@hackage quickcheck-classes0.6.2.1

QuickCheck common typeclasses

  • Installation

  • Dependencies (17)

  • Dependents (58)

    @hackage/prim-instances, @hackage/linnet-conduit, @cardano/cardano-data, @hackage/poly, @cardano/marlowe-object, @hackage/disjoint-containers, Show all…

    • Package 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.

      binary-laws
       (on by default)

      Include infrastructure for testing class laws of binary type constructors. Disabling `unary-laws` while keeping `binary-laws` enabled is an unsupported configuration.

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.