fix: Legacy Transaction Simulation ComputeUnits

src/lib/transaction.ts

@@ -1,4 +1,14 @@
-import { AddressLookupTableAccount, Commitment, ComputeBudgetProgram, Connection, PublicKey, TransactionInstruction, TransactionMessage, VersionedTransaction } from "@solana/web3.js";
+import {
+  AddressLookupTableAccount,
+  Commitment,
+  ComputeBudgetProgram,
+  Connection,
+  PublicKey,
+  TransactionInstruction,
+  TransactionMessage,
+  VersionedTransaction,
+  Signer, Transaction
+} from "@solana/web3.js";
 import { getErrorFromRPCResponse } from "./logs";
 
 export const confirmTransaction = async (
@@ -54,4 +64,49 @@ export const getSimulationComputeUnits = async (
 
   getErrorFromRPCResponse(rpcResponse);
   return rpcResponse.value.unitsConsumed || null;
-};
+};
+
+export const getLegacySimulationComputeUnits = async (
+  connection: Connection,
+  instructions: Array<TransactionInstruction>,
+  signers: Array<PublicKey> | Array<Signer>,
+  feePayer?: PublicKey | Signer
+): Promise<number | null> => {
+  const testInstructions = [
+    // Set an arbitrarily high number in simulation
+    // so we can be sure the transaction will succeed
+    // and get the real compute units used
+    ComputeBudgetProgram.setComputeUnitLimit({units: 1_400_000}),
+    ...instructions,
+  ];
+  signers = (signers as Signer[]).map(signer => signer?.publicKey ? signer.publicKey : signer) as Array<PublicKey>
+  feePayer = ((feePayer as Signer)?.publicKey ? (feePayer as Signer).publicKey : feePayer || signers[0]) as PublicKey
+
+  const transaction = new Transaction();
+  transaction.instructions = testInstructions;
+  transaction.feePayer = feePayer;
+  transaction.recentBlockhash = '11111111111111111111111111111111';
+
+  // deprecated:
+  // transaction.setSigners(...signers.map(signer => signer.publicKey))
+  transaction.signatures = signers.map(publicKey => ({
+    signature: null,
+    publicKey
+  }))
+
+  const args = [
+    transaction.serialize({ verifySignatures: false }).toString('base64'),
+    {
+      encoding: 'base64',
+      replaceRecentBlockhash: true
+    }
+  ];
+
+  // deprecated:
+  // const rpcResponse = await connection.simulateTransaction(transaction, signers);
+  // @ts-ignore
+  const rpcResponse = (await connection._rpcRequest('simulateTransaction', args)).result
+
+  getErrorFromRPCResponse(rpcResponse);
+  return rpcResponse.value.unitsConsumed || null;
+};