def test_is_block_valid_with_maladjusted_difficulty(prev_block, block):
adjusted_difficulty = 10
block.difficulty = adjusted_difficulty
block.hash = f"{'0' * adjusted_difficulty}abc123"
with pytest.raises(Exception, match="Difficulty adjustment error."):
Block.is_block_valid(prev_block, block)
def test_is_block_valid_with_invalid_hash(prev_block, block):
block.hash = "000000000000000abc123"
with pytest.raises(
Exception,
match="Value error. A Proof of Work requirement has not been met."
):
Block.is_block_valid(prev_block, block)
def is_chain_valid(chain):
"""
A Blockchain is said to be valid if:
1. The Genesis block is valid.
2. All the blocks in the blockchain are valid.
"""
if chain[0] != Block.genesis():
raise Exception("Genesis block was invalid")
for i in range(1, len(chain)):
last_block = chain[i - 1]
block = chain[i]
Block.is_block_valid(last_block, block)
def is_chain_valid(chain):
"""
Validate the chain
"""
if chain[0] != Block.genesis_block():
raise Exception("The genesis block is not valid")
for i in range(1, len(chain)):
block = chain[i]
last_block = chain[i - 1]
Block.is_block_valid(last_block, block)
BlockChain.is_transaction_chain_valid(chain)
def is_chain_valid(blockchain):
"""
Validate incoming blockchain qua the following ruleset:
- the blockchain must begin with a valid genesis block
- blocks must be formatted properly
"""
if (blockchain[0] != Block.genesis()):
raise Exception("The genesis block must be valid.")
for i in range(1, len(blockchain)):
block = blockchain[i]
prev_block = blockchain[i - 1]
Block.is_block_valid(prev_block, block)
def test_is_block_valid():
last_block = Block.genesis_block()
block = Block.mine_block(last_block, "dummy data")
Block.is_block_valid(last_block, block)
# bad last hash check
block = Block.mine_block(last_block, "dummy data")
block.last_hash = "evil_last_hash"
with pytest.raises(
Exception,
match=
"The last block hash and the last hash of the new block should match"
):
Block.is_block_valid(last_block, block)
# bad proof of work
block = Block.mine_block(last_block, "dummy data")
block.hash = "aaaaa"
with pytest.raises(Exception, match="Proof of work requirement not met"):
Block.is_block_valid(last_block, block)
# difficulty tampered
difficulty = 10
block = Block.mine_block(last_block, "dummy data")
block.difficulty = difficulty
block.hash = f"{'0' * difficulty}1111a"
with pytest.raises(Exception,
match="The block difficulty must only adjust by 1"):
Block.is_block_valid(last_block, block)
def test_block_valid_wrong_hash(last_block, mined_block):
mined_block.hash = "0x%sabcd" % ('0' * mined_block.difficulty)
with pytest.raises(Exception, match='The block hash was not valid'):
Block.is_block_valid(last_block, mined_block)
def test_block_valid_wrong_difficulty(last_block, mined_block):
jumped_difficulty = 10
mined_block.difficulty = jumped_difficulty
mined_block.hash = "0x%sabcd" % ('0' * jumped_difficulty)
with pytest.raises(Exception, match='The block difficulty was not valid'):
Block.is_block_valid(last_block, mined_block)
def test_block_valid_wrong_pow(last_block, mined_block):
mined_block.hash = '0xabcd'
with pytest.raises(Exception,
match='The proof of work requirement was not met'):
Block.is_block_valid(last_block, mined_block)
def test_block_valid_wrong_last_hash(last_block, mined_block):
mined_block.last_hash = 'wrong_last_hash'
with pytest.raises(Exception,
match='The hash of last block did not match'):
Block.is_block_valid(last_block, mined_block)
def test_block_valid(last_block, mined_block):
Block.is_block_valid(last_block, mined_block)
def test_is_block_valid_with_invalid_prev_hash(prev_block, block):
block.prev_hash = "invalidate"
with pytest.raises(Exception, match="Value previous hash is invalid."):
Block.is_block_valid(prev_block, block)
def test_is_block_valid(prev_block, block):
Block.is_block_valid(prev_block, block)