ADD explicit error expectations for CollectCom

TODO: need to be explicit with the other mutations also
NOTE: note clear what the MutateHeadTransition is trying to exercise

hydra-node/test/Hydra/Chain/Direct/Contract/CollectCom.hs

@@ -167,7 +167,10 @@ data CollectComMutation
   | -- | Test that collectCom cannot collect from an initial UTxO.
     MutateCommitToInitial
   | MutateHeadTransition
-  | -- | Test that every party has a chance to commit.
+  | -- | Every party should have commited and taken into account for the collectCom transaction to be valid
+    --   Here we increase the number of parties in input and output but keep the commits unchanged. This
+    --   simulate the situation where one participant would not have commited already or whose commit would
+    --   have been ignored by the collectCom transaction.
     MutateNumberOfParties
   | MutateHeadId
   | MutateRequiredSigner
@@ -178,7 +181,7 @@ data CollectComMutation
 genCollectComMutation :: (Tx, UTxO) -> Gen SomeMutation
 genCollectComMutation (tx, _utxo) =
   oneof
-    [ SomeMutation Nothing MutateOpenUTxOHash . ChangeOutput 0 <$> mutateUTxOHash
+    [ SomeMutation (Just "incorrect utxo hash") MutateOpenUTxOHash . ChangeOutput 0 <$> mutateUTxOHash
     , SomeMutation Nothing MutateHeadTransition <$> do
         changeRedeemer <- ChangeHeadRedeemer <$> (Head.Close <$> arbitrary)
         differencCurrencySymbol <- arbitrary `suchThat` (/= toPlutusCurrencySymbol testPolicyId)
@@ -191,7 +194,7 @@ genCollectComMutation (tx, _utxo) =
                     <*> pure differencCurrencySymbol
                 )
         pure $ Changes [changeRedeemer, changeDatum]
-    , SomeMutation Nothing MutateNumberOfParties <$> do
+    , SomeMutation (Just "changed parameters") MutateNumberOfParties <$> do
         -- NOTE: This also mutates the contestation period becuase we could not
         -- be bothered to decode/lookup the current one.
         c <- arbitrary
@@ -201,14 +204,14 @@ genCollectComMutation (tx, _utxo) =
             [ ChangeInputHeadDatum $ Head.Initial c moreParties (toPlutusCurrencySymbol testPolicyId)
             , ChangeOutput 0 $ mutatedPartiesHeadTxOut moreParties headTxOut
             ]
-    , SomeMutation Nothing MutateHeadId <$> do
+    , SomeMutation (Just "ST not spent in transaction") MutateHeadId <$> do
         illedHeadResolvedInput <-
           mkHeadOutput
             <$> pure testNetworkId
             <*> fmap headPolicyId (arbitrary `suchThat` (/= testSeedInput))
             <*> pure (toUTxOContext $ mkTxOutDatum healthyCollectComInitialDatum)
         return $ ChangeInput healthyHeadInput illedHeadResolvedInput (Just $ toScriptData Head.CollectCom)
-    , SomeMutation Nothing MutateRequiredSigner <$> do
+    , SomeMutation (Just "signer is not a participant") MutateRequiredSigner <$> do
         newSigner <- verificationKeyHash <$> genVerificationKey
         pure $ ChangeRequiredSigners [newSigner]
     , SomeMutation Nothing MutateCommitToInitial <$> do

hydra-plutus/src/Hydra/Contract/Util.hs

@@ -20,10 +20,11 @@ hydraHeadV1 = "HydraHeadV1"
 -- 'CurrencySymbol' and 'TokenName' of 'hydraHeadV1'
 hasST :: CurrencySymbol -> Value -> Bool
 hasST headPolicyId v =
-  isJust $
-    find
-      (\(cs, tokenMap) -> cs == headPolicyId && hasHydraToken tokenMap)
-      (Map.toList $ getValue v)
+  traceIfFalse "ST not spent in transaction" $
+    isJust $
+      find
+        (\(currencySymbol, tokenMap) -> currencySymbol == headPolicyId && hasHydraToken tokenMap)
+        (Map.toList $ getValue v)
  where
   hasHydraToken tm =
     isJust $ find (\(tn, q) -> q == 1 && TokenName hydraHeadV1 == tn) (Map.toList tm)