single class you wish to cover.

Coverage checks

This library includes coverage checks to ensure that important cases are covered, and to reduce the probability of test passes that are false positives. These coverage checks are performed automatically.

To increase coverage of interesting and important cases, this library also checks that laws hold for combinations of generated arbitrary values.

🌠 Example

Suppose we are testing the following law:

isPrefixOf a b == isJust (stripPrefix a b)

This library will also test that the following derived laws hold:

isPrefixOf a (a <> a) == isJust (stripPrefix a (a <> a))
isPrefixOf a (a <> b) == isJust (stripPrefix a (a <> b))
isPrefixOf a (b <> a) == isJust (stripPrefix a (b <> a))