test_reservoir_restored_after_child_spill_and_revert()

Documentation for tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_call.py::test_reservoir_restored_after_child_spill_and_revert@5c024cbb.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip8037_state_creation_gas_cost_increase/test_state_gas_call.py::test_reservoir_restored_after_child_spill_and_revert --fork Amsterdam

Test all state gas recovered when child spills then reverts.

The child performs two SSTOREs (zero-to-nonzero) but only one SSTORE's worth of state gas fits in the reservoir, so the second spills into gas_left. The child then REVERTs. Because state changes are rolled back, the state gas is refilled LIFO: the spilled portion returns to gas_left and the reservoir-funded portion restores the reservoir to its start value. The parent then performs two SSTOREs, drawing one from the restored reservoir and spilling the other from the recovered gas_left.

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

@pytest.mark.valid_from("EIP8037")
def test_reservoir_restored_after_child_spill_and_revert(
    state_test: StateTestFiller,
    pre: Alloc,
    fork: Fork,
) -> None:
    """
    Test all state gas recovered when child spills then reverts.

    The child performs two SSTOREs (zero-to-nonzero) but only one
    SSTORE's worth of state gas fits in the reservoir, so the second
    spills into `gas_left`. The child then REVERTs. Because state
    changes are rolled back, the state gas is refilled LIFO: the
    spilled portion returns to `gas_left` and the reservoir-funded
    portion restores the reservoir to its start value. The parent
    then performs two SSTOREs, drawing one from the restored
    reservoir and spilling the other from the recovered `gas_left`.
    """
    sstore_state_gas = Op.SSTORE(new_value=1).state_cost(fork)

    # Child does two SSTOREs then reverts — the second SSTORE's
    # state gas spills from the reservoir into `gas_left`
    child = pre.deploy_contract(
        code=(Op.SSTORE(0, 1) + Op.SSTORE(1, 1) + Op.REVERT(0, 0)),
    )

    parent_storage = Storage()
    parent = pre.deploy_contract(
        code=(
            Op.POP(Op.CALL(gas=500_000, address=child))
            # State gas recovered LIFO: the spilled SSTORE returns to
            # gas_left, the other restores the reservoir
            + Op.SSTORE(parent_storage.store_next(1), 1)
            + Op.SSTORE(parent_storage.store_next(1), 1)
        ),
    )

    # Reservoir = 1 SSTORE's worth of state gas — child will spill
    tx = Transaction(
        to=parent,
        state_gas_reservoir=sstore_state_gas,
        sender=pre.fund_eoa(),
    )

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

Parametrized Test Cases

This test generates 1 parametrized test case across 1 fork.