@hackage / quickcheck-classes

QuickCheck common typeclasses

Latest0.6.5.0

About

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  • Last updated , by andrewthad
  • License BSD-3-Clause
  • Categories Testing

  • Maintained by: andrew.thaddeus@gmail.com

  • Lottery factor: 0

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Installation

Package Flags

Use the -f option with cabal commands to enable flags

    aeson (on by default)

    You can disable the use of the aeson package using `-f-aeson`.

    This may be useful for accelerating builds in sandboxes for expert users.

    semigroupoids (on by default)

    You can disable the use of the semigroupoids package using `-f-semigroupoids`.

    This may be useful for accelerating builds in sandboxes for expert users.

    semirings (on by default)

    You can disable the use of the semirings package using `-f-semirings`.

    This may be useful for accelerating builds in sandboxes for expert users.

    vector (on by default)

    You can disable the use of the vector package using `-f-vector`.

    This may be useful for accelerating builds in sandboxes for expert users.

    unary-laws (on by default)

    Include infrastructure for testing class laws of unary type constructors. It is required that this flag match the value that the `unary-laws` flag was given when building `quickcheck-classes-base`.

    binary-laws (on by default)

    Include infrastructure for testing class laws of binary type constructors. It is required that this flag match the value that the `unary-laws` flag was given when building `quickcheck-classes-base`. Disabling `unary-laws` while keeping `binary-laws` enabled is an unsupported configuration.

Readme

quickcheck-classes

This library provides sets of properties that should hold for common typeclasses, along with three (3) simple functions that you can use to test them.

lawsCheck:

A convenience function for testing properties in GHCi. For example, at GHCi:

>>> lawsCheck (monoidLaws (Proxy :: Proxy Ordering))
Monoid: Associative +++ OK, passed 100 tests.
Monoid: Left Identity +++ OK, passed 100 tests.
Monoid: Right Identity +++ OK, passed 100 tests.

Assuming that the Arbitrary instance for Ordering is good, we now have confidence that the Monoid instance for Ordering satisfies the monoid laws.

lawsCheckMany:

A convenience function for checking multiple typeclass instances of multiple types. Consider the following Haskell source file:

import Data.Proxy (Proxy(..))
import Data.Map (Map)
import Data.Set (Set)

-- A 'Proxy' for 'Set' 'Int'. 
setInt :: Proxy (Set Int)
setInt = Proxy

-- A 'Proxy' for 'Map' 'Int' 'Int'.
mapInt :: Proxy (Map Int Int)
mapInt = Proxy

myLaws :: Proxy a -> [Laws]
myLaws p = [eqLaws p, monoidLaws p]

namedTests :: [(String, [Laws])]
namedTests =
  [ ("Set Int", myLaws setInt)
  , ("Map Int Int", myLaws mapInt)
  ]

Now, in GHCi:

>>> lawsCheckMany namedTests

Testing properties for common typeclasses
-------------
-- Set Int --
-------------

Eq: Transitive +++ OK, passed 100 tests.
Eq: Symmetric +++ OK, passed 100 tests.
Eq: Reflexive +++ OK, passed 100 tests.
Monoid: Associative +++ OK, passed 100 tests.
Monoid: Left Identity +++ OK, passed 100 tests.
Monoid: Right Identity +++ OK, passed 100 tests.
Monoid: Concatenation +++ OK, passed 100 tests.

-----------------
-- Map Int Int --
-----------------

Eq: Transitive +++ OK, passed 100 tests.
Eq: Symmetric +++ OK, passed 100 tests.
Eq: Reflexive +++ OK, passed 100 tests.
Monoid: Associative +++ OK, passed 100 tests.
Monoid: Left Identity +++ OK, passed 100 tests.
Monoid: Right Identity +++ OK, passed 100 tests.
Monoid: Concatenation +++ OK, passed 100 tests.
lawsCheckOne

A convenience function that allows one to check many typeclass instances of the same type.

For example, in GHCi:

>>> lawsCheckOne (Proxy :: Proxy Word) [jsonLaws, showReadLaws]
ToJSON/FromJSON: Encoding Equals Value +++ OK, passed 100 tests.
ToJSON/FromJSON: Partial Isomorphism +++ OK, passed 100 tests.
Show/Read: Partial Isomorphism +++ OK, passed 100 tests.