Allow min commitment of single state sync event

consensus/polybft/state_sync_manager.go

@@ -502,17 +502,14 @@ func (s *stateSyncManager) buildCommitment() error {
 	s.lock.Lock()
 	defer s.lock.Unlock()
 
-	epoch := s.epoch
-	fromIndex := s.nextCommittedIndex
-
-	stateSyncEvents, err := s.state.StateSyncStore.getStateSyncEventsForCommitment(fromIndex,
-		fromIndex+s.config.maxCommitmentSize-1)
+	stateSyncEvents, err := s.state.StateSyncStore.getStateSyncEventsForCommitment(s.nextCommittedIndex,
+		s.nextCommittedIndex+s.config.maxCommitmentSize-1)
 	if err != nil && !errors.Is(err, errNotEnoughStateSyncs) {
 		return fmt.Errorf("failed to get state sync events for commitment. Error: %w", err)
 	}
 
-	if len(stateSyncEvents) < minCommitmentSize {
-		// there is not enough state sync events to build at least the minimum commitment
+	if len(stateSyncEvents) == 0 {
+		// there are no state sync events
 		return nil
 	}
 
@@ -522,7 +519,7 @@ func (s *stateSyncManager) buildCommitment() error {
 		return nil
 	}
 
-	commitment, err := NewPendingCommitment(epoch, stateSyncEvents)
+	commitment, err := NewPendingCommitment(s.epoch, stateSyncEvents)
 	if err != nil {
 		return err
 	}
@@ -544,7 +541,7 @@ func (s *stateSyncManager) buildCommitment() error {
 		Signature: signature,
 	}
 
-	if _, err = s.state.StateSyncStore.insertMessageVote(epoch, hashBytes, sig); err != nil {
+	if _, err = s.state.StateSyncStore.insertMessageVote(s.epoch, hashBytes, sig); err != nil {
 		return fmt.Errorf(
 			"failed to insert signature for hash=%v to the state. Error: %w",
 			hex.EncodeToString(hashBytes),
@@ -557,7 +554,7 @@ func (s *stateSyncManager) buildCommitment() error {
 		Hash:        hashBytes,
 		Signature:   signature,
 		From:        s.config.key.String(),
-		EpochNumber: epoch,
+		EpochNumber: s.epoch,
 	})
 
 	s.logger.Debug(

consensus/polybft/state_transaction.go

@@ -218,16 +218,21 @@ func getCommitmentMessageSignedTx(txs []*types.Transaction) (*CommitmentMessageS
 }
 
 func createMerkleTree(stateSyncEvents []*contractsapi.StateSyncedEvent) (*merkle.MerkleTree, error) {
-	ssh := make([][]byte, len(stateSyncEvents))
+	stateSyncData := make([][]byte, len(stateSyncEvents))
 
 	for i, sse := range stateSyncEvents {
 		data, err := sse.EncodeAbi()
 		if err != nil {
 			return nil, err
 		}
 
-		ssh[i] = data
+		stateSyncData[i] = data
 	}
 
-	return merkle.NewMerkleTree(ssh)
+	if len(stateSyncEvents) == 1 {
+		//nolint:makezero
+		stateSyncData = append(stateSyncData, nil)
+	}
+
+	return merkle.NewMerkleTree(stateSyncData)
 }

e2e-polybft/e2e/bridge_test.go

@@ -184,7 +184,7 @@ func TestE2E_Bridge_Transfers(t *testing.T) {
 
 	t.Run("multiple deposit batches per epoch", func(t *testing.T) {
 		const (
-			depositsSubset = 2
+			depositsSubset = 1
 		)
 
 		initialBlockNum, err := childEthEndpoint.BlockNumber()