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{-# LANGUAGE OverloadedStrings, DeriveGeneric #-}
module Regression.Issue571 (issue571) where
import Test.Tasty (TestTree)
import Test.Tasty.HUnit (testCase, (@?=))
import GHC.Generics (Generic)
import Data.Aeson
data F = F
{ a :: Maybe Int
, b :: Maybe Int
, c :: ()
}
deriving (Eq, Show, Generic)
instance FromJSON F where
parseJSON = genericParseJSON defaultOptions { omitNothingFields = False } -- default
data G = G
{ e :: Maybe Int
, f :: Maybe Int
, g :: ()
}
deriving (Eq, Show, Generic)
instance FromJSON G where
parseJSON = genericParseJSON defaultOptions { omitNothingFields = False, allowOmittedFields = False }
issue571 :: TestTree
issue571 = testCase "issue571" $ do
-- the Maybe fields can be omitted.
let actualF = decode "{}" :: Maybe F
actualF @?= Just F { a = Nothing, b = Nothing, c = () }
(decode "{}" :: Maybe G) @?= Nothing
(decode "{\"e\":1, \"f\":2}" :: Maybe G) @?= Nothing
(decode "{\"e\":1, \"g\":[]}" :: Maybe G) @?= Nothing
(decode "{\"f\":2, \"g\":[]}" :: Maybe G) @?= Nothing
(decode "{\"e\":1, \"f\":2, \"g\":[]}" :: Maybe G) @?= Just G { e = Just 1, f = Just 2, g = () }
(decode "{\"e\":1, \"f\":2, \"g\":true}" :: Maybe G) @?= Just G { e = Just 1, f = Just 2, g = () }
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