`test_floor_cost_not_reduced_by_refunds()`¶

Documentation for tests/amsterdam/eip7976_increase_calldata_floor_cost/test_additional_coverage.py::TestRefundCapInteraction::test_floor_cost_not_reduced_by_refunds@9c2813ee.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip7976_increase_calldata_floor_cost/test_additional_coverage.py::TestRefundCapInteraction::test_floor_cost_not_reduced_by_refunds --fork Amsterdam

Test that the ⅕ refund cap interacts correctly with floor cost.

Source code in tests/amsterdam/eip7976_increase_calldata_floor_cost/test_additional_coverage.py

class TestRefundCapInteraction:
    """Test that the 1/5 refund cap interacts correctly with floor cost."""

    @pytest.fixture
    def sender(self, pre: Alloc) -> Address:
        """Create sender account."""
        return pre.fund_eoa()

    def test_refund_cap_at_one_fifth(
        self,
        state_test: StateTestFiller,
        pre: Alloc,
        sender: Address,
        fork: Fork,
    ) -> None:
        """
        Test that refunds are capped at the fork max refund quotient.

        Even if the refund counter is high, the actual refund cannot exceed
        the fork cap. Use minimal calldata to avoid floor cost interference.
        """
        # Use minimal calldata so floor cost doesn't dominate
        calldata = Bytes(b"")

        # Deploy contract that clears multiple storage slots
        # This generates a large refund counter
        num_slots = 10
        code = Bytecode()
        storage = {i: 1 for i in range(num_slots)}  # noqa: C420

        for i in range(num_slots):
            code += Op.SSTORE(i, 0, original_value=1, new_value=0)

        code += Op.STOP
        contract = pre.deploy_contract(
            code,
            storage=storage,  # type: ignore[arg-type]
        )

        # Calculate costs
        intrinsic_cost_calculator = (
            fork.transaction_intrinsic_cost_calculator()
        )
        intrinsic_cost_before_execution = intrinsic_cost_calculator(
            calldata=calldata,
            contract_creation=False,
            access_list=None,
            authorization_list_or_count=None,
            return_cost_deducted_prior_execution=True,
        )

        execution_gas = code.gas_cost(fork)

        total_gas_before_refund = (
            intrinsic_cost_before_execution + execution_gas
        )

        refund_counter = code.refund(fork)

        # Actual refund is capped by the fork max refund quotient.
        refund_cap = total_gas_before_refund // fork.max_refund_quotient()
        actual_refund = min(refund_counter, refund_cap)

        # Verify that refund counter exceeds cap
        assert refund_counter > refund_cap, (
            "Test requires refund_counter > refund cap"
        )

        # Gas after refund (floor cost is minimal with empty calldata)
        expected_gas = total_gas_before_refund - actual_refund

        tx = Transaction(
            sender=sender,
            to=contract,
            data=calldata,
            gas_limit=total_gas_before_refund,
        )

        tx.expected_receipt = TransactionReceipt(
            cumulative_gas_used=expected_gas
        )

        # Verify all storage slots are cleared
        expected_storage = dict.fromkeys(range(num_slots), 0)

        state_test(
            pre=pre,
            post={
                contract: {
                    "storage": expected_storage,
                }
            },
            tx=tx,
        )

    def test_floor_cost_not_reduced_by_refunds(
        self,
        state_test: StateTestFiller,
        pre: Alloc,
        sender: Address,
        fork: Fork,
    ) -> None:
        """
        Verify floor cost acts as a true floor and is never reduced.

