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test_value_moving_transactions()

Documentation for tests/amsterdam/eip2780_reduce_intrinsic_tx_gas/test_value_moving_transactions.py::test_value_moving_transactions@87aba1a3.

Generate fixtures for these test cases for Amsterdam with:

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

Ensure value-moving transactions charge gas correctly across every non-create recipient type.

Self-transfers are carved out: the sender pays only the recipient -access-free intrinsic and the value is moved to itself, so the sender's post-tx balance reflects only gas. Pre-existing 7702 delegations on the recipient surface as an extra top-frame COLD_ACCOUNT_ACCESS; empty recipients trigger the top-frame NEW_ACCOUNT state charge when value is transferred.

The EIP-7708 transfer log is asserted to fire exactly when TRANSFER_LOG_COST is charged: for a non-self value transfer, and never for a self-transfer (carve-out) or a zero-value tx.

Source code in tests/amsterdam/eip2780_reduce_intrinsic_tx_gas/test_value_moving_transactions.py 
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@pytest.mark.parametrize("recipient_type", RECIPIENT_TYPES_NON_CREATE)
@pytest.mark.parametrize(
    "value",
    [
        pytest.param(0, id="zero_value"),
        pytest.param(1, id="non-zero_value"),
    ],
)
def test_value_moving_transactions(
    fork: Fork,
    pre: Alloc,
    state_test: StateTestFiller,
    recipient_type: RecipientType,
    value: int,
) -> None:
    """
    Ensure value-moving transactions charge gas correctly across every
    non-create recipient type.

    Self-transfers are carved out: the sender pays only the recipient
    -access-free intrinsic and the value is moved to itself, so the
    sender's post-tx balance reflects only gas. Pre-existing 7702
    delegations on the recipient surface as an extra top-frame
    ``COLD_ACCOUNT_ACCESS``; empty recipients trigger the top-frame
    ``NEW_ACCOUNT`` state charge when value is transferred.

    The EIP-7708 transfer log is asserted to fire exactly when
    ``TRANSFER_LOG_COST`` is charged: for a non-self value transfer,
    and never for a self-transfer (carve-out) or a zero-value tx.
    """
    sender_initial_balance = 10**18
    sender = pre.fund_eoa(sender_initial_balance)
    target = setup_target(pre, recipient_type, sender)

    target_initial_balance = (
        EOA_INITIAL_BALANCE if recipient_type == RecipientType.EOA else 0
    )

    intrinsic_gas = fork.transaction_intrinsic_cost_calculator()(
        sends_value=bool(value),
        recipient_type=recipient_type,
        return_cost_deducted_prior_execution=True,
    )
    top_frame_gas = fork.transaction_top_frame_gas_calculator()(
        sends_value=bool(value),
        recipient_type=recipient_type,
    )
    top_frame_state_gas = fork.transaction_top_frame_state_gas(
        sends_value=bool(value),
        recipient_type=recipient_type,
    )
    # Under the default zero state-gas reservoir, top-frame state gas
    # spills entirely into regular gas.
    total_gas_cost = intrinsic_gas + top_frame_gas + top_frame_state_gas

    tx_gas_limit = total_gas_cost + 1000  # add a small buffer
    gas_price = 1_000_000_000

    is_self_transfer = recipient_type == RecipientType.SELF

    # A transfer log is emitted iff value moves to a distinct account,
    # which is exactly when the intrinsic includes ``TRANSFER_LOG_COST``.
    # ``logs=[]`` asserts no log fires for the carved-out cases.
    if value > 0 and not is_self_transfer:
        expected_logs = [transfer_log(sender, target, value)]
    else:
        expected_logs = []

    tx = Transaction(
        sender=sender,
        to=target,
        value=value,
        gas_limit=tx_gas_limit,
        gas_price=gas_price,
        expected_receipt=TransactionReceipt(logs=expected_logs),
    )

    sender_value_delta = 0 if is_self_transfer else value
    sender_final_balance = (
        sender_initial_balance
        - sender_value_delta
        - total_gas_cost * gas_price
    )

    post: dict[Address, Account | None] = {
        sender: Account(nonce=1, balance=sender_final_balance),
    }
    if not is_self_transfer:
        if recipient_type == RecipientType.EMPTY_ACCOUNT and value == 0:
            post[target] = None
        else:
            post[target] = Account(balance=target_initial_balance + value)

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

Parametrized Test Cases

This test generates 10 parametrized test cases across 1 fork.