Recalculate aux data hash on conversion and test it

On each conversion we need to recalculate the aux data hash since
cardano-api does not provide a way to set the data hash and on top of
it it seems that it removes it completely.

Add a roundtrip test to assert the metadata is correctly converted.

hydra-cardano-api/src/Hydra/Cardano/Api/Tx.hs

@@ -227,7 +227,6 @@ toLedgerTx = \case
             & datsTxWitsL .~ datums
             & rdmrsTxWitsL .~ redeemers
      in mkBasicTx
-          -- TODO: Test that aux data hash is correctly updated in conversions
           (body & auxDataHashTxBodyL .~ maybe SNothing (SJust . hashTxAuxData) auxData)
           & isValidTxL .~ toLedgerScriptValidity validity
           & auxDataTxL .~ maybeToStrictMaybe auxData
@@ -237,12 +236,13 @@ toLedgerTx = \case
 fromLedgerTx :: Ledger.Tx (ShelleyLedgerEra Era) -> Tx Era
 fromLedgerTx ledgerTx =
   Tx
-    (ShelleyTxBody shelleyBasedEra body scripts scriptsData (strictMaybeToMaybe auxData) validity)
+    (ShelleyTxBody shelleyBasedEra body' scripts scriptsData (strictMaybeToMaybe auxData) validity)
     (fromLedgerTxWitness wits)
  where
   -- XXX: The suggested way (by the ledger team) forward is to use lenses to
   -- introspect ledger transactions.
   Ledger.AlonzoTx body wits isValid auxData = ledgerTx
+  body' = body & auxDataHashTxBodyL .~ (hashTxAuxData <$> auxData)
 
   scripts =
     Map.elems $ Ledger.txscripts' wits

hydra-node/test/Hydra/Ledger/CardanoSpec.hs

@@ -8,9 +8,11 @@ import Hydra.Prelude
 import Test.Hydra.Prelude
 
 import Cardano.Binary (decodeFull, serialize')
-import Cardano.Ledger.Api (ensureMinCoinTxOut)
+import Cardano.Ledger.Api (auxDataHashTxBodyL, bodyTxL, ensureMinCoinTxOut)
+import Cardano.Ledger.BaseTypes (StrictMaybe (..))
 import Cardano.Ledger.Core (PParams ())
 import Cardano.Ledger.Credential (Credential (..))
+import Control.Lens ((.~))
 import Data.Aeson (eitherDecode, encode)
 import Data.Aeson qualified as Aeson
 import Data.Aeson.Lens (key)
@@ -71,6 +73,8 @@ spec =
 
       prop "Roundtrip to and from Ledger" roundtripLedger
 
+      prop "Roundtrip tx metadata" roundtripTxMetadata
+
       prop "Roundtrip CBOR encoding" $ roundtripCBOR @Tx
 
       prop "JSON encoding of Tx according to schema" $
@@ -152,6 +156,10 @@ roundtripLedger :: Tx -> Property
 roundtripLedger tx =
   fromLedgerTx (toLedgerTx tx) === tx
 
+roundtripTxMetadata :: Tx -> Property
+roundtripTxMetadata tx =
+  fromLedgerTx (toLedgerTx tx & bodyTxL . auxDataHashTxBodyL .~ SNothing) === tx
+
 roundtripCBOR :: (Eq a, Show a, ToCBOR a, FromCBOR a) => a -> Property
 roundtripCBOR a =
   let encoded = serialize' a