Fix #3297 where caplog.clear() did not clear text, just records

[ankostis]

Fix #3297 where caplog.clear() did not clear text, just records.
Fix by @Thisch that re-installs a new StringIO on the handler as suggested in https://stackoverflow.com/questions/4330812/how-do-i-clear-a-stringio-object#4330829

• Actually work delegated to a new reset() method on the handler, used also on caplog construction .
• Added TC demonstrating failure.

[coveralls]

Coverage increased (+0.06%) to 92.6% when pulling 02bec7a on ankostis:caplog_clear_text into 3909225 on pytest-dev:master.

[nicoddemus]

Thanks a lot @ankostis!

The only thing missing is a changelog entry, please create a file named changelog/3297.bugfix.rst describing this change, I suggest:

``caplog.clear`` now also properly clears the ``text`` property.

[nicoddemus]

For consistency perhaps we should call this clear too?

[ankostis]

But i see that there pre-existed also _LiveLoggingStreamHandler.reset() method,
so maybe @Thisch had a reason to use this name.

[nicoddemus]

Oh I didn't notice that, never mind then.

[twmr]

Note that the docstring of LogCaptureFixure.clear starts with "reset" ;) There is no specific reson why I chose "reset" in my initial commit, though.

[ankostis]

I didn't see any other files in changelog/ so i hesitated to add this.
I've re-written last commit, and hope this is what you asked.

[nicoddemus]

I didn't see any other files in changelog/ so i hesitated to add this.
I've re-written last commit, and hope this is what you asked.

Yep is just that we just had a release last week and your PR is the first one since then to land on master. 👍

Thanks, LGTM! 👍

[RonnyPfannschmidt]

👍 thanks