How to Serialize Cache Values with JSON and Pickle in Python

import json
import pickle
from unittest.mock import Mock

def serialize(value, method="json"):
    """Serialize a cache value using JSON or pickle with type checking."""
    if method == "json":
        try:
            return json.dumps(value).encode("utf-8")
        except TypeError as e:
            raise ValueError(f"Cannot serialize {type(value).__name__} with JSON: {e}")
    elif method == "pickle":
        return pickle.dumps(value)
    else:
        raise ValueError(f"Unknown serialization method: {method}")

if __name__ == "__main__":
    # Test with basic types
    cache_data = {"user": "alice", "count": 42, "tags": ["a", "b"]}
    json_bytes = serialize(cache_data, "json")
    pickled_bytes = serialize(cache_data, "pickle")
    print(f"JSON: {json_bytes}")
    print(f"Pickle: {pickled_bytes[:50]}...")
    
    # Mock object that mimics a real cache value (e.g., from a test)
    mock_value = Mock()
    mock_value.data = {"status": "cached"}
    print(f"Mock repr: {mock_value!r}")
    
    # Note: JSON cannot handle Mock objects
    try:
        serialize(mock_value, "json")
    except ValueError as e:
        print(f"JSON mock error: {e}")