def test_is_tx_valid_when_invalid_outputs():
sender_wallet = Wallet()
transaction = Transaction(sender_wallet, "b64e8ac4", 50)
transaction.output[sender_wallet.address] = 9001
with pytest.raises(Exception, match="Invalid transaction."):
Transaction.is_tx_valid(transaction)
def test_block_reward_tx_when_invalid_reward_amt():
wallet = Wallet()
reward_tx = Transaction.generate_reward_transaction(wallet)
reward_tx.output[wallet.address] = 100000
with pytest.raises(Exception, match="Invalid block reward transaction."):
Transaction.is_tx_valid(reward_tx)
def is_tx_chain_valid(blockchain):
"""
Validate incoming blockchain comprised of blocks with Tx therein qua the following ruleset:
- each Tx occurs once in the blockchain (i.e. 'double spend')
- there is only one valid reward Tx per block
- transaction obj must be intrinsically valid
"""
# Tx tracked by id, raise if duplicate
tx_tracking_pool = set()
# unwrap blockchain, unwrap blocks therein, deserialize ea block's Tx and parse them
for i in range(len(blockchain)):
block = blockchain[i]
mining_reward_extant = False
for serialized_tx in block.data:
deserialized_tx = Transaction.deserialize_from_json(
serialized_tx)
# if Tx already exists
if (deserialized_tx.id in tx_tracking_pool):
raise Exception(
f"Transaction {deserialized_tx.id} is not unique; this transaction is therefore invalid."
)
# add Tx to tracking pool
tx_tracking_pool.add(deserialized_tx.id)
# if Tx is a block reward, only validate against reward fields
if (deserialized_tx.input == MINING_REWARD_INPUT):
if (mining_reward_extant):
raise Exception(f"""
There can only be one mining reward per block.
Evaluation of block with hash: {block.hash} recommended."""
)
mining_reward_extant = True
else:
# recalc balance after every Tx to prevent input tamper
blockchain_provenance = Blockchain()
blockchain_provenance.chain = blockchain[0:i]
balance_provenance = Wallet.calculate_balance(
blockchain_provenance,
deserialized_tx.input["address"])
if (balance_provenance != deserialized_tx.input["amount"]):
raise Exception(
f"Transaction {deserialized_tx.id} contains an invalid input amount."
)
# last, run validator to check format
Transaction.is_tx_valid(deserialized_tx)
def test_block_reward_tx_when_valid_tx():
reward_tx = Transaction.generate_reward_transaction(Wallet())
Transaction.is_tx_valid(reward_tx)
def test_is_tx_valid():
Transaction.is_tx_valid(Transaction(Wallet(), "b64e8ac4", 50))
def test_block_reward_tx_when_exceeds_recipients():
reward_tx = Transaction.generate_reward_transaction(Wallet())
reward_tx.output["second_and_invalid_recipient"] = 100
with pytest.raises(Exception, match="Invalid block reward transaction."):
Transaction.is_tx_valid(reward_tx)
