test_cross_frame_credit_returns_at_settlement()

Documentation for tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_cross_frame_refund.py::test_cross_frame_credit_returns_at_settlement@622620d8.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_cross_frame_refund.py::test_cross_frame_credit_returns_at_settlement --fork Amsterdam

Test the cross-frame credit refunds the sender at settlement.

The frame's spilled set is cleared by a child and the merge repays the credit. Settlement sums gas_left and the reservoir, so the spilled charge and the credit cancel wherever the credit sits and the receipt carries no state term at all.

Source code in tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_cross_frame_refund.py

@pytest.mark.valid_from("EIP8037")
def test_cross_frame_credit_returns_at_settlement(
    state_test: StateTestFiller,
    pre: Alloc,
    fork: Fork,
) -> None:
    """
    Test the cross-frame credit refunds the sender at settlement.

    The frame's spilled set is cleared by a child and the merge repays
    the credit. Settlement sums `gas_left` and the reservoir, so the
    spilled charge and the credit cancel wherever the credit sits and
    the receipt carries no state term at all.
    """
    intrinsic_cost = fork.transaction_intrinsic_cost_calculator()()
    sstore_state_gas = Op.SSTORE(new_value=1).state_cost(fork)

    clearer_code = WARM_CLEAR(SLOT_X, 0)
    clearer = pre.deploy_contract(code=clearer_code)

    # A budget covering the child's SSTORE stipend sentry through the
    # clear, so the child succeeds and returns the sentry unspent.
    child_budget = budget_above_sstore_stipend(fork, clearer_code)
    code = Op.SSTORE(
        SLOT_X,
        1,
        key_warm=False,
        original_value=0,
        current_value=0,
        new_value=1,
    ) + Op.POP(
        Op.DELEGATECALL(gas=child_budget, address=clearer, address_warm=False)
    )
    contract = pre.deploy_contract(code=code)

    before_refund = (
        intrinsic_cost
        + code.execution_cost(fork)
        + clearer_code.execution_cost(fork)
    )
    # Clearing the slot back to its original value also refunds the
    # write cost through the classic refund counter at settlement.
    restore_refund = clearer_code.refund(fork) - sstore_state_gas
    expected_gas_used = before_refund - min(
        before_refund // fork.max_refund_quotient(), restore_refund
    )
    # The post-refund usage must clear the calldata floor, or the
    # floor masks a lost or doubled credit.
    assert expected_gas_used > fork.transaction_data_floor_cost_calculator()(
        data=b""
    )

    tx = Transaction(
        to=contract,
        state_gas_reservoir=0,
        sender=pre.fund_eoa(),
        expected_receipt=TransactionReceipt(
            cumulative_gas_used=expected_gas_used
        ),
    )

    post = {contract: Account(storage={SLOT_X: 0})}
    state_test(pre=pre, post=post, tx=tx)

Parametrized Test Cases

This test generates 1 parametrized test case across 1 fork.