Mollusk 0.17: unit-test a Solana instruction without a validator

Mollusk is Anza's lightweight test harness for Solana programs. It runs an instruction through a minified SVM: program cache, transaction context, invoke context, BPF Loader. It does not stand up a validator. Repo anza-xyz/mollusk. Crate mollusk-svm. X @anza_xyz.

You pass the instruction and an explicit account list. There is no AccountsDB or Bank to load from. process_instruction returns the result. process_and_validate_instruction then applies Checks: success, lamports, and Check::compute_units. Chains and MolluskContext cover multi-instruction tests. 0.17.0 shipped 4 Nov 2026. 0.17.1 (5 Nov) fixes the CU budget. A separate tag tracks Agave 4.5 alpha.

Next to LiteSVM: LiteSVM is an in-process VM for full transactions. Mollusk is an instruction harness. Pick Mollusk when the unit is one instruction and CU assertions. Apache-2.0. LinkedIn company/anza-xyz.