test_cross_frame_refund_repays_spill_at_merge()

Documentation for tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_cross_frame_refund.py::test_cross_frame_refund_repays_spill_at_merge@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_refund_repays_spill_at_merge --fork Amsterdam

Test a cross-frame refund repays the spill when the child merges.

The frame sets a slot with an empty or half-slot reservoir, spilling the uncovered state charge from gas_left. A child sharing the caller's storage clears the slot and the credit lands in the reservoir, which repays the spill on the merge: gas_left is higher after the clearing call than before it, and the clearing window costs exactly the spilled amount less than a no-op window. Half-slot funding makes the spill smaller than the full-slot refund, catching repayment tracked by slot count.

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

@pytest.mark.parametrize("call_opcode", [Op.CALLCODE, Op.DELEGATECALL])
@pytest.mark.parametrize(
    "fund_half_slot",
    [False, True],
    ids=["empty-reservoir", "half-slot-reservoir"],
)
@pytest.mark.valid_from("EIP8037")
def test_cross_frame_refund_repays_spill_at_merge(
    state_test: StateTestFiller,
    pre: Alloc,
    call_opcode: Opcode,
    fork: Fork,
    fund_half_slot: bool,
) -> None:
    """
    Test a cross-frame refund repays the spill when the child merges.

    The frame sets a slot with an empty or half-slot reservoir, spilling
    the uncovered state charge from `gas_left`. A child sharing the
    caller's storage clears the slot and the credit lands in the
    reservoir, which repays the spill on the merge:
    `gas_left` is higher after the clearing call than before it, and
    the clearing window costs exactly the spilled amount less than a
    no-op window. Half-slot funding makes the spill smaller than the
    full-slot refund, catching repayment tracked by slot count.
    """
    sstore_state_gas = Op.SSTORE(new_value=1).state_cost(fork)
    reservoir = sstore_state_gas // 2 if fund_half_slot else 0
    spilled = sstore_state_gas - reservoir

    clearer = pre.deploy_contract(code=Op.SSTORE(SLOT_X, 0))
    window = Op.POP(call_opcode(address=clearer))
    contract = pre.deploy_contract(
        code=clearing_probe_code(Op.SSTORE(SLOT_X, 1), [window] * 3)
    )

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

    post = {
        contract: Account(
            storage={
                SLOT_X: 0,
                SLOT_MARKER: 1,
                SLOT_INCREASED: 1,
                SLOT_RESULT: -spilled,
            }
        )
    }
    state_test(pre=pre, post=post, tx=tx)

Parametrized Test Cases

This test generates 4 parametrized test cases across 1 fork.