No orphan arbitrary in hydra-tx (#1596)

Removes orphan `Arbitrary` instances of our own data types.

Different than functions, type class instances are not explicitly
imported and cannot be looked up easily through tooling. Hence, any
orphan instance is a pain to find if needed. We should try to not
introduce orphan instances we can easily avoid.

hydra-node/bench/tx-cost/TxCost.hs

@@ -59,10 +59,10 @@ import Hydra.Ledger.Cardano.Evaluate (
  )
 import Hydra.Ledger.Cardano.Time (slotNoFromUTCTime)
 import Hydra.Plutus.Orphans ()
+import Hydra.Tx.Snapshot (genConfirmedSnapshot)
 import PlutusLedgerApi.V2 (toBuiltinData)
 import PlutusTx.Builtins (lengthOfByteString, serialiseData)
 import Test.Hydra.Tx.Gen (genOutput, genUTxOAdaOnlyOfSize)
-import Test.Hydra.Tx.Snapshot (genConfirmedSnapshot)
 import Test.QuickCheck (generate)
 
 computeInitCost :: IO [(NumParties, TxSize, MemUnit, CpuUnit, Coin)]

hydra-node/src/Hydra/Chain.hs

@@ -34,7 +34,6 @@ import Hydra.Tx (
  )
 import Hydra.Tx.OnChainId (OnChainId)
 import Test.Cardano.Ledger.Core.Arbitrary ()
-import Test.Hydra.Tx ()
 import Test.Hydra.Tx.Gen (ArbitraryIsTx)
 import Test.QuickCheck.Instances.Semigroup ()
 import Test.QuickCheck.Instances.Time ()

hydra-node/src/Hydra/Chain/Direct/State.hs

@@ -107,6 +107,7 @@ import Hydra.Tx.Decrement (decrementTx)
 import Hydra.Tx.Fanout (fanoutTx)
 import Hydra.Tx.Init (initTx)
 import Hydra.Tx.OnChainId (OnChainId)
+import Hydra.Tx.Snapshot (genConfirmedSnapshot)
 import Hydra.Tx.Utils (splitUTxO, verificationKeyToOnChainId)
 import Test.Hydra.Tx.Gen (
   genOneUTxOFor,
@@ -116,7 +117,6 @@ import Test.Hydra.Tx.Gen (
   genUTxOAdaOnlyOfSize,
   genVerificationKey,
  )
-import Test.Hydra.Tx.Snapshot (genConfirmedSnapshot)
 import Test.QuickCheck (choose, frequency, oneof, suchThat, vector)
 import Test.QuickCheck.Gen (elements)
 import Test.QuickCheck.Modifiers (Positive (Positive))

hydra-node/src/Hydra/Chain/Direct/Tx.hs

@@ -46,7 +46,6 @@ import Hydra.Tx.OnChainId (OnChainId (..))
 import Hydra.Tx.Utils (assetNameToOnChainId, findFirst, hydraHeadV1AssetName, hydraMetadataLabel)
 import PlutusLedgerApi.V2 (CurrencySymbol, fromBuiltin)
 import PlutusLedgerApi.V2 qualified as Plutus
-import Test.Hydra.Tx ()
 import Test.Hydra.Tx.Gen ()
 import Test.QuickCheck (vectorOf)
 

hydra-node/src/Hydra/HeadLogic/State.hs

@@ -22,7 +22,6 @@ import Hydra.Tx.Snapshot (
   SnapshotNumber,
   SnapshotVersion,
  )
-import Test.Hydra.Tx ()
 import Test.Hydra.Tx.Gen (ArbitraryIsTx)
 
 -- | The main state of the Hydra protocol state machine. It holds both, the

hydra-node/src/Hydra/Network/Message.hs

@@ -16,7 +16,6 @@ import Hydra.Tx (
   UTxOType,
  )
 import Hydra.Tx.Crypto (Signature)
-import Test.Hydra.Tx ()
 import Test.Hydra.Tx.Gen (ArbitraryIsTx)
 
 data NetworkEvent msg

hydra-tx/hydra-tx.cabal

@@ -114,12 +114,9 @@ library testlib
   hs-source-dirs:  testlib
   visibility:      public
   exposed-modules:
-    Test.Hydra.Tx
     Test.Hydra.Tx.Fixture
     Test.Hydra.Tx.Gen
-    Test.Hydra.Tx.HeadId
     Test.Hydra.Tx.Mutation
-    Test.Hydra.Tx.Snapshot
 
   other-modules:   Paths_hydra_tx
   build-depends:

hydra-tx/src/Hydra/Tx/HeadId.hs

@@ -4,13 +4,17 @@ module Hydra.Tx.HeadId where
 
 import Hydra.Prelude
 
+import Data.ByteString qualified as BS
 import Hydra.Cardano.Api (
   HasTypeProxy (..),
   PolicyId,
   SerialiseAsRawBytes (..),
   UsingRawBytesHex (..),
  )
 import PlutusLedgerApi.V2 (CurrencySymbol (..), toBuiltin)
+import Test.QuickCheck (vectorOf)
+import Test.QuickCheck.Instances.Semigroup ()
+import Test.QuickCheck.Instances.Time ()
 
