refactor: Use Account.IsContract() in statedb instead of manual check…

…, add IsContract tests

x/evm/statedb/account_test.go

@@ -62,3 +62,40 @@ func TestAccountIsEmpty(t *testing.T) {
 		})
 	}
 }
+
+func TestAccountIsContract(t *testing.T) {
+	tests := []struct {
+		name     string
+		account  statedb.Account
+		expected bool
+	}{
+		{
+			name: "Empty account",
+			account: statedb.Account{
+				Balance:  big.NewInt(0),
+				Nonce:    0,
+				CodeHash: emptyCodeHash,
+			},
+			expected: false,
+		},
+		{
+			name: "Non-empty code hash",
+			account: statedb.Account{
+				Balance:  big.NewInt(0),
+				Nonce:    0,
+				CodeHash: []byte{1, 2, 3},
+			},
+			expected: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.Equal(
+				t,
+				tt.expected,
+				tt.account.IsContract(),
+			)
+		})
+	}
+}

x/evm/statedb/statedb.go

@@ -16,7 +16,6 @@
 package statedb
 
 import (
-	"bytes"
 	"fmt"
 	"math/big"
 
@@ -112,6 +111,8 @@ func (s *StateDB) Empty(addr common.Address) bool {
 		return true
 	}
 
+	// This relies on the Account.CodeHash to be set correctly when the account
+	// code is set.
 	return account.IsEmpty()
 }
 
@@ -142,7 +143,8 @@ func (s *StateDB) GetCode(addr common.Address) []byte {
 		return nil
 	}
 
-	if bytes.Equal(account.CodeHash, emptyCodeHash) {
+	// If the account has an empty codehash, there is no code.
+	if !account.IsContract() {
 		return nil
 	}