def test_mine_block():
last_block = Block.genesis_block()
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 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_block():
raise Exception('The genesis block must be valid.')
for i in range(1, len(chain)):
block = chain[i]
# Previous block:
last_block = chain[i - 1]
Block.is_valid_block(last_block, block)
Blockchain.is_valid_transaction_chain(chain)
def __init__(self):
self.chain = [Block.genesis_block()]
def last_block():
return Block.genesis_block()
def test_decreased_difficulty_mined_block():
last_block = Block.mine_block(Block.genesis_block(), 'foo')
time.sleep(MINE_RATE / SECONDS)
mined_block = Block.mine_block(last_block, 'bar')
assert mined_block.difficulty == last_block.difficulty - 1
def test_increased_difficulty_mined_block():
last_block = Block.mine_block(Block.genesis_block(), 'foo')
mined_block = Block.mine_block(last_block, 'bar')
assert mined_block.difficulty == last_block.difficulty + 1
def test_genesis():
genesis = Block.genesis_block()
assert isinstance(genesis, Block)
for key, value in GENESIS_DATA.items():
getattr(genesis, key) == value