def test_valid_block_invalid_hash(last_block, block):
'''
Purpose:
Test that the block must have a valid hash. Corrupt the block's
hash and validate.
'''
block.hash = '0000000000000000bbbabc'
with pytest.raises(Exception, match='must have a proper hash reference.'):
Block.is_valid(last_block, block)
def test_invalid_block(last_block, block):
'''
Purpose:
Test that a block is invalid by corrupting its last_hash value and
then validating.
'''
block.last_hash = 'test-bad-hash'
with pytest.raises(Exception,
match="must have a proper last_hash reference."):
Block.is_valid(last_block, block)
def test_valid_block_jumped_difficulty(last_block, block):
'''
Purpose:
Test that the a valid block cannot adjust its diffuclty any more or
less than 1. Set block difficulty to greater than 1 and validate.
'''
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(last_block, block)
def test_valid_block_invalid_proof_of_work(last_block, block):
'''
Purpose:
Test that a block is not valid if the Proof-of-Work requirement is
not met. Invalidate the Proof-of-Work by corrupting the block's
hash value.
'''
block.hash = 'fff'
with pytest.raises(Exception,
match='did not meet the Proof of Work Requirement.'):
Block.is_valid(last_block, block)
def is_valid(chain):
'''
Validate a block-chain by enforcing the following rules:
- The chain must start with the genesis block.
- Each block in the chain must be formatted correctly.
'''
if chain[0] != Block.genesis():
raise Exception('The genesis block must be valid.')
for i in range(1, len(chain)):
block = chain[i]
last_block = chain[i - 1]
Block.is_valid(last_block, block)
Blockchain.is_valid_trans_chain(chain)
def test_valid_block(last_block, block):
'''
Purpose:
Test that a block is valid.
'''
Block.is_valid(last_block, block)