test_sstore_restoration_charge_in_ancestor()

Documentation for tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_sstore.py::test_sstore_restoration_charge_in_ancestor@87aba1a3.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_sstore.py::test_sstore_restoration_charge_in_ancestor --fork Amsterdam

Verify 0 to x to 0 refund when the 0 to x charge is in the parent and x to 0 runs num_hops DELEGATECALL/CALLCODE frames below, each sharing storage with the parent.

Every intermediate frame has zero local state_gas_used, so the refund must propagate up the chain to the ancestor that charged the 0 to x. A probe SSTORE sized to OOG by 1 detects any loss.

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

@pytest.mark.parametrize(
    "num_hops",
    [
        pytest.param(1, id="single_hop"),
        pytest.param(2, id="two_hops"),
        pytest.param(3, id="three_hops"),
        pytest.param(10, id="ten_hops"),
    ],
)
@pytest.mark.with_all_call_opcodes(
    selector=lambda call_opcode: call_opcode in (Op.DELEGATECALL, Op.CALLCODE)
)
@pytest.mark.valid_from("EIP8037")
def test_sstore_restoration_charge_in_ancestor(
    state_test: StateTestFiller,
    pre: Alloc,
    fork: Fork,
    call_opcode: Op,
    num_hops: int,
) -> None:
    """
    Verify 0 to x to 0 refund when the 0 to x charge is in the parent
    and x to 0 runs `num_hops` DELEGATECALL/CALLCODE frames below,
    each sharing storage with the parent.

    Every intermediate frame has zero local `state_gas_used`, so the
    refund must propagate up the chain to the ancestor that charged
    the 0 to x.  A probe SSTORE sized to OOG by 1 detects any loss.
    """
    gas_costs = fork.gas_costs()
    sstore_state_gas = Op.SSTORE(new_value=1).state_cost(fork)
    probe_gas = (
        2 * gas_costs.VERY_LOW
        + gas_costs.COLD_STORAGE_WRITE
        + sstore_state_gas
        - 1
    )

    # Innermost frame does x to 0; each hop above delegates down.
    delegate_target = pre.deploy_contract(
        code=(
            Op.SSTORE.with_metadata(
                key_warm=True,
                original_value=0,
                current_value=1,
                new_value=0,
            )(0, 0)
            + Op.STOP
        )
    )
    for _ in range(num_hops - 1):
        delegate_target = pre.deploy_contract(
            code=Op.POP(call_opcode(gas=Op.GAS, address=delegate_target))
            + Op.STOP,
        )

    probe = pre.deploy_contract(code=Op.SSTORE(0, 1))

    parent_storage = Storage()
    parent_code = (
        Op.SSTORE(parent_storage.store_next(0, "cycle_restored"), 1)
        + Op.POP(call_opcode(gas=Op.GAS, address=delegate_target))
        + Op.SSTORE(
            parent_storage.store_next(1, "probe_must_succeed"),
            Op.CALL(gas=probe_gas, address=probe),
        )
    )
    parent = pre.deploy_contract(code=parent_code)

    # Reservoir starts at exactly sstore_state_gas; the parent's 0 to 1
    # drains it to zero before entering the delegation chain.
    tx = Transaction(
        sender=pre.fund_eoa(),
        to=parent,
        state_gas_reservoir=sstore_state_gas,
    )

    post = {parent: Account(storage=parent_storage)}
    state_test(pre=pre, tx=tx, post=post)

Parametrized Test Cases

This test generates 8 parametrized test cases across 1 fork.