 -- | Uniquely identifies a Hydra Head.
 newtype HeadId = UnsafeHeadId ByteString
@@ -26,6 +30,9 @@ instance HasTypeProxy HeadId where
   data AsType HeadId = AsHeadId
   proxyToAsType _ = AsHeadId
 
+instance Arbitrary HeadId where
+  arbitrary = UnsafeHeadId . BS.pack <$> vectorOf 16 arbitrary
+
 -- | Unique seed to create a 'HeadId'
 --
 -- XXX: This might actually be the 'HeadId' to the protocol and users? Then the
@@ -44,6 +51,9 @@ instance HasTypeProxy HeadSeed where
   data AsType HeadSeed = AsHeadSeed
   proxyToAsType _ = AsHeadSeed
 
+instance Arbitrary HeadSeed where
+  arbitrary = UnsafeHeadSeed . BS.pack <$> vectorOf 16 arbitrary
+
 headIdToCurrencySymbol :: HeadId -> CurrencySymbol
 headIdToCurrencySymbol (UnsafeHeadId headId) = CurrencySymbol (toBuiltin headId)
 

hydra-tx/src/Hydra/Tx/Party.hs

@@ -24,6 +24,7 @@ import Hydra.Tx.Crypto (AsType (AsHydraKey), HydraKey)
 newtype Party = Party {vkey :: VerificationKey HydraKey}
   deriving stock (Eq, Show, Generic)
   deriving anyclass (ToJSON, FromJSON)
+  deriving newtype (Arbitrary)
 
 instance ToJSONKey Party where
   toJSONKey = toJSONKeyText (serialiseToRawBytesHexText . vkey)
@@ -43,9 +44,6 @@ instance Ord Party where
   Party{vkey = a} <= Party{vkey = b} =
     verificationKeyHash a <= verificationKeyHash b
 
-instance Arbitrary Party where
-  arbitrary = Party <$> arbitrary
-
 instance FromCBOR Party where
   fromCBOR = Party <$> fromCBOR
 

hydra-tx/src/Hydra/Tx/Snapshot.hs

@@ -9,18 +9,21 @@ import Cardano.Crypto.Util (SignableRepresentation (..))
 import Codec.Serialise (serialise)
 import Data.Aeson (object, withObject, (.:), (.:?), (.=))
 import Data.ByteString.Lazy qualified as LBS
-import Hydra.Cardano.Api (SerialiseAsRawBytes (..))
+import Hydra.Cardano.Api (SerialiseAsRawBytes (..), SigningKey)
 import Hydra.Contract.HeadState qualified as Onchain
-import Hydra.Tx.Crypto (MultiSignature)
+import Hydra.Tx.Crypto (HydraKey, MultiSignature, aggregate, sign)
 import Hydra.Tx.HeadId (HeadId)
 import Hydra.Tx.IsTx (IsTx (..))
 import PlutusLedgerApi.V2 (toBuiltin, toData)
+import Test.QuickCheck (frequency, suchThat)
 import Test.QuickCheck.Instances.Natural ()
 
+-- * SnapshotNumber and SnapshotVersion
+
 newtype SnapshotNumber
   = UnsafeSnapshotNumber Natural
   deriving stock (Eq, Ord, Generic)
-  deriving newtype (Show, ToJSON, FromJSON, ToCBOR, FromCBOR, Real, Num, Enum, Integral)
+  deriving newtype (Show, ToJSON, FromJSON, ToCBOR, FromCBOR, Real, Num, Enum, Integral, Arbitrary)
 
 -- NOTE: On-chain scripts ensure snapshot number does not become negative.
 fromChainSnapshotNumber :: Onchain.SnapshotNumber -> SnapshotNumber
@@ -30,13 +33,15 @@ fromChainSnapshotNumber =
 newtype SnapshotVersion
   = UnsafeSnapshotVersion Natural
   deriving stock (Eq, Ord, Generic)
-  deriving newtype (Show, ToJSON, FromJSON, ToCBOR, FromCBOR, Real, Num, Enum, Integral)
+  deriving newtype (Show, ToJSON, FromJSON, ToCBOR, FromCBOR, Real, Num, Enum, Integral, Arbitrary)
 
