test_sstore_restore_nonzero_refunds_write()

Documentation for tests/amsterdam/eip8038_state_access_gas_cost_increase/test_sstore_refunds.py::test_sstore_restore_nonzero_refunds_write@2867859a.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip8038_state_access_gas_cost_increase/test_sstore_refunds.py::test_sstore_restore_nonzero_refunds_write --fork Amsterdam

Restoring a non-zero-original slot refunds the write cost.

The slot is changed (charging STORAGE_WRITE) then restored to its original non-zero value, refunding STORAGE_WRITE. Gas is burned so the quotient cap does not bind and the full refund is observable.

Source code in tests/amsterdam/eip8038_state_access_gas_cost_increase/test_sstore_refunds.py

@EIPChecklist.GasRefundsChanges.Test.RefundCalculation()
@EIPChecklist.GasRefundsChanges.Test.RefundCalculation.Under()
def test_sstore_restore_nonzero_refunds_write(
    state_test: StateTestFiller,
    pre: Alloc,
    fork: Fork,
) -> None:
    """
    Restoring a non-zero-original slot refunds the write cost.

    The slot is changed (charging ``STORAGE_WRITE``) then restored to its
    original non-zero value, refunding ``STORAGE_WRITE``. Gas is
    burned so the quotient cap does not bind and the full refund is
    observable.
    """
    code = Op.SSTORE.with_metadata(
        key_warm=False,
        original_value=1,
        current_value=1,
        new_value=2,
    )(0, 2) + Op.SSTORE.with_metadata(
        key_warm=True,
        original_value=1,
        current_value=2,
        new_value=1,
    )(0, 1)
    burn = Op.JUMPDEST * 60_000
    code += burn

    contract = pre.deploy_contract(code=code, storage={0: 1})

    # Restoring the non-zero original refunds STORAGE_WRITE.
    storage_write = code.refund(fork)
    expected_cumulative = _cumulative_gas_used(code, fork)
    intrinsic = fork.transaction_intrinsic_cost_calculator()(
        return_cost_deducted_prior_execution=True
    )
    gross = intrinsic + code.execution_cost(fork)
    assert gross // 5 > storage_write
    assert expected_cumulative == gross - storage_write

    tx = Transaction(
        to=contract,
        sender=pre.fund_eoa(),
        expected_receipt=TransactionReceipt(
            cumulative_gas_used=expected_cumulative
        ),
    )

    post = {contract: Account(storage={0: 1})}
    state_test(pre=pre, post=post, tx=tx)

Parametrized Test Cases

This test generates 1 parametrized test case across 1 fork.