test_swapn_gas_cost_boundary()

Documentation for tests/amsterdam/eip8024_dupn_swapn_exchange/test_swapn.py::test_swapn_gas_cost_boundary@c74f1a67.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip8024_dupn_swapn_exchange/test_swapn.py::test_swapn_gas_cost_boundary --fork Amsterdam

Test SWAPN at the gas cost boundary.

SWAPN is invoked in a callee that receives exactly its execution cost plus gas_cost_delta. The caller records the CALL result: a negative delta starves SWAPN of its base gas (3) and the sub-call runs out of gas (result 0); a zero or positive delta succeeds (result 1).

Source code in tests/amsterdam/eip8024_dupn_swapn_exchange/test_swapn.py

@EIPChecklist.Opcode.Test.GasUsage.Normal()
@EIPChecklist.Opcode.Test.GasUsage.OutOfGasExecution()
@EIPChecklist.Opcode.Test.GasUsage.ExtraGas()
@pytest.mark.parametrize("gas_cost_delta", [-2, -1, 0, 1, 2])
def test_swapn_gas_cost_boundary(
    gas_cost_delta: int,
    pre: Alloc,
    fork: Fork,
    state_test: StateTestFiller,
) -> None:
    """
    Test SWAPN at the gas cost boundary.

    SWAPN is invoked in a callee that receives exactly its execution cost
    plus `gas_cost_delta`. The caller records the CALL result: a negative
    delta starves SWAPN of its base gas (3) and the sub-call runs out of
    gas (result 0); a zero or positive delta succeeds (result 1).
    """
    # SWAPN with decoded value n swaps position 1 with position (n+1), so
    # it needs stack_index + 1 items on the stack.
    stack_index = Spec.MIN_STACK_INDEX  # 17

    code = Bytecode()
    for i in range(stack_index + 1):
        code += Op.PUSH1(i)
    code += Op.SWAPN[stack_index]

    contract_address = pre.deploy_contract(code=code)

    call_code = Op.SSTORE(
        0,
        Op.CALL(
            gas=code.gas_cost(fork) + gas_cost_delta,
            address=contract_address,
        ),
    )
    call_address = pre.deploy_contract(
        code=call_code,
        storage={0: 0xDEADBEEF},
    )

    tx = Transaction(to=call_address, sender=pre.fund_eoa())

    post = {call_address: Account(storage={0: 0 if gas_cost_delta < 0 else 1})}

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

Parametrized Test Cases

This test generates 5 parametrized test cases across 1 fork.