test_bal_cross_tx_storage_chain()

Documentation for tests/amsterdam/eip7928_block_level_access_lists/test_block_access_lists.py::test_bal_cross_tx_storage_chain@622620d8.

Generate fixtures for these test cases for Amsterdam with:

fill -v tests/amsterdam/eip7928_block_level_access_lists/test_block_access_lists.py::test_bal_cross_tx_storage_chain --fork Amsterdam

Verify clients apply BAL state changes from prior transactions before executing later transactions in the same block.

Each Tx i seeds slots 0 and 1 with 1, then computes a Fibonacci-style sum into slot i: slot[i] = SLOAD(i-1) + SLOAD(i-2). Every Tx i>=2 depends on the two immediately preceding writes, so any parallelization that fails to apply a prior Tx's BAL storage change cascades into a wrong slot value and a different state root.

Source code in tests/amsterdam/eip7928_block_level_access_lists/test_block_access_lists.py

def test_bal_cross_tx_storage_chain(
    pre: Alloc,
    blockchain_test: BlockchainTestFiller,
) -> None:
    """
    Verify clients apply BAL state changes from prior transactions before
    executing later transactions in the same block.

    Each Tx i seeds slots 0 and 1 with `1`, then computes a
    Fibonacci-style sum into slot i: `slot[i] = SLOAD(i-1) + SLOAD(i-2)`.
    Every Tx i>=2 depends on the two immediately preceding writes, so
    any parallelization that fails to apply a prior Tx's BAL storage
    change cascades into a wrong slot value and a different state root.
    """
    chain_length = 8
    # i<2 seeds slot i with 1; i>=2 computes the Fibonacci sum.
    contract = pre.deploy_contract(
        code=Conditional(
            condition=Op.LT(Op.CALLDATALOAD(0), 2),
            if_true=Op.SSTORE(Op.CALLDATALOAD(0), 1),
            if_false=Op.SSTORE(
                Op.CALLDATALOAD(0),
                Op.ADD(
                    Op.SLOAD(Op.SUB(Op.CALLDATALOAD(0), 1)),
                    Op.SLOAD(Op.SUB(Op.CALLDATALOAD(0), 2)),
                ),
            ),
        ),
    )

    fib = [1, 1]
    for i in range(2, chain_length):
        fib.append(fib[i - 1] + fib[i - 2])

    txs = []
    senders = []
    for i in range(chain_length):
        sender = pre.fund_eoa()
        senders.append(sender)
        txs.append(
            Transaction(
                sender=sender,
                to=contract,
                data=Hash(i),
            )
        )

    account_expectations: dict = {
        sender: BalAccountExpectation(
            nonce_changes=[
                BalNonceChange(block_access_index=i + 1, post_nonce=1)
            ],
        )
        for i, sender in enumerate(senders)
    }
    account_expectations[contract] = BalAccountExpectation(
        storage_changes=[
            BalStorageSlot(
                slot=i,
                slot_changes=[
                    BalStorageChange(
                        block_access_index=i + 1, post_value=fib[i]
                    ),
                ],
            )
            for i in range(chain_length)
        ],
        nonce_changes=[],
        balance_changes=[],
        code_changes=[],
        storage_reads=[],
    )

    blockchain_test(
        pre=pre,
        blocks=[
            Block(
                txs=txs,
                expected_block_access_list=BlockAccessListExpectation(
                    account_expectations=account_expectations
                ),
            )
        ],
        post={
            contract: Account(
                storage={i: fib[i] for i in range(chain_length)}
            ),
        },
    )

Parametrized Test Cases

This test generates 1 parametrized test case across 1 fork.