feat(RPC): eth_simulateV1

CHANGELOG.md

@@ -39,6 +39,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 * (rpc) [#870](https://github.com/crypto-org-chain/ethermint/pull/870) fix(rpc): fix eth_getBlockReceipts crash
 * (ante) [#829](https://github.com/crypto-org-chain/ethermint/pull/829) fix: validate payload messages in legacy EIP-712
+* (rpc) [#869](https://github.com/crypto-org-chain/ethermint/pull/869) feat(RPC): implement `eth_simulateV1` RPC
 
 ## [v0.23.0] - 2026-01-13
 
@@ -59,7 +60,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (evm) [#809](https://github.com/crypto-org-chain/ethermint/pull/809) fix: relax preinstall rules
 * (rpc) [#814](https://github.com/crypto-org-chain/ethermint/pull/814) fix: estimate gas not accurate
 * (evm) [#815](https://github.com/crypto-org-chain/ethermint/pull/815) fix: nonce increments on EIP-7702 contract creation
-* (evm) [#822](https://github.com/crypto-org-chain/ethermint/pull/822) refactor:replace MsgEthereumTxResponse with EthCallResponse in EVM calls 
+* (evm) [#822](https://github.com/crypto-org-chain/ethermint/pull/822) refactor: replace MsgEthereumTxResponse with EthCallResponse in EVM calls
 
 ## [v0.22.0] - 2025-08-12
 

Makefile

@@ -540,3 +540,21 @@ localnet-show-logstream:
 	docker-compose logs --tail=1000 -f
 
 .PHONY: build-docker-local-ethermint localnet-start localnet-stop
+
+###############################################################################
+###                                Mocks                                    ###
+###############################################################################
+
+MOCKERY := go run github.com/vektra/mockery/v2@v2.53.0
+COMETBFT_DIR := $(shell go list -m -f '{{.Dir}}' github.com/cometbft/cometbft)
+
+mocks:
+	$(MOCKERY) --name "QueryClient" --structname "EVMQueryClient" \
+		--dir x/evm/types --output rpc/backend/mocks --outpkg mocks --filename evm_query_client.go
+	$(MOCKERY) --name "QueryClient" --structname "FeeMarketQueryClient" \
+		--dir x/feemarket/types --output rpc/backend/mocks --outpkg mocks --filename feemarket_query_client.go
+	$(MOCKERY) --name "Client" \
+		--dir $(COMETBFT_DIR)/rpc/client \
+		--output rpc/backend/mocks --outpkg mocks --filename client.go
+
+.PHONY: mocks

proto/ethermint/evm/v1/query.proto

@@ -86,6 +86,11 @@ service Query {
   rpc CreateAccessList(EthCallRequest) returns (CreateAccessListResponse) {
     option (google.api.http).get = "/ethermint/evm/v1/create_access_list";
   }
+
+  // SimulateV1 implements the `eth_simulateV1` rpc api
+  rpc SimulateV1(SimulateV1Request) returns (SimulateV1Response) {
+    option (google.api.http).post = "/ethermint/evm/v1/simulate_v1";
+  }
 }
 
 // QueryAccountRequest is the request type for the Query/Account RPC method.
@@ -365,4 +370,26 @@ message QueryBaseFeeResponse {
 message CreateAccessListResponse {
   // data is the response serialized in bytes
   bytes data = 1;
-}
+}
+
+// SimulateV1Request defines the request for eth_simulateV1
+message SimulateV1Request {
+  // args is the JSON-encoded rpc/types.SimulateV1Args (SimOpts plus resolved base header)
+  bytes args = 1;
+  // gas_cap defines the default gas cap to be used
+  uint64 gas_cap = 2;
+  // proposer_address of the requested block in hex format
+  bytes proposer_address = 3 [(gogoproto.casttype) = "github.com/cosmos/cosmos-sdk/types.ConsAddress"];
+  // chain_id is the eip155 chain id parsed from the requested block header
+  int64 chain_id = 4;
+}
+
+// SimulateV1Response defines the response for eth_simulateV1
+message SimulateV1Response {
+  // result is the JSON-encoded simulation results (set on success, empty on error)
+  bytes result = 1;
+  // error_message is a human-readable description of the simulation error (empty on success)
+  string error_message = 2;
+  // error_code is the machine-readable simulation error code (0 on success)
+  int32 error_code = 3;
+}

rpc/backend/backend.go

@@ -148,6 +148,9 @@ type EVMBackend interface {
 	TraceTransaction(hash common.Hash, config *rpctypes.TraceConfig) (interface{}, error)
 	TraceBlock(height rpctypes.BlockNumber, config *rpctypes.TraceConfig, block *tmrpctypes.ResultBlock) ([]*evmtypes.TxTraceResult, error)
 	TraceCall(args evmtypes.TransactionArgs, blockNr rpctypes.BlockNumberOrHash, config *rpctypes.TraceConfig) (interface{}, error)
+
+	// Simulation
+	SimulateV1(opts rpctypes.SimOpts, blockNr rpctypes.BlockNumber) (json.RawMessage, error)
 }
 
 var _ BackendI = (*Backend)(nil)

rpc/backend/call_tx.go

@@ -423,7 +423,7 @@ func (b *Backend) DoCall(
 	}
 	length := len(res.Ret)
 	if length > int(b.cfg.JSONRPC.ReturnDataLimit) && b.cfg.JSONRPC.ReturnDataLimit != 0 {
-		return nil, fmt.Errorf("call retuned result on length %d exceeding limit %d", length, b.cfg.JSONRPC.ReturnDataLimit)
+		return nil, fmt.Errorf("call returned result of length %d exceeding limit %d", length, b.cfg.JSONRPC.ReturnDataLimit)
 	}
 
 	if err = b.handleRevertError(res.VmError, res.Ret); err != nil {