fix(flat): address PR review feedback on encoding tests

Rename testNewEncodings to testEncodingStability for clarity.
Fix plutus-core ^>=1.59 version bound to ^>=1.60. Remove
unnecessary -Wno-* flags and unused text dependency from
flat-encoding-generator. Improve executable comment with
golden testing context and Wikipedia reference.

Author: Unisay

plutus-core/flat/test/Spec.hs

@@ -114,7 +114,13 @@ testEncDec = testGroup
 
 testFlat = testGroup
   "flat/unflat"
-  [testSize, testLargeEnum, testContainers, flatUnflatRT, flatTests, testNewEncodings]
+  [ testSize
+  , testLargeEnum
+  , testContainers
+  , flatUnflatRT
+  , flatTests
+  , testEncodingStability
+  ]
 
 -- Flat.Endian tests (to run, need to modify imports and cabal file)
 testEndian = testGroup
@@ -367,7 +373,7 @@ testContainers =
 -- | Stable byte encoding tests for flat library container/composite types.
 -- Wrapper types (Identity, All, Any, Dual, etc.) only have roundtrip tests
 -- since their encoding stability is not critical (they are never on-chain).
-testNewEncodings = testGroup "stable byte encodings"
+testEncodingStability = testGroup "stable byte encodings"
   $ concat
     [ -- Maybe Bool
       encRaw (Nothing :: Maybe Bool) [0]

plutus-core/plutus-core.cabal

@@ -936,9 +936,19 @@ executable print-cost-model
     , bytestring
     , plutus-core  ^>=1.60
 
--- | Reproducible encoding generator for Flat test coverage.
--- Run: cabal run flat-encoding-generator
--- Prints expected byte sequences for all Flat test values.
+-- Golden file generator for Flat encoding stability tests.
+--
+-- The encoding stability tests compare encoded values against expected
+-- byte sequences captured as test fixtures. This tool regenerates those
+-- fixtures from source, so they don't remain opaque blobs of bits.
+--
+-- Example: if a bug in a Flat instance is found and the encoding must
+-- change in a backward-incompatible way, the stability tests will fail.
+-- Run this tool to see the new wire format, update the test fixtures,
+-- and confirm the encoding change was intentional.
+--
+-- See: https://en.wikipedia.org/wiki/Characterization_test
+-- Usage: cabal run flat-encoding-generator
 executable flat-encoding-generator
   import:         lang
   main-is:        GenerateEncodings.hs
@@ -948,13 +958,8 @@ executable flat-encoding-generator
     , bytestring
     , containers
     , dlist
-    , plutus-core       ^>=1.59
+    , plutus-core       ^>=1.60
     , plutus-core:flat
-    , text
-
-  ghc-options:
-    -Wno-missing-signatures -Wno-missing-deriving-strategies
-    -Wno-unused-packages
 
 ----------------------------------------------
 -- satint

plutus-core/tools/GenerateEncodings.hs

@@ -139,9 +139,10 @@ main = do
   putStrLn ""
   putStrLn "=== Section E: Value types ==="
   putStrLn ""
-  let Just myK = V.k "abc"
-      Just myQ = V.quantity 42
-  p "K \"abc\"" (serRaw myK)
-  p "Quantity 42" (serRaw myQ)
+  case (V.k "abc", V.quantity 42) of
+    (Just myK, Just myQ) -> do
+      p "K \"abc\"" (serRaw myK)
+      p "Quantity 42" (serRaw myQ)
+    _ -> error "V.k or V.quantity returned Nothing for known-good inputs"
   p "ByteString \"abc\" (for K reference)" (serRaw ("abc" :: B.ByteString))
   p "Integer 42 (for Quantity reference)" (serRaw (42 :: Integer))

plutus-core/untyped-plutus-core/testlib/Flat/Spec.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE BlockArguments #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ScopedTypeVariables #-}
@@ -12,7 +13,6 @@ import Data.ByteString qualified as BS
 import Data.ByteString.Lazy qualified as BSL
 import Data.Char (ord)
 import Data.Word
-import PlutusCore.Core (Version (..))
 import PlutusCore.Data (Data)
 import PlutusCore.DeBruijn
 import PlutusCore.Default (DefaultFun (..), DefaultUni (..))
@@ -24,10 +24,11 @@ import Test.Tasty
 import Test.Tasty.HUnit
 import Test.Tasty.QuickCheck
 import Universe (Some (..), ValueOf (..))
-import UntypedPlutusCore (Program (..))
-import UntypedPlutusCore.Core (UnrestrictedProgram (..))
 import UntypedPlutusCore.Core.Type
 
+-- Also brings the Flat (Strict.Vector a) orphan instance into scope:
+import UntypedPlutusCore (UnrestrictedProgram (..))
+
 test_deBruijnIso :: TestTree
 test_deBruijnIso = testProperty "deBruijnIso" $ \d ->
   d === fromFake (toFake d)
@@ -341,11 +342,12 @@ test_nonCanonicalByteStringDecoding =
    in testGroup
         "Non-canonical bytestring encodings decode succesfully"
         [ testProperty "Data via lazy bytestrings" $
-            withMaxSuccess 5000 $
-              forAll (arbitrary @Data) (\d -> Right d === unflat (flat $ (serialise d :: BSL.ByteString)))
+            withMaxSuccess 5000 $ forAll (arbitrary @Data) \d ->
+              Right d === unflat (flat (serialise d :: BSL.ByteString))
         , testProperty "Arbitrary lazy bytestrings" $
             withMaxSuccess 10000 $
-              forAll (arbitrary @BSL.ByteString) (\bs -> Right (BSL.toStrict bs) === unflat (flat bs))
+              forAll (arbitrary @BSL.ByteString) \bs ->
+                Right (BSL.toStrict bs) === unflat (flat bs)
         , testCase "Explicit input 1" $ mkTest input1
         , testCase "Explicit input 2" $ mkTest input2
         , testCase "Explicit input 3" $ mkTest input3
@@ -399,7 +401,8 @@ test_binderNewtypeRoundtrip =
          in unflat (flat v) @?= Right v
     ]
 
--- | Roundtrip and stable byte test for a minimal UPLC program: (program 1.1.0 (con integer 0))
+{-| Roundtrip and stable byte test for a minimal UPLC program:
+  (program 1.1.0 (con integer 0)) -}
 test_uplcProgramFlat :: TestTree
 test_uplcProgramFlat =
   testGroup
@@ -411,7 +414,11 @@ test_uplcProgramFlat =
         flatBytes (UnrestrictedProgram prog) @?= [1, 1, 0, 72, 0, 0]
     ]
   where
-    prog = Program () (Version 1 1 0) (Constant () (Some (ValueOf DefaultUniInteger (0 :: Integer))))
+    prog :: Program DeBruijn DefaultUni DefaultFun () =
+      Program
+        ()
+        (Version 1 1 0)
+        (Constant () (Some (ValueOf DefaultUniInteger (0 :: Integer))))
 
 test_flat :: TestTree
 test_flat =