Mocking loguru for Structured Logging in Python

import json
import sys
from io import StringIO
from unittest.mock import patch


def mock_loguru():
    # Simulate a structured logger with context binding
    class StructuredLogger:
        def __init__(self):
            self.context = {}

        def bind(self, **kwargs):
            logger = StructuredLogger()
            logger.context = {**self.context, **kwargs}
            return logger

        def info(self, message, **kwargs):
            log_entry = {"level": "INFO", "message": message, "context": self.context}
            log_entry.update(kwargs)
            print(json.dumps(log_entry))

    return StructuredLogger()


if __name__ == "__main__":
    # Test the mocked structured logger
    captured_output = StringIO()
    with patch("sys.stdout", captured_output):
        logger = mock_loguru()
        session_logger = logger.bind(user_id=42, session="abc123")
        session_logger.info("User logged in", event="login")

        root_logger = mock_loguru()
        root_logger.info("Server started", port=8080)

    print(captured_output.getvalue().strip())