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System design patterns

Sharding, load balancing, CAP tradeoffs, and scaling patterns — interview and production ready.

2 matches

How to Mock a Metrics Decorator in Python with unittest.mock

This code demonstrates a timing decorator that wraps a function to measure execution time and prints the duration, with a unit test using unittest.mock to patch the print function and assert it was called.

decorators unittest.mock metrics

Python

import time
from functools import wraps
from unittest.mock import patch

def add_metrics(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        start = time.perf_counter()
        result = func(*args, **kwargs)
        elapsed = time.perf_counter() - start
        print(f"{func.__name__} took {elapsed:.6f}s…

15 0 Open

System design patterns medium

How to Mock a Timeout per Dependency Call in Python

This code demonstrates how to simulate and test per-call timeouts for external dependencies using Python's unittest.mock and a simple timing wrapper.

mock timeout unittest

Python

```python
import time
from unittest.mock import Mock, patch

def call_dependency(dependency, timeout):
    start = time.time()
    result = dependency.call()
    elapsed = time.time() - start
    if elapsed > timeout:
        raise TimeoutError(f"Dependency call took {elapsed:.2f}s, exceeding timeout {timeout}s")
    …

14 0 Open

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