Add tests for isValidUtf8ByteString and isValidUtf8ByteArray

tests/Tests/Properties.hs

@@ -16,6 +16,7 @@ import Tests.Properties.Substrings (testSubstrings)
 import Tests.Properties.Read (testRead)
 import Tests.Properties.Text (testText)
 import Tests.Properties.Transcoding (testTranscoding)
+import Tests.Properties.Validate (testValidate)
 
 tests :: TestTree
 tests =
@@ -28,5 +29,6 @@ tests =
     testSubstrings,
     testBuilder,
     testLowLevel,
-    testRead
+    testRead,
+    testValidate
   ]

tests/Tests/Properties/Validate.hs

@@ -0,0 +1,47 @@
+{-# LANGUAGE CPP #-}
+module Tests.Properties.Validate (testValidate) where
+
+import Data.Array.Byte (ByteArray)
+import Data.ByteString (ByteString)
+import qualified Data.ByteString as B
+import Data.ByteString.Short (toShort)
+import Data.Either (isRight)
+import Data.Text.Encoding (decodeUtf8', encodeUtf8)
+import Data.Text.Internal.Validate (isValidUtf8ByteString, isValidUtf8ByteArray)
+import Test.Tasty (TestTree, testGroup)
+import Test.Tasty.QuickCheck ((===), Gen, Property,
+  testProperty, arbitrary, forAllShrink, oneof, shrink)
+import Tests.QuickCheckUtils ()
+#if MIN_VERSION_bytestring(0,12,0)
+import Data.ByteString.Short (unShortByteString)
+#else
+import Data.ByteString.Short (ShortByteString(SBS))
+import Data.Array.Byte (ByteArray(ByteArray))
+
+unShortByteString :: ShortByteString -> ByteArray
+unShortByteString (SBS ba) = ByteArray ba
+#endif
+
+testValidate :: TestTree
+testValidate = testGroup "validate"
+  [ testProperty "bytestring" $ forAllShrink genByteString shrink $ \bs ->
+      isValidUtf8ByteString bs === isRight (decodeUtf8' bs)
+    -- We have all we need to shrink here but I'm too lazy to do that now.
+  , testProperty "bytearray" $ forAllByteArray $ \ba off len bs ->
+      isValidUtf8ByteArray ba off len === isRight (decodeUtf8' bs)
+  ]
+
+genByteString :: Gen ByteString
+genByteString = oneof
+  [ arbitrary
+  , encodeUtf8 <$> arbitrary
+  ]
+
+-- | We want to test 'isValidUtf8ByteArray' with various offsets, so we insert a random
+-- prefix and remember its length.
+forAllByteArray :: (ByteArray -> Int -> Int -> ByteString -> Property) -> Property
+forAllByteArray prop =
+  forAllShrink genByteString shrink $ \mainSlice ->
+  forAllShrink arbitrary shrink $ \prefix ->
+  let bs2ba = unShortByteString . toShort in
+  prop (bs2ba (prefix `B.append` mainSlice)) (B.length prefix) (B.length mainSlice) mainSlice

text.cabal

@@ -275,6 +275,7 @@ test-suite tests
     Tests.Properties.Substrings
     Tests.Properties.Text
     Tests.Properties.Transcoding
+    Tests.Properties.Validate
     Tests.QuickCheckUtils
     Tests.RebindableSyntaxTest
     Tests.Regressions
@@ -295,7 +296,8 @@ test-suite tests
     template-haskell,
     transformers,
     text
-
+  if impl(ghc < 9.4)
+    build-depends: data-array-byte >= 0.1 && < 0.2
   -- Plugin infrastructure does not work properly in 8.6.1, and
   -- ghc-9.2.1 library depends on parsec, which causes a circular dependency.
   if impl(ghc >= 8.2.1 && < 8.6 || >= 8.6.2 && < 9.2 || >= 9.2.2)