Help designing an integration with `logot` (hashtag1072)

[vikramsubramanian]

I've recently released a 0.1.0 preview of a log testing library called [logot]( It provides a nice fixture for testing [complex log patterns]( which I've found very useful when testing multithreaded and async codebases.

I'd like to provide a loguru integration. 🤗Since I'm not hugely familiar with loguru, I was hoping you'd have some advice on what a good integration would look like.

There are a couple of sticking points that I'd like to nail before committing to a v1.0.0 API.

hashtag Log capture

Currently, stdlib logging capture is enabled with a [context manager method](

from logot import Logot

with Logot().capturing() as logot:
    pass

Since the loguru integration would be an optional extra, a freestanding context manager could be provided like this:

from logot.contrib.loguru import capturing

with capturing(Logot()) as logot:
   ...

It's a bit awkward having a freestanding context manager for 3rd party integrations, so an alternative would be a capturing backend approach:

from logot.contrib.loguru import LoguruCapture

with Logot().capturing(LoguruCapture):
   pass

Any arguments given to capturing would be propagated to the LoguruCapture constructor. This would then unify capture between stdlib logging and loguru logging. The default capture backend would be the stdlib capture, and an ` would ensure good typing. 💪

The alternative is a whole Logot subclass just for loguru, which seems heavyweight and unpleasant. 🤮

hashtaghashtag Log message matching

Rather than awkward regexes, logot lets you [match log messages]( with % placeholders. The hope here is that it's much cleaner and more intuitive to match using the syntax used for log message placeholders. (Similar to how printf and scanf pair nicely).

from logot import logged

logot.wait_for(logged.info("Hello %s"))

But loguru uses lovely .format()-style placeholders!

Maybe it's fine to just use % placeholders in loguru tests? 🤷

But it might be nice to support .format()-style placeholders like this:

from logot.contrib.loguru import logged

logot.wait_for(logged.info("Hello {}"))

Support for matching structured data would also be possible:

logot.wait_for(
    logged.bind(foo="bar").info("Hello {}")
)

hashtaghashtag Advice appreciated! 🙏

Thanks for reading this far!

I'm inclined to go with a LoguruCapture backend combined with .format()-style message matching. That would give first-class support for loguru without compromising or complicating the stdlib interface.

However, I'm not really familiar with the loguru community and ecosystem! Maybe this is unappealing? Maybe it's already been done! 😬

Hope you have a nice weekend! ❤️ )

[mayil-ai[bot]]

Based on the ticket description, here are the recommendations for integrating logot with loguru:

• Log Capture:

  • Implement a LoguruCapture backend as a capturing mechanism for loguru. This aligns with the existing design pattern for logot and provides a unified approach for capturing logs from both stdlib logging and loguru.
  • Ensure that any arguments given to capturing are propagated to the LoguruCapture constructor to maintain flexibility and configurability.

• Log Message Matching:

  • Support .format()-style placeholders in logot to match loguru's logging style. This will provide a more intuitive experience for users familiar with loguru.
  • Implement structured data matching to allow users to match logs with bound context variables, enhancing the testing capabilities for structured logging.

• Integration Approach:

  • Avoid creating a separate Logot subclass for loguru as it would be heavyweight and less elegant.
  • Instead, extend logot to support loguru as a first-class citizen through the LoguruCapture backend and .format()-style message matching.

Here is a high-level overview of the proposed changes in pseudo-code:

# logot/contrib/loguru.py

from loguru import logger
from logot import Logot

class LoguruCapture:
    def __init__(self, *args, **kwargs):
        # Initialize with any arguments passed to capturing
        pass

    def start_capture(self):
        # Logic to start capturing logs from loguru
        pass

    def stop_capture(self):
        # Logic to stop capturing logs from loguru
        pass

    def get_captured_logs(self):
        # Logic to retrieve captured logs
        pass

# Extend Logot to use LoguruCapture as a backend for capturing
class LogotWithLoguru(Logot):
    def capturing(self, backend=LoguruCapture):
        # Override capturing method to use LoguruCapture
        pass

# Extend the logged function to support .format() style placeholders
def logged(level, message):
    # Convert .format() style placeholders to % placeholders if necessary
    # Match the log message with the placeholders
    pass

# Example usage
with LogotWithLoguru().capturing() as logot:
    logger.info("Test log message with {}", "loguru")
    logot.wait_for(logged.info("Test log message with {}"))

This approach should provide a clean and efficient integration between logot and loguru, offering users the ability to test loguru-based logging with the same ease and flexibility as stdlib logging.