def test_mined_block_difficulty_limits_at_1():
last_block = Block(time.time_ns(), 'test_last_hash', 'test_hash',
'test_data', 1, 0)
time.sleep(MINE_RATE / SECONDS)
mined_block = Block.mine_block(last_block, 'bar')
assert mined_block.difficulty == 1
def test_is_valid_block_jumped_difficulty(last_block, block):
jumped_difficulty = 10
block.difficulty = jumped_difficulty
block.hash = f'{"0" * jumped_difficulty}111abc'
with pytest.raises(Exception, match='difficulty must only adjust by 1'):
Block.is_valid_block(last_block, block)
def test_slowly_mined_block():
last_block = Block.mine_block(Block.genesis(), 'foo')
#sleep(MINE_RATE/SECONDS) cause that mine algorythm will decrease difficulty
time.sleep(MINE_RATE / SECONDS)
mined_block = Block.mine_block(last_block, 'bar')
assert mined_block.difficulty == last_block.difficulty - 1
def test_mine_block():
last_block = Block.genesis()
data = 'test-data'
block = Block.mine_block(last_block, data)
assert isinstance(block, Block)
assert block.data == data
assert block.last_hash == last_block.hash
assert hex_to_binary(
block.hash)[0:block.difficulty] == '0' * block.difficulty
def test_genesis():
genesis = Block.genesis()
assert isinstance(genesis, Block)
for key, value in GENESIS_DATA.items():
getattr(genesis, key) == value
def is_valid_chain(chain):
"""
Validate the incoming chain.
Enforce the following rules of the blockchain:
- the chain must start with the genesis block
- blocks must be formatted correctly
"""
if chain[0] != Block.genesis():
raise Exception('The genesis block must be valid')
# skipping genesis block in validaiton process
for i in range(1, len(chain)):
block = chain[i]
last_block = chain[i - 1]
Block.is_valid_block(last_block, block)
Blockchain.is_valid_transaction_chain(chain)
def from_json(chain_json):
"""
Deserialize a list of serialized blocks into a Blockchain instance.
The results will containg a chain list of Block instances.
"""
blockchain = Blockchain()
blockchain.chain = list(
map(lambda block_json: Block.from_json(block_json), chain_json))
return blockchain
def message(self, pubnub, message_object):
print(
f'\n-- Channel: {message_object.channel} | Message: {message_object.message}'
)
if message_object.channel == CHANNELS['BLOCK']:
block = Block.from_json(message_object.message)
# [:] -> all the elements in the array, in that case all blocks in chain
potential_chain = self.blockchain.chain[:]
potential_chain.append(block)
try:
self.blockchain.replace_chain(potential_chain)
self.transaction_pool.clear_blockchain_transactions(
self.blockchain)
print('\n -- Successfully replaced the local chain')
except Exception as e:
print(f'\n -- Did not replace chain: {e}')
elif message_object.channel == CHANNELS['TRANSACTION']:
transaction = Transaction.from_json(message_object.message)
self.transaction_pool.set_transaction(transaction)
print('\n -- Set the new transaction in the transaction pool')
def last_block():
return Block.genesis()
def test_is_valid_block_bad_proof_of_work(last_block, block):
block.hash = 'fff'
with pytest.raises(Exception,
match='proof of work requirement was not meet'):
Block.is_valid_block(last_block, block)
def add_block(self, data):
self.chain.append(Block.mine_block(self.chain[-1], data))
def block(last_block):
return Block.mine_block(last_block, 'test_data')
def __init__(self):
self.chain = [Block.genesis()]
def test_is_valid_block_bad_block_hash(last_block, block):
block.hash = '0000000000bbbabc'
with pytest.raises(Exception, match='block hash must be correct'):
Block.is_valid_block(last_block, block)
def test_is_valid_block(last_block, block):
Block.is_valid_block(last_block, block)
def test_is_valid_block_bad_last_hash(last_block, block):
block.last_hash = 'evil_last_hash'
with pytest.raises(Exception, match='last_hash must be correct'):
Block.is_valid_block(last_block, block)
def test_quickly_mined_block():
last_block = Block.mine_block(Block.genesis(), 'foo')
mined_block = Block.mine_block(last_block, 'bar')
assert mined_block.difficulty == last_block.difficulty + 1