test_child_clear_window_cost()

Documentation for tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_cross_frame_refund.py::test_child_clear_window_cost@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_child_clear_window_cost --fork Amsterdam

Test a successful clearing child repays a parent spill at the merge.

The same shape as test_child_clear_repays_own_spill_first, with the call bracketed by two GAS reads. A successful child repays one parent spill, so its window costs one state charge less than the call and child execution. A failing child repays nothing. What the sender pays is checked there.

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

@pytest.mark.parametrize("child_ending", ["stop", "revert", "invalid"])
@pytest.mark.valid_from("EIP8037")
def test_child_clear_window_cost(
    state_test: StateTestFiller,
    pre: Alloc,
    fork: Fork,
    child_ending: str,
) -> None:
    """
    Test a successful clearing child repays a parent spill at the merge.

    The same shape as `test_child_clear_repays_own_spill_first`, with
    the call bracketed by two `GAS` reads. A successful child repays one
    parent spill, so its window costs one state charge less than the
    call and child execution. A failing child repays nothing. What the
    sender pays is checked there.
    """
    sstore_state_gas = Op.SSTORE(new_value=1).state_cost(fork)

    child_code = clearing_child_code(child_ending)
    child = pre.deploy_contract(code=child_code)
    child_budget = budget_above_sstore_stipend(fork, child_code)

    call_window = Op.POP(
        Op.DELEGATECALL(gas=child_budget, address=child, address_warm=False)
    )
    code = (
        FRESH_SET(SLOT_X, 1)
        + FRESH_SET(SLOT_Y, 1)
        + Op.MSTORE(32, 0, new_memory_size=64, old_memory_size=0)
        + Op.MSTORE(0, Op.GAS)
        + call_window
        + Op.MSTORE(32, Op.GAS)
        + FRESH_SET(SLOT_RESULT, Op.SUB(Op.MLOAD(0), Op.MLOAD(32)))
    )
    contract = pre.deploy_contract(code=code)

    # An invalid child burns its whole budget; the others stop at the
    # end of their code.
    child_consumed = (
        child_budget
        if child_ending == "invalid"
        else child_code.execution_cost(fork)
    )
    # Gas measured between the two reads: the first stamp's store, the
    # call window, the child's consumption, and the second read itself.
    window_cost = (
        Op.MSTORE(0, Op.GAS).gas_cost(fork)
        + call_window.execution_cost(fork)
        + child_consumed
    )

    tx = Transaction(
        to=contract,
        state_gas_reservoir=0,
        sender=pre.fund_eoa(),
    )

    repaid = sstore_state_gas if child_ending == "stop" else 0
    post = {
        contract: Account(
            storage={
                **clearing_child_storage(child_ending),
                SLOT_RESULT: window_cost - repaid,
            }
        )
    }
    state_test(pre=pre, post=post, tx=tx)

Parametrized Test Cases

This test generates 3 parametrized test cases across 1 fork.