test_ext_code_double_read_empty_account()

Documentation for tests/amsterdam/eip8038_state_access_gas_cost_increase/test_ext_code_opcodes_gas.py::test_ext_code_double_read_empty_account@26332146.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip8038_state_access_gas_cost_increase/test_ext_code_opcodes_gas.py::test_ext_code_double_read_empty_account --fork Amsterdam

Charge the EIP-8038 double-read surcharge on an empty target.

EXTCODESIZE/EXTCODECOPY add the second, code-reading database access unconditionally: the surcharge is charged before the account is read, so an empty/non-existent target still costs COLD_ACCOUNT_ACCESS + WARM_ACCESS (cold) or 2 * WARM_ACCESS (warm), i.e. 3100 / 200, exactly as for a code-bearing target. This contrasts with EXTCODEHASH/BALANCE, which read only the account leaf and carry no surcharge (see test_extcodehash_empty_account). A client that skipped the second read for code-less accounts would be caught here.

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

@EIPChecklist.GasCostChanges.Test.GasUpdatesMeasurement()
@pytest.mark.parametrize("warm", [False, True], ids=["cold", "warm"])
@pytest.mark.parametrize("opcode", DOUBLE_READ_OPCODES)
def test_ext_code_double_read_empty_account(
    state_test: StateTestFiller,
    env: Environment,
    pre: Alloc,
    fork: Fork,
    warm: bool,
    opcode: Op,
) -> None:
    """
    Charge the EIP-8038 double-read surcharge on an empty target.

    ``EXTCODESIZE``/``EXTCODECOPY`` add the second, code-reading database
    access unconditionally: the surcharge is charged before the account is
    read, so an empty/non-existent target still costs
    ``COLD_ACCOUNT_ACCESS + WARM_ACCESS`` (cold) or ``2 * WARM_ACCESS``
    (warm), i.e. 3100 / 200, exactly as for a code-bearing target. This
    contrasts with ``EXTCODEHASH``/``BALANCE``, which read only the account
    leaf and carry no surcharge (see ``test_extcodehash_empty_account``). A
    client that skipped the second read for code-less accounts would be
    caught here.
    """
    # Never deployed: no code, no balance, non-existent account.
    empty_addr = pre.nonexistent_account()

    measured_code = opcode(address=empty_addr)
    # Subtract the opcode's OWN cold cost so the CodeGasMeasure overhead is
    # only the operand PUSH wrapper; the surcharge is part of the cold cost.
    overhead_cost = measured_code.gas_cost(fork) - opcode(
        address_warm=False
    ).gas_cost(fork)

    code_gas_measure = CodeGasMeasure(
        code=measured_code,
        overhead_cost=overhead_cost,
        extra_stack_items=opcode.pushed_stack_items,
    )
    measure_address = pre.deploy_contract(code=code_gas_measure)
    expected_gas = opcode(address_warm=warm).gas_cost(fork)

    tx = Transaction(
        to=measure_address,
        sender=pre.fund_eoa(),
        access_list=[AccessList(address=empty_addr, storage_keys=[])]
        if warm
        else None,
    )

    post = {measure_address: Account(storage={0: expected_gas})}

    state_test(env=env, pre=pre, post=post, tx=tx)

Parametrized Test Cases

This test generates 4 parametrized test cases across 1 fork.