Bankrun

# Bankrun

Bankrun is a superfast, powerful and lightweight framework for testing Solana programs in NodeJS.

While people often use solana-test-validator for this, bankrun is orders of magnitude faster and far more convenient.

You can also do things that are not possible with solana-test-validator, such as jumping back and forth in time or dynamically setting account data.

If you've used solana-program-test (opens new window) you'll be familiar with bankrun, since that's what it uses under the hood.

For those unfamiliar, bankrun and solana-program-test work by spinning up a lightweight BanksServer that's like an RPC node but much faster, and creating a BanksClient to talk to the server. This author thought solana-program-test was a boring name, so he chose bankrun instead (you're running Solana Banks (opens new window)).

# Minimal example

This example just transfers lamports from Alice to Bob without loading any programs of our own. It uses the jest (opens new window) test runner but you can use any test runner you like.

Note: If you have multiple test files you should disable parallel tests using the --runInBand Jest flag for now. There is an open issue (opens new window) where concurrent Jest tests occasionally fail due to the program name getting garbled.

Note: The underlying Rust process may print a lot of logs. You can control these with the RUST_LOG environment variable. If you want to silence these logs your test command would look like RUST_LOG= jest --runInBand.

import { start } from "solana-bankrun";
import { PublicKey, Transaction, SystemProgram } from "@solana/web3.js";

test("one transfer", async () => {
	const context = await start([], []);
	const client = context.banksClient;
	const payer = context.payer;
	const receiver = PublicKey.unique();
	const blockhash = context.lastBlockhash;
	const transferLamports = 1_000_000n;
	const ixs = [
		SystemProgram.transfer({
			fromPubkey: payer.publicKey,
			toPubkey: receiver,
			lamports: transferLamports,
		}),
	];
	const tx = new Transaction();
	tx.recentBlockhash = blockhash;
	tx.add(...ixs);
	tx.sign(payer);
	await client.processTransaction(tx);
	const balanceAfter = await client.getBalance(receiver);
	expect(balanceAfter).toEqual(transferLamports);
});

Some things to note here:

  • The context object contains a banks_client to talk to the BanksServer, a payer keypair that has been funded with a bunch of SOL, and a last_blockhash that we can use in our transactions.
  • We haven't loaded any specific programs, but by default we have access to the System Program, the SPL token programs and the SPL memo program.

# Installation

yarn add solana-bankrun

# Contributing

Make sure you have Yarn and the Rust toolchain installed.

Then run yarn to install deps, run yarn build to build the binary and yarn test to run the tests.

Tutorial →