How to Mock zlib Compression for Cache Values in Python

import zlib
from unittest.mock import patch

def compress_value(data: bytes) -> bytes:
    """Compress data using zlib and return the compressed bytes."""
    return zlib.compress(data)

def decompress_value(compressed: bytes) -> bytes:
    """Decompress zlib data and return the original bytes."""
    return zlib.decompress(compressed)

if __name__ == "__main__":
    original = b"cache_value_to_be_compressed"
    
    # Real compression/decompression flow
    compressed = compress_value(original)
    decompressed = decompress_value(compressed)
    
    print(f"Original size: {len(original)} bytes")
    print(f"Compressed size: {len(compressed)} bytes")
    print(f"Round-trip successful: {original == decompressed}")
    
    # Mock the compress function to simulate a different behavior
    with patch("__main__.compress_value", return_value=b"mocked_compressed_data") as mock_compress:
        mocked_result = compress_value(original)
        print(f"Mocked compress result: {mocked_result}")
        mock_compress.assert_called_once_with(original)