Merge pull request #17 from solana-developers/add-confirmtransaction

Add confirmTransaction()

README.md

@@ -16,6 +16,8 @@ Eventually most of these will end up in `@solana/web3.js`.
 
 [Get a Solana Explorer link for a transaction, address, or block](#getexplorerlinktype-identifier-clustername)
 
+[Confirm a transaction (includes getting a recent blockhash)](#confirmTransaction)
+
 [Get a keypair from a keypair file (like id.json)](#getkeypairfromfilefilename)
 
 [Get a keypair from an environment variable](#getkeypairfromenvironmentenvironmentvariable)
@@ -155,6 +157,14 @@ getExplorerLink("block", "241889720", "mainnet-beta");
 
 Will return `"https://explorer.solana.com/block/241889720"`
 
+### confirmTransaction(connection, transaction)
+
+Confirm a transaction, and also gets the recent blockhash required to confirm it.
+
+```typescript
+await confirmTransaction(connection, transaction);
+```
+
 ## node.js specific helpers
 
 ### getKeypairFromFile(filename)

src/index.test.ts

@@ -7,9 +7,16 @@ import {
   requestAndConfirmAirdrop,
   requestAndConfirmAirdropIfRequired,
   getExplorerLink,
+  confirmTransaction,
   makeKeypairs,
 } from "./index";
-import { Connection, Keypair, LAMPORTS_PER_SOL } from "@solana/web3.js";
+import {
+  Connection,
+  Keypair,
+  LAMPORTS_PER_SOL,
+  SystemProgram,
+  Transaction,
+} from "@solana/web3.js";
 import assert from "node:assert/strict";
 import base58 from "bs58";
 // See https://m.media-amazon.com/images/I/51TJeGHxyTL._SY445_SX342_.jpg
@@ -288,6 +295,32 @@ describe("getExplorerLink", () => {
   });
 });
 
+describe.only("confirmTransaction", () => {
+  test("confirmTransaction works for a successful transaction", async () => {
+    const connection = new Connection(LOCALHOST);
+    const [sender, recipient] = [Keypair.generate(), Keypair.generate()];
+    const lamportsToAirdrop = 2 * LAMPORTS_PER_SOL;
+    await requestAndConfirmAirdrop(
+      connection,
+      sender.publicKey,
+      lamportsToAirdrop,
+    );
+
+    const transaction = await connection.sendTransaction(
+      new Transaction().add(
+        SystemProgram.transfer({
+          fromPubkey: sender.publicKey,
+          toPubkey: recipient.publicKey,
+          lamports: 1_000_000,
+        }),
+      ),
+      [sender],
+    );
+
+    await confirmTransaction(connection, transaction);
+  });
+});
+
 describe("makeKeypairs", () => {
   test("makeKeypairs() creates the correct number of keypairs", () => {
     const keypairs = makeKeypairs(3);

src/index.ts

@@ -165,9 +165,9 @@ export const requestAndConfirmAirdrop = async (
       lastValidBlockHeight: latestBlockHash.lastValidBlockHeight,
       signature: airdropTransactionSignature,
     },
-    "confirmed",
+    "finalized",
   );
-  return connection.getBalance(publicKey, "confirmed");
+  return connection.getBalance(publicKey, "finalized");
 };
 
 export const requestAndConfirmAirdropIfRequired = async (
@@ -183,6 +183,27 @@ export const requestAndConfirmAirdropIfRequired = async (
   return balance;
 };
 
+export const confirmTransaction = async (
+  connection: Connection,
+  signature: string,
+): Promise<string> => {
+  const block = await connection.getLatestBlockhash();
+  const res = await connection.confirmTransaction({
+    signature,
+    ...block,
+  });
+
+  /**
+   * note: `confirmTransaction` does not throw an error if the confirmation does not succeed,
+   * but rather a `TransactionError` object. so we handle that here
+   *
+   * https://solana-labs.github.io/solana-web3.js/classes/Connection.html#confirmTransaction.confirmTransaction-1
+   */
+  if (!!res.value.err) throw Error(res.value.err.toString());
+
+  return signature;
+};
+
 // Shout out to deanmlittle for this technique
 export const makeKeypairs = (amount: number): Array<Keypair> => {
   return Array.from({ length: amount }, () => Keypair.generate());