How to Simulate Distributed Transactions in Python with a Mock

class Transaction:
    def __init__(self, id):
        self.id = id
        self.operations = []
        self.committed = False

    def add_operation(self, op, data):
        self.operations.append((op, data))

    def commit(self):
        if not self.operations:
            raise ValueError("No operations to commit")
        self.committed = True
        print(f"Transaction {self.id} committed with {len(self.operations)} operations")

    def rollback(self):
        self.operations.clear()
        print(f"Transaction {self.id} rolled back")

    def simulate_failure(self):
        print(f"Transaction {self.id} failed before commit")
        self.rollback()


class FakeDatabase:
    def __init__(self):
        self.transactions = []

    def execute(self, transaction):
        try:
            transaction.commit()
            self.transactions.append(transaction)
        except ValueError as e:
            print(f"Error: {e}")


if __name__ == "__main__":
    db = FakeDatabase()
    txn1 = Transaction("T1")
    txn1.add_operation("INSERT", {"user": "alice", "amount": 100})
    txn1.add_operation("UPDATE", {"balance": 150})

    txn2 = Transaction("T2")
    txn2.add_operation("DELETE", {"id": 42})

    txn1.commit()
    txn2.simulate_failure()

    db.execute(txn1)
    db.execute(txn2)