litesvm, mollusk & solana-bankrun

Fast Solana program testing avoids full solana-test-validator round-trips. LiteSVM 0.6.x runs an in-process SVM for Rust tests. Mollusk executes single instructions against program ELF with fixtures. solana-bankrun (Bankrun) embeds a validator-like environment for TypeScript integration tests. Pick based on language and fidelity needs on Agave 4.1.1 semantics.

Recipe

Quick-reference recipe card - copy-paste ready.

[dev-dependencies]
litesvm = "0.6"
mollusk-svm = "0.1"

npm install -D solana-bankrun @solana/kit@7.0.0

use litesvm::LiteSVM;
 
let mut svm = LiteSVM::new();
// svm.add_program(...) and send txs in tests

When to reach for this:

• Unit tests for Anchor/native programs in CI without Docker validators.
• Benchmarking CU usage across instruction variants.
• TS integration tests that load your .so and assert account deltas.
• Rapid red/green loops during security fixes.

Working Example

use litesvm::LiteSVM;
use solana_sdk::{
    instruction::{AccountMeta, Instruction},
    pubkey::Pubkey,
    signature::{Keypair, Signer},
    system_program,
    transaction::Transaction,
};
 
#[test]
fn transfer_in_litesvm() {
    let mut svm = LiteSVM::new();
    let payer = Keypair::new();
    let recipient = Keypair::new();
 
    svm.airdrop(&payer.pubkey(), 1_000_000_000).unwrap();
 
    let ix = Instruction {
        program_id: system_program::ID,
        accounts: vec![
            AccountMeta::new(payer.pubkey(), true),
            AccountMeta::new(recipient.pubkey(), false),
        ],
        data: solana_sdk::system_instruction::transfer(&payer.pubkey(), &recipient.pubkey(), 10_000).data,
    };
 
    let bh = svm.latest_blockhash();
    let tx = Transaction::new_signed_with_payer(&[ix], Some(&payer.pubkey()), &[&payer], bh);
    svm.send_transaction(tx).unwrap();
 
    let bal = svm.get_balance(&recipient.pubkey()).unwrap();
    assert_eq!(bal, 10_000);
}

What this demonstrates:

• LiteSVM airdrops lamports without CLI faucet.
• Real system program instruction executes in-process.
• Blockhash comes from svm state, not external RPC.
• Assertions read balances directly from svm.

Deep Dive

How It Works

• LiteSVM embeds Agave-compatible execution for loaded program binaries.
• Mollusk focuses on single-instruction harness with mocked accounts list.
• Bankrun spins bank state for TS tests with program deploy hooks.
• None replace full validator tests for RPC/network edge cases entirely.

Rust Crate Table

TypeScript / NPM Table

Rust Notes

// Load your program .so in LiteSVM tests
// svm.add_program(program_id, "target/deploy/my_program.so");
 
// Compare CU logs with `mollusk` for hot instruction tuning

Gotchas

• Testing without deployed BPF artifact - empty program id failures. Fix: anchor build before tests; wire path in CI.
• Feature drift from mainnet - syscall availability differs by version. Fix: pin LiteSVM 0.6.x with Agave 4.1.1 toolchain.
• Bankrun program path wrong in monorepos - stale .so. Fix: copy artifact in test setup script.
• Over-mocking accounts in Mollusk - passes tests, fails mainnet. Fix: add LiteSVM integration cases.
• Skipping validator tests entirely - miss RPC serialization bugs. Fix: keep a thin solana-test-validator suite.

Alternatives

FAQs

Related

• LiteSVM - detailed guide
• Mollusk - instruction harness
• Bankrun (TS) - TS tests
• Testing Basics - pyramid

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.