test_extcodesize_empty_account_returns_zero()

Documentation for tests/amsterdam/eip8038_state_access_gas_cost_increase/test_ext_code_opcodes_gas.py::test_extcodesize_empty_account_returns_zero@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_extcodesize_empty_account_returns_zero --fork Amsterdam

Pay the surcharge on an empty target while EXTCODESIZE returns 0.

The size returned for an empty/non-existent account is 0, which confirms the target genuinely has no code: the measured COLD_ACCOUNT_ACCESS + WARM_ACCESS (cold) / 2 * WARM_ACCESS (warm) cost is therefore unambiguously the surcharge applied to an empty account, not an artifact of the target accidentally holding code.

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"])
def test_extcodesize_empty_account_returns_zero(
    state_test: StateTestFiller,
    env: Environment,
    pre: Alloc,
    fork: Fork,
    warm: bool,
) -> None:
    """
    Pay the surcharge on an empty target while ``EXTCODESIZE`` returns 0.

    The size returned for an empty/non-existent account is ``0``, which
    confirms the target genuinely has no code: the measured
    ``COLD_ACCOUNT_ACCESS + WARM_ACCESS`` (cold) / ``2 * WARM_ACCESS``
    (warm) cost is therefore unambiguously the surcharge applied to an
    empty account, not an artifact of the target accidentally holding code.
    """
    # Never deployed: no code, no balance, non-existent account.
    empty_addr = pre.nonexistent_account()

    expected_gas = Op.EXTCODESIZE(address_warm=warm).gas_cost(fork)

    # Measure the access cost and, separately, store the returned size so
    # the empty-account 0 result is asserted alongside the pricing. The
    # measured opcode carries the runtime warmth so the overhead reduces to
    # the address PUSH alone.
    storage = Storage()
    measured_code = Op.EXTCODESIZE.with_metadata(address_warm=warm)(empty_addr)
    gas_slot = storage.store_next(expected_gas, "extcodesize_empty_gas")
    size_slot = storage.store_next(0, "extcodesize_empty_size")
    code = CodeGasMeasure(
        code=measured_code,
        overhead_cost=measured_code.gas_cost(fork)
        - Op.EXTCODESIZE(address_warm=warm).gas_cost(fork),
        extra_stack_items=1,
        sstore_key=gas_slot,
    ) + Op.SSTORE(size_slot, Op.EXTCODESIZE(empty_addr))
    measure_address = pre.deploy_contract(code=code)

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

Parametrized Test Cases

This test generates 2 parametrized test cases across 1 fork.