test_create_collision_refunds_state_gas()

Documentation for tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_create.py::test_create_collision_refunds_state_gas@c74f1a67.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_create.py::test_create_collision_refunds_state_gas --fork Amsterdam

Verify CREATE/CREATE2 address collision refunds account state gas.

The collision path increments the factory nonce and burns the forwarded regular gas (consumed by the never-spawned child), but still refunds GAS_NEW_ACCOUNT to the reservoir. Tight gas tuning limits the factory's post-collision gas_left so the probe SSTORE can only succeed via the refunded reservoir, not by spilling state gas from gas_left.

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

@pytest.mark.pre_alloc_mutable()
@pytest.mark.with_all_create_opcodes()
@pytest.mark.valid_from("EIP8037")
def test_create_collision_refunds_state_gas(
    state_test: StateTestFiller,
    pre: Alloc,
    fork: Fork,
    create_opcode: Op,
) -> None:
    """
    Verify CREATE/CREATE2 address collision refunds account state gas.

    The collision path increments the factory nonce and burns the
    forwarded regular gas (consumed by the never-spawned child), but
    still refunds `GAS_NEW_ACCOUNT` to the reservoir. Tight gas
    tuning limits the factory's post-collision `gas_left` so the
    probe SSTORE can only succeed via the refunded reservoir, not
    by spilling state gas from `gas_left`.
    """
    gas_costs = fork.gas_costs()
    sstore_state_gas = Op.SSTORE(new_value=1).state_cost(fork)
    new_account_state_gas = gas_costs.NEW_ACCOUNT

    init_code = Op.STOP
    mstore_value, size = init_code_at_high_bytes(init_code)
    salt = 0

    storage = Storage()
    create_call = (
        create_opcode(value=0, offset=0, size=size, salt=salt)
        if create_opcode == Op.CREATE2
        else create_opcode(value=0, offset=0, size=size)
    )
    factory_code = (
        Op.MSTORE(0, mstore_value)
        + Op.POP(create_call)
        + Op.SSTORE(storage.store_next(1, "reservoir_ok"), 1)
    )
    factory = pre.deploy_contract(code=factory_code)

    collision_target = compute_create_address(
        address=factory,
        nonce=1,
        salt=salt,
        initcode=bytes(init_code),
        opcode=create_opcode,
    )
    pre.deploy_contract(code=Op.STOP, address=collision_target)

    # Tight gas tuning: factory retains
    # ~(forwarded - pre_sstore_regular) / 64 after collision burns
    # `max_message_call_gas` as regular. Target the discrimination
    # window `(probe_regular, probe_regular + sstore_state_gas)` so
    # the probe SSTORE regular fits but state gas spillover from
    # `gas_left` under the old behavior OOGs.
    pre_sstore_code = Op.MSTORE(0, mstore_value) + Op.POP(create_call)
    pre_sstore_regular = pre_sstore_code.gas_cost(fork) - new_account_state_gas
    probe_code = Op.SSTORE(0, 1)
    probe_regular = probe_code.gas_cost(fork) - sstore_state_gas
    target_gas_left = probe_regular + sstore_state_gas // 2
    forwarded_gas = target_gas_left * 64 + pre_sstore_regular
    # Reservoir sized for CREATE charge only — SSTORE must pull from
    # the refunded reservoir, not from spill.
    caller = pre.deploy_contract(
        code=Op.CALL(gas=forwarded_gas, address=factory)
    )
    tx = Transaction(
        to=caller,
        state_gas_reservoir=new_account_state_gas,
        sender=pre.fund_eoa(),
    )

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

Parametrized Test Cases

This test generates 2 parametrized test cases across 1 fork.