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This is part of a series:
- Rewriting to Haskell–Intro
- Rewriting to Haskell–Project Setup
- Rewriting to Haskell–Deployment
- Rewriting to Haskell–Automatic Formatting
- Rewriting to Haskell–Configuration
- Rewriting to Haskell–Standing on the shoulders of Rails
- Rewriting to Haskell–Making GHC More Nitpicky
We have managed to delay testing by leaning on Ruby RSpec for a while. It's time to do the right thing and write some tests in Haskell.
We peaked at the "How To Test Servant Applications" cookbook page and decided to go the hspec-wai way. In fact, using servant-client seemed a bit too involved and coupled with Servant. The former, on the other hand, enables us to test any wai application.
With that in mind we created a test/Spec.hs:
main :: IO ()
main = do
setEnv "DATABASE" "stream_test"
-- ^ See https://odone.io/posts/2020-03-23-rewriting-haskell-configuration.html for the why.
application <- configuredApp
connection <- getConnection
hspec $ spec application connection
spec :: Application -> Connection -> Spec
spec application connection = with (pure application) $ after_ (truncateTables connection)
-- ^ After each spec item truncate tables.
$ describe "GET /servant/search"
$ do
it "with no query it returns all posts ordered by descending creation date" $ do
user <- liftIO . createUser $ connection
now <- liftIO randomUTCTime
let later = addUTCTime 1 now
let olderPostAttributes =
defaultPostAttributes
{ postAttributesUserId = userId user,
postAttributesCreatedAt = Just now
}
let newerPostAttributes = olderPostAttributes {postAttributesCreatedAt = Just later}
olderPost <- liftIO $ createPost connection olderPostAttributes
newerPost <- liftIO $ createPost connection newerPostAttributes
get "/servant/search"
`shouldRespondWith` [json|
-- ^ Using hspec-wai-json and some Template Haskell to generate JSON.
{ users: [#{user}],
-- ^ Behind the curtains aeson-qq is used. Thus, you can interpolate variables:
-- https://github.com/sol/aeson-qq#aeson-qq-json-quasiquoter-for-haskell
attachments: [],
comments: [],
posts: [#{newerPost}, #{olderPost}]
}
|]
-- ...
At the moment we are just testing through the endpoints as shown above. Stream is a simple application so we feel confident with this approach. Should the need for other types of tests arise, then HSpec will have our backs.
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