Testing.md

Testing in Haskell with Servant

Repository https://github.com/algas/haskell-servant-cookbook

Test target

The following API returns "Simple" when you send a request to your server.

{-# LANGUAGE DataKinds         #-}
{-# LANGUAGE DeriveGeneric     #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeOperators     #-}
module SimpleApi where

import           Data.Aeson
import           Data.Proxy
import           Data.Text                  (Text)
import           GHC.Generics
import           Network.Wai
import           Servant
import           Servant.API

type SimpleAPI  = Get '[PlainText] Text

simpleApi :: Proxy SimpleAPI
simpleApi = Proxy

server :: Server SimpleAPI
server = return "Simple"

app :: Application
app = serve simpleApi server

Test code

Use with function in hspec-wai to call app function in SimpleApi

with :: IO a -> SpecWith a -> Spec

Test codes as following.

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes       #-}
module Main (main) where

import           SimpleApi           (app)
import           Test.Hspec
import           Test.Hspec.Wai
import           Test.Hspec.Wai.JSON

main :: IO ()
main = hspec spec

spec :: Spec
spec = with (return app) $ do
    describe "GET /" $ do
        it "responds with 200" $ do
            get "/" `shouldRespondWith` 200
        it "responds with 'Simple'" $ do
            get "/" `shouldRespondWith` "Simple"

test-suite test
  type:                exitcode-stdio-1.0
  hs-source-dirs:      test
  main-is:             Spec.hs
  build-depends:       base
                     , hspec
                     , hspec-wai
                     , hspec-wai-json
                     , aeson
                     , transformers
                     , haskell-servant-cookbook
  ghc-options:         -threaded -rtsopts -with-rtsopts=-N
  default-language:    Haskell2010

Usage

$ stack test

haskell-servant-cookbook-0.1.0.0: test (suite: test)

Progress: 1/2
GET /
  responds with 200
  responds with 'Simple'

Finished in 0.0138 seconds
2 examples, 0 failures

Completed 2 action(s).

Reference

https://github.com/commercialhaskell/stack-templates/blob/master/scotty-hspec-wai.hsfiles