ComposableRulesSpec.hs

{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE MultiParamTypeClasses #-}
module Warlock.ComposableRulesSpec (spec) where

import Data.Function ((&))
import Test.Hspec
import Warlock
import qualified Witch as W

-- Test the new composable field rule API
data Source = Source
  { srcBalance :: Int
  , srcName :: String
  , srcStatus :: String
  } deriving (Show, Eq)

data Dest = Dest
  { balance :: Int
  , displayName :: String
  , status :: String
  , region :: String
  } deriving (Show, Eq)

-- Demonstrate composable field rules
deriveAutomap
  ( ByName $
    defaultConfig
    `withRules`
    [ field 'balance & fromField 'srcBalance
    , field 'displayName & fromField 'srcName
    , field 'status & fromField 'srcStatus
    , field 'region & withDefault [| "US" |]
    ]
  )
  ''Source
  ''Dest

-- Test combining modifiers
data ComplexSource = ComplexSource
  { oldBalance :: Int
  , oldName :: String
  } deriving (Show, Eq)

data ComplexDest = ComplexDest
  { newBalance :: Int
  , newName :: String
  } deriving (Show, Eq)

deriveAutomap
  ( ByName $
    defaultConfig
    `withRules`
    [ field 'newBalance & fromField 'oldBalance & withDefault [| 0 |]
    , field 'newName & fromField 'oldName & withDefault [| "Unknown" |]
    ]
  )
  ''ComplexSource
  ''ComplexDest

spec :: Spec
spec = do
  describe "Composable Field Rules" $ do
    describe "Basic composition" $ do
      it "allows chaining 'from' modifier" $ do
        let src = Source 100 "Alice" "active"
            dst = W.from src :: Dest
        dst `shouldBe` Dest 100 "Alice" "active" "US"

      it "supports withDefault modifier" $ do
        let src = Source 50 "Bob" "inactive"
            dst = W.from src :: Dest
        region dst `shouldBe` "US"

    describe "Combined modifiers" $ do
      it "allows chaining from and withDefault" $ do
        let src = ComplexSource 200 "Charlie"
            dst = W.from src :: ComplexDest
        dst `shouldBe` ComplexDest 200 "Charlie"

      it "uses default when combining modifiers" $ do
        let src = ComplexSource 0 ""
            dst = W.from src :: ComplexDest
        newBalance dst `shouldBe` 0
        newName dst `shouldBe` ""

    describe "Mixing composable and pre-composed styles" $ do
      it "both styles work together" $ do
        let src = Source 300 "David" "pending"
            dst = W.from src :: Dest
        balance dst `shouldBe` 300
        displayName dst `shouldBe` "David"
        status dst `shouldBe` "pending"
        region dst `shouldBe` "US"