ethclient/gethclient: this change modifies the gethclient to properly…

… override the state for the Code property

If the code property is not present in the state overrides, it should be skipped or set to null on marshal. Because of the type of the property hexutil.Bytes the empty slice marshals to 0x and the request fails.

fixes ethereum#25615

ethclient/gethclient/gethclient.go

@@ -216,16 +216,24 @@ func toOverrideMap(overrides *map[common.Address]OverrideAccount) interface{} {
 	}
 	type overrideAccount struct {
 		Nonce     hexutil.Uint64              `json:"nonce"`
-		Code      hexutil.Bytes               `json:"code"`
+		Code      []byte                      `json:"code"`
 		Balance   *hexutil.Big                `json:"balance"`
 		State     map[common.Hash]common.Hash `json:"state"`
 		StateDiff map[common.Hash]common.Hash `json:"stateDiff"`
 	}
 	result := make(map[common.Address]overrideAccount)
+
 	for addr, override := range *overrides {
+		var code []byte
+
+		if len(override.Code) > 0 {
+			// convert to hexutil.Bytes explicitly in order to marshal/unmarshal as a JSON string with 0x prefix.
+			code = hexutil.Bytes(override.Code)
+		}
+
 		result[addr] = overrideAccount{
 			Nonce:     hexutil.Uint64(override.Nonce),
-			Code:      override.Code,
+			Code:      code,
 			Balance:   (*hexutil.Big)(override.Balance),
 			State:     override.State,
 			StateDiff: override.StateDiff,

ethclient/gethclient/gethclient_test.go

@@ -19,11 +19,13 @@ package gethclient
 import (
 	"bytes"
 	"context"
+	"encoding/json"
 	"math/big"
 	"testing"
 
 	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/rawdb"
@@ -135,6 +137,12 @@ func TestGethClient(t *testing.T) {
 		}, {
 			"TestCallContract",
 			func(t *testing.T) { testCallContract(t, client) },
+		}, {
+			"testCodeOverride",
+			func(t *testing.T) { testCodeOverride(t) },
+		}, {
+			"testNoCodeOverride",
+			func(t *testing.T) { testNoCodeOverride(t) },
 		},
 	}
 	t.Parallel()
@@ -327,3 +335,78 @@ func testCallContract(t *testing.T, client *rpc.Client) {
 		t.Fatalf("unexpected error: %v", err)
 	}
 }
+
+func testNoCodeOverride(t *testing.T) {
+	override := OverrideAccount{}
+
+	mapAcc := make(map[common.Address]OverrideAccount)
+	mapAcc[testAddr] = override
+
+	encoded := toOverrideMap(&mapAcc)
+
+	type overrideAccount struct {
+		Nonce     hexutil.Uint64              `json:"nonce"`
+		Code      []byte                      `json:"code"`
+		Balance   *hexutil.Big                `json:"balance"`
+		State     map[common.Hash]common.Hash `json:"state"`
+		StateDiff map[common.Hash]common.Hash `json:"stateDiff"`
+	}
+
+	var accounts map[common.Address]*overrideAccount
+	marshalled, err := json.Marshal(encoded)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	err = json.Unmarshal(marshalled, &accounts)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	account := accounts[testAddr]
+	if account == nil {
+		t.Fatal("unexpected error")
+	}
+
+	if account.Code != nil {
+		t.Fatal("unexpected error")
+	}
+}
+
+func testCodeOverride(t *testing.T) {
+	override := OverrideAccount{}
+	override.Code = []byte{1}
+
+	mapAcc := make(map[common.Address]OverrideAccount)
+	mapAcc[testAddr] = override
+
+	encoded := toOverrideMap(&mapAcc)
+
+	type overrideAccount struct {
+		Nonce     hexutil.Uint64              `json:"nonce"`
+		Code      []byte                      `json:"code"`
+		Balance   *hexutil.Big                `json:"balance"`
+		State     map[common.Hash]common.Hash `json:"state"`
+		StateDiff map[common.Hash]common.Hash `json:"stateDiff"`
+	}
+
+	var accounts map[common.Address]*overrideAccount
+	marshalled, err := json.Marshal(encoded)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	err = json.Unmarshal(marshalled, &accounts)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	account := accounts[testAddr]
+	if account == nil {
+		t.Fatal("unexpected error")
+	}
+
+	if account.Code == nil {
+		t.Fatal("unexpected error")
+	}
+}