 -- NOTE: On-chain scripts ensure snapshot version does not become negative.
 fromChainSnapshotVersion :: Onchain.SnapshotVersion -> SnapshotVersion
 fromChainSnapshotVersion =
   UnsafeSnapshotVersion . fromMaybe 0 . integerToNatural
 
+-- * Snapshot
+
 data Snapshot tx = Snapshot
   { headId :: HeadId
   , version :: SnapshotVersion
@@ -54,6 +59,17 @@ data Snapshot tx = Snapshot
 deriving stock instance IsTx tx => Eq (Snapshot tx)
 deriving stock instance IsTx tx => Show (Snapshot tx)
 
+-- | Binary representation of snapshot signatures. That is, concatenated CBOR for
+-- 'headId', 'version', 'number', 'utxoHash' and 'utxoToDecommitHash' according
+-- to CDDL schemata:
+--
+-- headId = bytes .size 16
+-- version = uint
+-- number = uint
+-- utxoHash = bytes
+-- utxoToDecommitHash = bytes
+--
+-- where hashes are the result of applying 'hashUTxO'.
 instance forall tx. IsTx tx => SignableRepresentation (Snapshot tx) where
   getSignableRepresentation Snapshot{headId, version, number, utxo, utxoToDecommit} =
     LBS.toStrict $
@@ -106,6 +122,19 @@ instance (Typeable tx, FromCBOR (UTxOType tx), FromCBOR (TxIdType tx)) => FromCB
       <*> fromCBOR
       <*> fromCBOR
 
+instance (Arbitrary (UTxOType tx), Arbitrary (TxIdType tx)) => Arbitrary (Snapshot tx) where
+  arbitrary = genericArbitrary
+
+  -- NOTE: See note on 'Arbitrary (ClientInput tx)'
+  shrink Snapshot{headId, version, number, utxo, confirmed, utxoToDecommit} =
+    [ Snapshot headId version number confirmed' utxo' utxoToDecommit'
+    | confirmed' <- shrink confirmed
+    , utxo' <- shrink utxo
+    , utxoToDecommit' <- shrink utxoToDecommit
+    ]
+
+-- * ConfirmedSnapshot
+
 -- | A snapshot that can be used to close a head with. Either the initial one,
 -- or when it was signed by all parties, i.e. it is confirmed.
 data ConfirmedSnapshot tx
@@ -121,13 +150,13 @@ data ConfirmedSnapshot tx
   deriving stock (Generic, Eq, Show)
   deriving anyclass (ToJSON, FromJSON)
 
+-- | Safely get a 'Snapshot' from a confirmed snapshot.
+--
 -- NOTE: While we could use 'snapshot' directly, this is a record-field accessor
 -- which may become partial (and lead to unnoticed runtime errors) if we ever
 -- add a new branch to the sumtype. So, we explicitely define a getter which
 -- will force us into thinking about changing the signature properly if this
 -- happens.
-
--- | Safely get a 'Snapshot' from a confirmed snapshot.
 getSnapshot :: ConfirmedSnapshot tx -> Snapshot tx
 getSnapshot = \case
   InitialSnapshot{headId, initialUTxO} ->
@@ -147,3 +176,48 @@ isInitialSnapshot :: ConfirmedSnapshot tx -> Bool
 isInitialSnapshot = \case
   InitialSnapshot{} -> True
   ConfirmedSnapshot{} -> False
+
+instance (Arbitrary (UTxOType tx), Arbitrary (TxIdType tx), IsTx tx) => Arbitrary (ConfirmedSnapshot tx) where
+  arbitrary = do
+    ks <- arbitrary
+    utxo <- arbitrary
+    utxoToDecommit <- arbitrary
+    headId <- arbitrary
+    genConfirmedSnapshot headId 0 0 utxo utxoToDecommit ks
+
+  shrink = \case
+    InitialSnapshot hid sn -> [InitialSnapshot hid sn' | sn' <- shrink sn]
+    ConfirmedSnapshot sn sigs -> ConfirmedSnapshot <$> shrink sn <*> shrink sigs
+
+genConfirmedSnapshot ::
+  IsTx tx =>
+  HeadId ->
+  -- | Exact snapshot version to generate.
+  SnapshotVersion ->
+  -- | The lower bound on snapshot number to generate.
+  -- If this is 0, then we can generate an `InitialSnapshot` or a `ConfirmedSnapshot`.
+  -- Otherwise we generate only `ConfirmedSnapshot` with a number strictly superior to
+  -- this lower bound.
+  SnapshotNumber ->
+  UTxOType tx ->
+  Maybe (UTxOType tx) ->
+  [SigningKey HydraKey] ->
+  Gen (ConfirmedSnapshot tx)
+genConfirmedSnapshot headId version minSn utxo utxoToDecommit sks
+  | minSn > 0 = confirmedSnapshot
+  | otherwise =
+      frequency
+        [ (1, initialSnapshot)
+        , (9, confirmedSnapshot)
+        ]
+ where
+  initialSnapshot =
+    InitialSnapshot <$> arbitrary <*> pure utxo
+
+  confirmedSnapshot = do
+    -- FIXME: This is another nail in the coffin to our current modeling of
+    -- snapshots
+    number <- arbitrary `suchThat` (> minSn)
+    let snapshot = Snapshot{headId, version, number, confirmed = [], utxo, utxoToDecommit}
+    let signatures = aggregate $ fmap (`sign` snapshot) sks
+    pure $ ConfirmedSnapshot{snapshot, signatures}

