UsingConfigSpec.hs

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE InstanceSigs #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE UndecidableInstances #-}

module Servant.Server.UsingConfigSpec where

import           Network.Wai
import           Test.Hspec (Spec, describe, it)
import           Test.Hspec.Wai

import           Servant
import           Servant.Server.Internal.Router
import           Servant.Server.Internal.RoutingApplication

-- * custom test combinator

data CustomCombinator

data FromCombinator = FromCombinator String

instance forall subApi (c :: [*]) . (HasServer subApi) =>
  HasServer (CustomCombinator :> subApi) where

  type ServerT (CustomCombinator :> subApi) m =
    FromCombinator -> ServerT subApi m
  type HasCfg (CustomCombinator :> subApi) c = (HasCfg subApi c)

  route :: Proxy (CustomCombinator :> subApi) -> Config c
    -> Delayed (Server (CustomCombinator :> subApi))
    -> Router
  route Proxy config delayed =
    route subProxy config (fmap inject delayed :: Delayed (Server subApi))
    where
      subProxy :: Proxy subApi
      subProxy = Proxy

      inject :: (FromCombinator -> a) -> a
      inject f = f (FromCombinator "jujuju")

-- * API

type API =
  CustomCombinator :> Get '[JSON] String

api :: Proxy API
api = Proxy

testServer :: Server API
testServer (FromCombinator s) = return s

app :: Application
app = serve api EmptyConfig testServer

-- * tests

spec :: Spec
spec = do
  describe "using Config in a custom combinator" $ do
    with (return app) $ do
      it "allows to retrieve the ConfigEntry" $ do
        get "/" `shouldRespondWith` "bla"