Simple arbitrary instances

.ghci

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+:set -itests

tests/Text/Digestive/Tests/Util.hs

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+module Text.Digestive.Tests.Util
+    ( Id (..)
+    ) where
+
+import Control.Applicative (Applicative (..), (<$>))
+import Test.QuickCheck (Arbitrary (..))
+
+import Text.Digestive.Result
+import Text.Digestive.Types
+
+-- | An ID Monad
+--
+newtype Id a = Id {unId :: a}
+
+instance Functor Id where
+    fmap f (Id x) = Id $ f x
+
+instance Applicative Id where
+    pure = Id
+    (Id f) <*> (Id x) = Id $ f x
+
+instance Monad Id where
+    return = Id
+    (Id x) >>= f = f x
+
+instance Arbitrary a => Arbitrary (Result e a) where
+    arbitrary = Ok <$> arbitrary
+
+instance Arbitrary v => Arbitrary (View e v) where
+    arbitrary = View . const <$> arbitrary
+
+instance (Monad m, Arbitrary v, Arbitrary a) => Arbitrary (Form m i e v a) where
+    arbitrary = do
+        v <- arbitrary
+        r <- arbitrary
+        return $ Form $ return (v, r)