Test.QuickCheck.Arbitrary.ADT

{-# LANGUAGE DeriveGeneric #-}

import Data.Proxy
import GHC.Generics
import Test.QuickCheck
import Test.QuickCheck.Arbitrary.ADT

-- Sum Type, multiple constructors with parameters
data Fruit
  = Apple Int
  | Orange String Int
  | PassionFruit Int String Int
  deriving (Generic, Show)

-- Product Type, single constructor
data Person =
  Person
    { name :: String
    , age  :: Int
    } deriving (Generic, Show)

instance Arbitrary Fruit where
  arbitrary = genericArbitrary

instance ToADTArbitrary Fruit

instance Arbitrary Person where
  arbitrary = genericArbitrary

instance ToADTArbitrary Person

λ> generate (toADTArbitrarySingleton (Proxy :: Proxy Fruit))
ADTArbitrarySingleton {
  adtasModuleName = "Ghci1"
, adtasTypeName = "Fruit"
, adtasCAP = ConstructorArbitraryPair {
    capConstructor = "Apple", capArbitrary = Apple 30}}

λ> generate (toADTArbitrary (Proxy :: Proxy Fruit))
ADTArbitrary {
  adtModuleName = "Ghci1"
, adtTypeName = "Fruit"
, adtCAPs = [
    ConstructorArbitraryPair {
        capConstructor = "Apple"
      , capArbitrary = Apple 17}
  , ConstructorArbitraryPair {
        capConstructor = "Orange"
      , capArbitrary = Orange "abcdef" 18}
  , ConstructorArbitraryPair {
        capConstructor = "PassionFruit"
      , capArbitrary = PassionFruit 16 "datadata" 6}]}

λ> generate (toADTArbitrarySingleton (Proxy :: Proxy Person))
ADTArbitrarySingleton {
  adtasModuleName = "Ghci1"
, adtasTypeName = "Person"
, adtasCAP = ConstructorArbitraryPair {capConstructor = "Person", capArbitrary = Person {name = "John Doe", age = 30}}}

λ> generate (toADTArbitrary (Proxy :: Proxy Person))
ADTArbitrary {
  adtModuleName = "Ghci1"
, adtTypeName = "Person"
, adtCAPs = [ConstructorArbitraryPair {capConstructor = "Person", capArbitrary = Person {name = "Jane Doe", age = 15}}]}