        Even with large refunds, the transaction must pay at least the
        floor cost.
        """
        # Use calldata that strongly triggers floor cost
        calldata = Bytes(b"\x01" * 1000)

        # Deploy contract that clears storage
        code = Op.SSTORE(0, 0, original_value=1, new_value=0) + Op.STOP
        contract = pre.deploy_contract(
            code,
            storage={0: 1},
        )

        # Calculate costs
        floor_cost_calculator = fork.transaction_data_floor_cost_calculator()
        floor_cost = floor_cost_calculator(data=calldata)

        intrinsic_cost_calculator = (
            fork.transaction_intrinsic_cost_calculator()
        )
        intrinsic_cost_before_execution = intrinsic_cost_calculator(
            calldata=calldata,
            contract_creation=False,
            access_list=None,
            authorization_list_or_count=None,
            return_cost_deducted_prior_execution=True,
        )

        execution_gas = code.gas_cost(fork)

        total_gas_before_refund = (
            intrinsic_cost_before_execution + execution_gas
        )
        refund = min(
            code.refund(fork),
            total_gas_before_refund // fork.max_refund_quotient(),
        )
        gas_after_refund = total_gas_before_refund - refund

        # Even after refund, we should pay at least floor cost
        expected_gas = max(gas_after_refund, floor_cost)

        # Verify floor cost is the dominant factor
        assert expected_gas == floor_cost, (
            "Floor cost should dominate for data-heavy transaction"
        )

        # Gas limit must satisfy both execution needs and floor cost
        gas_limit = max(total_gas_before_refund, floor_cost)

        tx = Transaction(
            sender=sender,
            to=contract,
            data=calldata,
            gas_limit=gas_limit,
        )

        tx.expected_receipt = TransactionReceipt(
            cumulative_gas_used=expected_gas
        )

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

`test_refund_cap_at_one_fifth(state_test, pre, sender, fork)` ¶

Test that refunds are capped at the fork max refund quotient.

Even if the refund counter is high, the actual refund cannot exceed the fork cap. Use minimal calldata to avoid floor cost interference.

Source code in tests/amsterdam/eip7976_increase_calldata_floor_cost/test_additional_coverage.py

def test_refund_cap_at_one_fifth(
    self,
    state_test: StateTestFiller,
    pre: Alloc,
    sender: Address,
    fork: Fork,
) -> None:
    """
    Test that refunds are capped at the fork max refund quotient.

    Even if the refund counter is high, the actual refund cannot exceed
    the fork cap. Use minimal calldata to avoid floor cost interference.
    """
    # Use minimal calldata so floor cost doesn't dominate
    calldata = Bytes(b"")

    # Deploy contract that clears multiple storage slots
    # This generates a large refund counter
    num_slots = 10
    code = Bytecode()
    storage = {i: 1 for i in range(num_slots)}  # noqa: C420

    for i in range(num_slots):
        code += Op.SSTORE(i, 0, original_value=1, new_value=0)

    code += Op.STOP
    contract = pre.deploy_contract(
        code,
        storage=storage,  # type: ignore[arg-type]
    )

    # Calculate costs
    intrinsic_cost_calculator = (
        fork.transaction_intrinsic_cost_calculator()
    )
    intrinsic_cost_before_execution = intrinsic_cost_calculator(
        calldata=calldata,
        contract_creation=False,
        access_list=None,
        authorization_list_or_count=None,
        return_cost_deducted_prior_execution=True,
    )

    execution_gas = code.gas_cost(fork)

    total_gas_before_refund = (
        intrinsic_cost_before_execution + execution_gas
    )

    refund_counter = code.refund(fork)

    # Actual refund is capped by the fork max refund quotient.
    refund_cap = total_gas_before_refund // fork.max_refund_quotient()
    actual_refund = min(refund_counter, refund_cap)

    # Verify that refund counter exceeds cap
    assert refund_counter > refund_cap, (
        "Test requires refund_counter > refund cap"
    )

    # Gas after refund (floor cost is minimal with empty calldata)
    expected_gas = total_gas_before_refund - actual_refund

    tx = Transaction(
        sender=sender,
        to=contract,
        data=calldata,
        gas_limit=total_gas_before_refund,
    )

    tx.expected_receipt = TransactionReceipt(
        cumulative_gas_used=expected_gas
    )

    # Verify all storage slots are cleared
    expected_storage = dict.fromkeys(range(num_slots), 0)

    state_test(
        pre=pre,
        post={
            contract: {
                "storage": expected_storage,
            }
        },
        tx=tx,
    )