test_top_frame_new_account_skipped_for_nonce_only_recipient()

Documentation for tests/amsterdam/eip2780_reduce_intrinsic_tx_gas/test_top_frame_charges.py::test_top_frame_new_account_skipped_for_nonce_only_recipient@2119b382.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip2780_reduce_intrinsic_tx_gas/test_top_frame_charges.py::test_top_frame_new_account_skipped_for_nonce_only_recipient --fork Amsterdam

A recipient that is alive only by its nonce (nonce=1, zero balance, no code) is not empty per EIP-161, so a value transfer to it does not incur the top-frame NEW_ACCOUNT charge. This pins that the gate keys on is_account_alive, not balance == 0.

Such an account is reachable on-chain: any EOA that has sent a transaction (nonce bumped) and been fully drained sits at nonce>0, balance=0, no code.

The gas limit is pinned to exactly the intrinsic, leaving no room for any extra charge: an implementation that wrongly charged NEW_ACCOUNT (keying on the zero balance) would out-of-gas rather than succeed. The recipient has no code, so no EVM runs and the intrinsic is fully consumed with nothing to refund.

Source code in tests/amsterdam/eip2780_reduce_intrinsic_tx_gas/test_top_frame_charges.py

@pytest.mark.pre_alloc_mutable
def test_top_frame_new_account_skipped_for_nonce_only_recipient(
    fork: Fork,
    pre: Alloc,
    state_test: StateTestFiller,
) -> None:
    """
    A recipient that is alive only by its nonce (``nonce=1``, zero
    balance, no code) is not empty per EIP-161, so a value transfer to
    it does *not* incur the top-frame ``NEW_ACCOUNT`` charge. This pins
    that the gate keys on ``is_account_alive``, not ``balance == 0``.

    Such an account is reachable on-chain: any EOA that has sent a
    transaction (nonce bumped) and been fully drained sits at
    ``nonce>0, balance=0, no code``.

    The gas limit is pinned to exactly the intrinsic, leaving no room
    for any extra charge: an implementation that wrongly charged
    ``NEW_ACCOUNT`` (keying on the zero balance) would out-of-gas
    rather than succeed. The recipient has no code, so no EVM runs and
    the intrinsic is fully consumed with nothing to refund.
    """
    sender_initial_balance = 10**18
    sender = pre.fund_eoa(sender_initial_balance)
    # Alive via nonce only: not empty per EIP-161 because nonce != 0.
    target = pre.fund_eoa(amount=0, nonce=1)
    value = 1

    intrinsic_gas = fork.transaction_intrinsic_cost_calculator()(
        sends_value=True,
        recipient_type=RecipientType.EOA,
        return_cost_deducted_prior_execution=True,
    )
    top_frame_state_gas = fork.transaction_top_frame_state_gas(
        sends_value=True,
        recipient_type=RecipientType.EOA,
    )
    assert top_frame_state_gas == 0, (
        "a nonce-only-alive recipient must not incur the NEW_ACCOUNT charge"
    )

    gas_price = 1_000_000_000
    gas_limit = intrinsic_gas
    tx = Transaction(
        sender=sender,
        to=target,
        value=value,
        gas_limit=gas_limit,
        gas_price=gas_price,
    )

    sender_final_balance = (
        sender_initial_balance - value - intrinsic_gas * gas_price
    )
    post = {
        sender: Account(nonce=1, balance=sender_final_balance),
        target: Account(nonce=1, balance=value),
    }

    state_test(pre=pre, tx=tx, post=post)

Parametrized Test Cases

This test generates 1 parametrized test case across 1 fork.