def test_add_candidates():
"""Validate to include a new candidate"""
block = Block.genesis_block(timestamp=datetime(2000, 1, 1), difficulty=4, mining=True)
blockchain = BlockChain(block)
assert blockchain.last_block == block
assert blockchain.candidate_block is None
assert blockchain.num_blocks == 1
assert blockchain.is_valid
# Add a new candidate
assert blockchain.add_candidate(None, timestamp=datetime(2000, 1, 2))
assert blockchain.last_block == block
assert blockchain.candidate_block is not None
assert blockchain.num_blocks == 1
assert blockchain.is_valid
# Fail in the mining process
assert blockchain.mining_candidate(maximum_iter=0) is False
# Mining the candidate block
assert blockchain.mining_candidate()
# The blockchain is now valid
assert blockchain.last_block != block
assert blockchain.candidate_block is None
assert blockchain.num_blocks == 2
assert blockchain.is_valid
def test_basic_blockchain():
"""Test the basic blockchain"""
# BlockChain without values
blockchain = BlockChain()
assert blockchain.last_block is not None
assert blockchain.candidate_block is None
assert blockchain.num_blocks == 1
assert blockchain.is_valid
# Manual definition of the genesis block
block = Block.genesis_block(timestamp=datetime(2000, 1, 1), difficulty=4)
blockchain = BlockChain(block)
assert blockchain.last_block is None
assert blockchain.candidate_block == block
assert blockchain.num_blocks == 0
assert blockchain.is_valid is False
# it is not possible to add a new candidate
assert blockchain.add_candidate(None) is False
# Mining the candidate block
assert blockchain.mining_candidate()
# The blockchain is now valid
assert blockchain.last_block == block
assert blockchain.candidate_block is None
assert blockchain.num_blocks == 1
assert blockchain.is_valid
def test_mining_candidate():
"""Test mining candidate """
block = Block.genesis_block(timestamp=datetime(2000, 1, 1), difficulty=4, mining=True)
blockchain = BlockChain(block)
# Add a new candidate
assert blockchain.add_candidate(None, timestamp=datetime(2000, 1, 2))
assert blockchain.mining_candidate()
# Add an empty candidate
assert blockchain.add_candidate(None)
assert blockchain.mining_candidate()
# Add an invalid candidate (same date)
assert blockchain.add_candidate(None, timestamp=datetime(2000, 1, 1)) is False
assert blockchain.mining_candidate() is False
def test_block_repr():
"""Test the report function"""
block = Block.genesis_block(timestamp=datetime(2000, 1, 1), difficulty=4, mining=True)
blockchain = BlockChain(block)
assert repr(blockchain) == \
"Block: 0 (2000-01-01 00:00:00) - Hash: 015921ac58652b4e01d109cbb3ad10b55836e700a93e761036343ce8a82023ae\n"
for minute in range(1, 6):
blockchain.add_candidate(None, timestamp=datetime(2000, 1, 1, 0, minute, 0))
blockchain.mining_candidate()
assert repr(blockchain) == \
"Block: 5 (2000-01-01 00:05:00) - Hash: 0332726221951b73e5fb945914341aa1e92014151680375cdf8c632256dc9a54\n" + \
"Block: 4 (2000-01-01 00:04:00) - Hash: 0bf9e27631d08c326b15f7b459b47f91d9202c07ede76ce8503d636e09070402\n" + \
"Block: 3 (2000-01-01 00:03:00) - Hash: 07ded3c477dc38fe3d0bc434b2924430f81231a0d7878f906e2a655c1f17d444\n" + \
"Block: 2 (2000-01-01 00:02:00) - Hash: 0f8ed5b1cc4dca95c0c04b5b64a1ac409d636dbfd294282092f579d3872b1c15\n" + \
"Block: 1 (2000-01-01 00:01:00) - Hash: 037eeba6b1779e5edd02e4a2b4909260193adaab7ef8abaf04ddc8ab2fc39c95\n" + \
"\nand 1 block hidden"
def test_minimum_interval():
"""Test minimum interval period"""
block = Block.genesis_block(timestamp=datetime(2000, 1, 1, 0, 0, 0), difficulty=4, mining=True)
blockchain = BlockChain(block)
# A block in a minute
assert blockchain.add_candidate(None, timestamp=datetime(2000, 1, 1, 0, 1, 0))
assert blockchain.mining_candidate()
# A block in 30 seconds is not valid
assert blockchain.add_candidate(None, timestamp=datetime(2000, 1, 1, 0, 1, 30)) is False
def test_update_difficulty():
"""Test increase and decrease difficulty values"""
block = Block.genesis_block(timestamp=datetime(2000, 1, 1, 0, 0, 0), difficulty=4, mining=True)
blockchain = BlockChain(block)
# Change the interval for tests
blockchain.difficulty_interval = 2
# Blocks generates in a minute: the difficulty must increase
for minute in range(1, 7):
blockchain.add_candidate(None, timestamp=datetime(2000, 1, 1, 0, minute, 0))
blockchain.mining_candidate()
assert blockchain.chain[3].difficulty == 4
assert blockchain.chain[4].difficulty == 5
assert blockchain.chain[5].difficulty == 5
assert blockchain.chain[6].difficulty == 6
# Blocks generates in any eleven minutes: the difficulty must decrease
for minute in range(17, 60, 11):
blockchain.add_candidate(None, timestamp=datetime(2000, 1, 1, 0, minute, 0))
blockchain.mining_candidate()
blockchain.add_candidate(None, timestamp=datetime(2000, 1, 1, 1, 1, 0))
blockchain.mining_candidate()
assert blockchain.chain[9].difficulty == 7
assert blockchain.chain[10].difficulty == 6
def test_change_block_contains():
"""Test different attacks to the blockchain"""
data = ["Avocado", "Apple", "Cherry", "Orange", "Strawberry"]
block = Block.genesis_block(data[0], timestamp=datetime(2000, 1, 1), difficulty=4, mining=True)
blockchain = BlockChain(block)
for minute in range(1, len(data)):
assert blockchain.add_candidate(data[minute], timestamp=datetime(2000, 1, 1, 0, minute, 0))
assert blockchain.mining_candidate()
assert blockchain.is_valid
# Alter the blockchain data
blockchain.chain[2].data = 'Khaki'
assert blockchain.is_valid is False