How to Mock a Try Confirm Cancel Pattern in Python

Define a simple class with confirm and cancel methods, execute a try confirm with error handling, and print the final state.

Easy Python 3.9+ Aug 9, 2026 Reliability & rate limiting 13 views 0 copies

try-except mock class error-handling

Python code

25 lines

Python 3.9+

class TCC:
    def __init__(self):
        self.confirmed = False
        self.cancelled = False

    def confirm(self):
        self.confirmed = True
        return "confirmed"

    def cancel(self):
        self.cancelled = True
        return "cancelled"

    def try_confirm(self):
        try:
            result = self.confirm()
            print(f"Try confirm → {result}")
        except Exception as e:
            print(f"Try confirm failed: {e}")

if __name__ == "__main__":
    tcc = TCC()
    tcc.try_confirm()
    print(f"Cancel result: {tcc.cancel()}")
    print(f"Final state: confirmed={tcc.confirmed}, cancelled={tcc.cancelled}")

Output

stdout

Try confirm → confirmed
Cancel result: cancelled
Final state: confirmed=True, cancelled=True

How it works

The try_confirm method wraps the confirm call in a try-except block, printing a success message when no error occurs. The confirm and cancel methods simply set boolean flags and return string results. Running the main block demonstrates the sequence: a successful confirm, a cancel, and the final state. This pattern is useful for testing mockable operations where you want to ensure fallback behavior on exceptions.

Common mistakes

Forgetting to reset flags before reusing the object
Not catching specific exceptions in the try block
Assuming the return value is used when it's only printed

Variations

Use a mock library like unittest.mock to replace confirm or cancel in tests
Add retry logic with exponential backoff inside try_confirm

Real-world use cases

Testing service interactions where confirmation or cancellation must be idempotent.
Building retry mechanisms for unreliable remote calls in distributed systems.
Implementing user-facing actions that need explicit success or failure logging.

How to Mock a Try Confirm Cancel Pattern in Python

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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