test_swapn_preserves_other_stack_items()

Documentation for tests/amsterdam/eip8024_dupn_swapn_exchange/test_swapn.py::test_swapn_preserves_other_stack_items@9c2813ee.

Generate fixtures for these test cases for Amsterdam with:

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

Test SWAPN only swaps the specified items, leaving others unchanged.

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

def test_swapn_preserves_other_stack_items(
    pre: Alloc,
    state_test: StateTestFiller,
) -> None:
    """Test SWAPN only swaps the specified items, leaving others unchanged."""
    sender = pre.fund_eoa()

    # Use stack index 17 (smallest valid)
    # SWAPN with n=17 swaps position 1 with position 18, so need 18 items
    stack_index = 17
    stack_height = stack_index + 1  # Need 18 items

    # Create a stack with 18 distinct values
    code = Bytecode()
    for i in range(stack_height):
        code += Op.PUSH2(0x1000 + i)

    # SWAPN swaps top (position 1) with position 18
    # Pass stack index directly - encoder will handle encoding
    code += Op.SWAPN[stack_index]

    # Store all values to verify only the swapped ones changed
    for i in range(stack_height):
        code += Op.PUSH1(i) + Op.SSTORE

    code += Op.STOP

    contract_address = pre.deploy_contract(code=code)

    tx = Transaction(to=contract_address, sender=sender, gas_limit=1_000_000)

    # After swap: position 1 and position 18 are swapped
    # Original stack (top to bottom): 0x1011, 0x1010, ..., 0x1001, 0x1000
    # After SWAPN[0]: 0x1000, 0x1010, ..., 0x1001, 0x1011
    expected_storage = {}
    for i in range(stack_height):
        if i == 0:
            expected_storage[i] = 0x1000  # Was at bottom, now at top
        elif i == stack_height - 1:
            expected_storage[i] = 0x1011  # Was at top, now at bottom
        else:
            expected_storage[i] = 0x1000 + (stack_height - 1 - i)

    post = {contract_address: Account(storage=expected_storage)}

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

Parametrized Test Cases

This test generates 1 parametrized test case across 1 fork.