Proposal: disable "live logging" by default and write to terminal writer instead

The Live Logs feature currently is enabled by default and requires the user to pass -s to see the logs.

I see two problems:

1. If the user is interested in the feature, having to pass -s feels clumsy because now all sort of outputs will come through, reducing the actual usefulness of the feature because it will be harder to see the actual logging messages.
2. To solve 1), I believe we will need to write to the TerminalWriter, which by consequence will show up for all users from that point on even if they are not interested in the feature because the default is WARNING.

My proposal:

1. Create a new property, live_logs, defaulting to False.
2. Write the “live logs” to the TerminalWriter, probably in color according to the level, yellow for WARNING and red for CRITICAL. This means users won’t need to use -s to see live logs anymore.

This feature was originally implemented in eisensheng/pytest-catchlog#33 but was never released to PyPI, so I assume “live logs” has seen little use in the wild.

cc @thisch

[nicoddemus]

Finally got time to work on this proposal, #3124 is open and all comments are welcome.

[ederag]

@nicoddemus Yes, it is a different use case, not related to pytest. The application uses the python logger with a basic logging.StreamHandler() that outputs to stderr. For this app, it is currently the main feedback mechanism to the user. In this case, --no-print-logs is preferable.

logging is not configured by Python by default, perhaps pytest should follow the same logic

Exactly, the application logger level should not be tampered with during the tests, unless explicitly requested. (otherwise, how to check that the default logging level of the app is correct ?)