Add checks for Enum

src/Test/QuickCheck/Laws.purs

@@ -5,7 +5,7 @@ module Test.QuickCheck.Laws
 
 import Prelude
 import Control.Monad.Eff.Console (log)
-import Data.Enum (class BoundedEnum)
+import Data.Enum (class Enum, class BoundedEnum)
 import Data.Monoid (class Monoid)
 import Test.QuickCheck (QC)
 import Test.QuickCheck.Arbitrary (class Arbitrary, class Coarbitrary)
@@ -21,6 +21,7 @@ derive newtype instance arbitraryA ∷ Arbitrary A
 derive newtype instance boundedA ∷ Bounded A
 derive newtype instance boundedEnumA :: BoundedEnum A
 derive newtype instance coarbitraryA ∷ Coarbitrary A
+derive newtype instance enumA ∷ Enum A
 derive newtype instance eqA ∷ Eq A
 derive newtype instance ordA ∷ Ord A
 derive newtype instance semigroupA ∷ Semigroup A
@@ -32,6 +33,7 @@ derive newtype instance arbitraryB ∷ Arbitrary B
 derive newtype instance boundedB ∷ Bounded B
 derive newtype instance boundedEnumB :: BoundedEnum B
 derive newtype instance coarbitraryB ∷ Coarbitrary B
+derive newtype instance enumB ∷ Enum B
 derive newtype instance eqB ∷ Eq B
 derive newtype instance ordB ∷ Ord B
 derive newtype instance semigroupB ∷ Semigroup B
@@ -43,6 +45,7 @@ derive newtype instance arbitraryC ∷ Arbitrary C
 derive newtype instance boundedC ∷ Bounded C
 derive newtype instance boundedEnumC :: BoundedEnum C
 derive newtype instance coarbitraryC ∷ Coarbitrary C
+derive newtype instance enumC ∷ Enum C
 derive newtype instance eqC ∷ Eq C
 derive newtype instance ordC ∷ Ord C
 derive newtype instance semigroupC ∷ Semigroup C
@@ -54,6 +57,7 @@ derive newtype instance arbitraryD ∷ Arbitrary D
 derive newtype instance boundedD ∷ Bounded D
 derive newtype instance boundedEnumD :: BoundedEnum D
 derive newtype instance coarbitraryD ∷ Coarbitrary D
+derive newtype instance enumD ∷ Enum D
 derive newtype instance eqD ∷ Eq D
 derive newtype instance ordD ∷ Ord D
 derive newtype instance semigroupD ∷ Semigroup D
@@ -65,6 +69,7 @@ derive newtype instance arbitraryE ∷ Arbitrary E
 derive newtype instance boundedE ∷ Bounded E
 derive newtype instance boundedEnumE :: BoundedEnum E
 derive newtype instance coarbitraryE ∷ Coarbitrary E
+derive newtype instance enumE ∷ Enum E
 derive newtype instance eqE ∷ Eq E
 derive newtype instance ordE ∷ Ord E
 derive newtype instance semigroupE ∷ Semigroup E

src/Test/QuickCheck/Laws/Data.purs

@@ -3,6 +3,7 @@ module Test.QuickCheck.Laws.Data (module Exports) where
 import Test.QuickCheck.Laws.Data.BooleanAlgebra (checkBooleanAlgebra) as Exports
 import Test.QuickCheck.Laws.Data.Bounded (checkBounded) as Exports
 import Test.QuickCheck.Laws.Data.CommutativeRing (checkCommutativeRing) as Exports
+import Test.QuickCheck.Laws.Data.Enum (checkEnum) as Exports
 import Test.QuickCheck.Laws.Data.Eq (checkEq) as Exports
 import Test.QuickCheck.Laws.Data.BoundedEnum (checkBoundedEnum) as Exports
 import Test.QuickCheck.Laws.Data.EuclideanRing (checkEuclideanRing) as Exports

src/Test/QuickCheck/Laws/Data/BoundedEnum.purs

@@ -9,6 +9,7 @@ import Data.Maybe (Maybe(Just))
 import Data.Newtype (unwrap)
 import Test.QuickCheck (QC, quickCheck')
 import Test.QuickCheck.Arbitrary (class Arbitrary)
+import Test.QuickCheck.Laws.Data.Enum (checkEnum)
 import Type.Proxy (Proxy)
 
 
@@ -26,7 +27,9 @@ checkBoundedEnum
   . (Arbitrary a, BoundedEnum a, Ord a)
   ⇒ Proxy a
   → QC eff Unit
-checkBoundedEnum _ = do
+checkBoundedEnum p = do
+
+  checkEnum p
 
   log "Checking 'succ' law for BoundedEnum"
   quickCheck' 1 succLaw

src/Test/QuickCheck/Laws/Data/Enum.purs

@@ -0,0 +1,43 @@
+
+module Test.QuickCheck.Laws.Data.Enum where
+
+import Prelude
+import Control.Monad.Eff.Console (log)
+import Data.Enum (pred, succ, class Enum)
+import Data.Maybe (Maybe(Nothing))
+import Test.QuickCheck (QC, quickCheck')
+import Test.QuickCheck.Arbitrary (class Arbitrary)
+import Type.Proxy (Proxy)
+
+checkEnum
+  ∷ ∀ eff a
+  . (Arbitrary a, Enum a, Ord a)
+  ⇒ Proxy a
+  → QC eff Unit
+checkEnum _ = do
+
+  log "Checking 'GT ordering' law for Enum"
+  quickCheck' 1000 gtordering
+
+  log "Checking 'LT ordering' law for Enum"
+  quickCheck' 1000 ltordering
+
+  log "Checking 'predsuccpred' law for BoundedEnum"
+  quickCheck' 1000 predsuccpredLaw
+
+  log "Checking 'succpredsucc' law for BoundedEnum"
+  quickCheck' 1000 succpredsuccLaw
+
+  where
+    gtordering ∷ a → Boolean
+    gtordering a = succ a == Nothing || succ a > pred a
+
+    ltordering ∷ a → Boolean
+    ltordering a = succ a == Nothing || pred a < succ a
+
+    predsuccpredLaw :: a -> Boolean
+    predsuccpredLaw a = succ a == Nothing || (pred a >>= succ >>= pred) == pred a
+
+    succpredsuccLaw :: a -> Boolean
+    succpredsuccLaw a = succ a == Nothing || (succ a >>= pred >>= succ) == succ a
+