hydra-tx/src/Hydra/Tx/Utils.hs

@@ -1,5 +1,3 @@
-{-# OPTIONS_GHC -Wno-orphans #-}
-
 module Hydra.Tx.Utils where
 
 import Hydra.Cardano.Api

hydra-tx/test/Hydra/Tx/Contract/Close/CloseUnused.hs

@@ -61,7 +61,6 @@ import Test.Hydra.Tx.Mutation (
   replaceSnapshotVersion,
   replaceUTxOHash,
  )
-import Test.Hydra.Tx.Snapshot ()
 import Test.QuickCheck (arbitrarySizedNatural, choose, elements, listOf1, oneof, resize, suchThat)
 import Test.QuickCheck.Instances ()
 

hydra-tx/test/Hydra/Tx/Contract/Close/CloseUsed.hs

@@ -44,7 +44,6 @@ import Hydra.Tx.Contract.Close.Healthy (
   somePartyCardanoVerificationKey,
  )
 import Hydra.Tx.Crypto (MultiSignature (..), toPlutusSignatures)
-import Hydra.Tx.Snapshot ()
 import PlutusLedgerApi.V1.Time (DiffMilliSeconds (..), fromMilliSeconds)
 import PlutusLedgerApi.V2 (POSIXTime, PubKeyHash (PubKeyHash), toBuiltin)
 import Test.Hydra.Tx.Fixture qualified as Fixture
@@ -71,7 +70,6 @@ import Test.Hydra.Tx.Mutation (
   replaceSnapshotVersion,
   replaceUTxOHash,
  )
-import Test.Hydra.Tx.Snapshot ()
 import Test.QuickCheck (arbitrarySizedNatural, choose, elements, listOf1, oneof, suchThat)
 import Test.QuickCheck.Instances ()
 

hydra-tx/test/Hydra/Tx/Contract/Contest/ContestCurrent.hs

@@ -34,7 +34,6 @@ import Hydra.Tx.Utils (
  )
 import PlutusLedgerApi.V2 (BuiltinByteString, toBuiltin)
 import PlutusLedgerApi.V2 qualified as Plutus
-import Test.Hydra.Tx ()
 import Test.Hydra.Tx.Fixture (aliceSk, bobSk, carolSk, slotLength, systemStart, testNetworkId, testPolicyId)
 import Test.Hydra.Tx.Fixture qualified as Fixture
 import Test.Hydra.Tx.Gen (

hydra-tx/test/Hydra/Tx/Contract/Decrement.hs

@@ -37,7 +37,6 @@ import Hydra.Tx.Utils (adaOnly, splitUTxO)
 import PlutusTx.Builtins (toBuiltin)
 import Test.Hydra.Tx.Fixture (aliceSk, bobSk, carolSk, testNetworkId, testPolicyId)
 import Test.Hydra.Tx.Gen (genForParty, genScriptRegistry, genUTxOSized, genValue, genVerificationKey)
-import Test.Hydra.Tx.Snapshot ()
 import Test.QuickCheck (arbitrarySizedNatural, choose, elements, oneof)
 import Test.QuickCheck.Gen (suchThat)
 import Test.QuickCheck.Instances ()

hydra-tx/testlib/Test/Hydra/Tx.hs

@@ -1,4 +1 @@
 module Test.Hydra.Tx where
-
-import Test.Hydra.Tx.HeadId ()
-import Test.Hydra.Tx.Snapshot ()

hydra-tx/testlib/Test/Hydra/Tx/Fixture.hs

@@ -1,5 +1,4 @@
 {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
-{-# OPTIONS_GHC -Wno-orphans #-}
 
 -- | Generic Cardano constants for use in testing.
 module Test.Hydra.Tx.Fixture (