We should add unit tests to make sure that the follwing procedures/functions implemented in MASM and Rust are equivalent:

• kernel::asset_vault::build_fungible_asset_vault_key and FungibleAsset::vault_key
• kernel::asset_vault::build_non_fungible_asset_vault_key and NonFungibleAsset::vault_key

These could look similar to test_is_faucet_procedure or test_account_type.

A larger question is whether we should come up with a small unit test framework that makes writing such tests very convenient, since we should be testing probably all such functionality that is implemented in MASM and Rust (e.g. every procedure in crates/miden-lib/asm/{shared_modules, shared_utils}). That could also simplify the above-mentioned tests to avoid reimplementing the same setup every time.

For example, a rough API could just setup the input, expected output and the MASM code under test, e.g.:

// Test cases consisting of (input, expected_output) tuples.
let test_cases = [
    ACCOUNT_ID_REGULAR_PUBLIC_ACCOUNT_IMMUTABLE_CODE,
    ACCOUNT_ID_REGULAR_PRIVATE_ACCOUNT_UPDATABLE_CODE,
    ACCOUNT_ID_PUBLIC_FUNGIBLE_FAUCET,
    ACCOUNT_ID_PRIVATE_NON_FUNGIBLE_FAUCET,
]
.map(|id| {
    let id = AccountId::try_from(id).unwrap();
    (id.prefix().as_felt(), id.is_faucet())
});

let code = "
  use.kernel::account_id

  begin
      exec.account_id::is_faucet
      # => [is_faucet, account_id_prefix]

      # truncate the stack
      swap drop
  end";

// This would place the account ID on the stack, and assert that the stack output from MASM matches the expected output passed in test cases.
MasmUnitTests::execute(code, test_cases)?;

The exact API needs to be figured out. If it is more convenient to add test cases in builder-style, then we should do that instead or offer alternatives.

So I would say the task here is to:

• Investigate if there are enough procedures/functions that are shared across MASM and Rust that could be tested in this way (stateless functions).
  • If so, add a unit test framework as above and rewrite the mentioned tests to use it.
  • If not, add tests for the vault key procedures.