def test_invalid_chain(blockchain_3b):
'''
Purpose:
Test whether a given blockchain is invalid by corrupting it's
genesis block and performing validation.
'''
blockchain_3b.chain[0].hash = 'test-bad-hash'
with pytest.raises(Exception, match='genesis block must be valid.'):
Blockchain.is_valid(blockchain_3b.chain)
def test_valid_chain(blockchain_3b):
'''
Purpose:
Test whether a given blockchain is valid.
'''
Blockchain.is_valid(blockchain_3b.chain)
