@@ -96,3 +96,4 @@
 [Coordinator.Debug]
 BatchPath = "/tmp/iden3-test/hermez/batchesdebug"
 LightScrypt = true
+# RollupVerifierIndex = 0

@@ -90,7 +90,6 @@ Path string `validate:"required"`
 	} `validate:"required"`
 	ServerProofs []ServerProof `validate:"required"`
 	Circuit      struct {
-		// VerifierIdx uint8  `validate:"required"`
 		// MaxTx is the maximum number of txs supported by the circuit
 		MaxTx int64 `validate:"required"`
 		// NLevels is the maximum number of merkle tree levels
@@ -132,6 +131,10 @@ BatchPath string
 		// LightScrypt if set, uses light parameters for the ethereum
 		// keystore encryption algorithm.
 		LightScrypt bool
+		// RollupVerifierIndex is the index of the verifier to use in
+		// the Rollup smart contract.  The verifier chosen by index
+		// must match with the Circuit parameters.
+		RollupVerifierIndex *int
 	}
 }
 

@@ -799,14 +799,14 @@
 // AuctionEventsByBlock returns the events in a block that happened in the
 // Auction Smart Contract.
 // To query by blockNum, set blockNum >= 0 and blockHash == nil.
-// To query by blockHash, set blockNum == -1 and blockHash != nil.
+// To query by blockHash set blockHash != nil, and blockNum will be ignored.
 // If there are no events in that block the result is nil.
 func (c *AuctionClient) AuctionEventsByBlock(blockNum int64,
 	blockHash *ethCommon.Hash) (*AuctionEvents, error) {
 	var auctionEvents AuctionEvents
 
 	var blockNumBigInt *big.Int
-	if blockNum >= 0 {
+	if blockHash == nil {
 		blockNumBigInt = big.NewInt(blockNum)
 	}
 	query := ethereum.FilterQuery{

@@ -738,14 +738,14 @@
 // RollupEventsByBlock returns the events in a block that happened in the
 // Rollup Smart Contract.
 // To query by blockNum, set blockNum >= 0 and blockHash == nil.
-// To query by blockHash, set blockNum == -1 and blockHash != nil.
+// To query by blockHash set blockHash != nil, and blockNum will be ignored.
 // If there are no events in that block the result is nil.
 func (c *RollupClient) RollupEventsByBlock(blockNum int64,
 	blockHash *ethCommon.Hash) (*RollupEvents, error) {
 	var rollupEvents RollupEvents
 
 	var blockNumBigInt *big.Int
-	if blockNum >= 0 {
+	if blockHash == nil {
 		blockNumBigInt = big.NewInt(blockNum)
 	}
 	query := ethereum.FilterQuery{

@@ -426,14 +426,14 @@
 // WDelayerEventsByBlock returns the events in a block that happened in the
 // WDelayer Smart Contract.
 // To query by blockNum, set blockNum >= 0 and blockHash == nil.
-// To query by blockHash, set blockNum == -1 and blockHash != nil.
+// To query by blockHash set blockHash != nil, and blockNum will be ignored.
 // If there are no events in that block the result is nil.
 func (c *WDelayerClient) WDelayerEventsByBlock(blockNum int64,
 	blockHash *ethCommon.Hash) (*WDelayerEvents, error) {
 	var wdelayerEvents WDelayerEvents
 
 	var blockNumBigInt *big.Int
-	if blockNum >= 0 {
+	if blockHash == nil {
 		blockNumBigInt = big.NewInt(blockNum)
 	}
 	query := ethereum.FilterQuery{

@@ -252,14 +252,37 @@ ChainID:  chainIDU16,
 			MaxFeeTx: common.RollupConstMaxFeeIdxCoordinator,
 			MaxL1Tx:  common.RollupConstMaxL1Tx,
 		}
-		verifierIdx, err := scConsts.Rollup.FindVerifierIdx(
-			cfg.Coordinator.Circuit.MaxTx,
-			cfg.Coordinator.Circuit.NLevels,
-		)
-		if err != nil {
-			return nil, tracerr.Wrap(err)
+		var verifierIdx int
+		if cfg.Coordinator.Debug.RollupVerifierIndex == nil {
+			verifierIdx, err = scConsts.Rollup.FindVerifierIdx(
+				cfg.Coordinator.Circuit.MaxTx,
+				cfg.Coordinator.Circuit.NLevels,
+			)
+			if err != nil {
+				return nil, tracerr.Wrap(err)
+			}
+			log.Infow("Found verifier that matches circuit config", "verifierIdx", verifierIdx)
+		} else {
+			verifierIdx = *cfg.Coordinator.Debug.RollupVerifierIndex
+			log.Infow("Using debug verifier index from config", "verifierIdx", verifierIdx)
+			if verifierIdx >= len(scConsts.Rollup.Verifiers) {
+				return nil, tracerr.Wrap(
+					fmt.Errorf("verifierIdx (%v) >= "+
+						"len(scConsts.Rollup.Verifiers) (%v)",
+						verifierIdx, len(scConsts.Rollup.Verifiers)))
+			}
+			verifier := scConsts.Rollup.Verifiers[verifierIdx]
+			if verifier.MaxTx != cfg.Coordinator.Circuit.MaxTx ||
+				verifier.NLevels != cfg.Coordinator.Circuit.NLevels {
+				return nil, tracerr.Wrap(
+					fmt.Errorf("Circuit config and verifier params don't match.  "+
+						"circuit.MaxTx = %v, circuit.NLevels = %v, "+
+						"verifier.MaxTx = %v, verifier.NLevels = %v",
+						cfg.Coordinator.Circuit.MaxTx, cfg.Coordinator.Circuit.NLevels,
+						verifier.MaxTx, verifier.NLevels,
+					))
+			}
 		}
-		log.Infow("Found verifier that matches circuit config", "verifierIdx", verifierIdx)
 
 		coord, err = coordinator.NewCoordinator(
 			coordinator.Config{