Log a warning for uncommitted changes on transaction exit

[maxmynter]

Closes #264

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f05c5b6) 94.24% compared to head (c599118) 94.32%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #266      +/-   ##
==========================================
+ Coverage   94.24%   94.32%   +0.08%     
==========================================
  Files           5        5              
  Lines         382      388       +6     
  Branches       70       72       +2     
==========================================
+ Hits          360      366       +6     
  Misses         13       13              
  Partials        9        9              

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[nicholasjng]

Suggested change

	if any(True for _ in self._ephemeral_branch.uncommitted()):
	logger.warning(
	f"Transaction closed with uncommitted changes. {'Objects added but not committed are lost.' if self.delete != 'never' else ''}"
	)
	if any(self._ephemeral_branch.uncommitted()):
	msg = f"Finished transaction {self._ephemeral_branch.id!r} contains uncommitted changes."
	if self.delete != "never":
	msg += " Objects added but not committed are lost."
	warnings.warn(msg)

Explanation: We always prefer a warning over a log, because that works even when the user does not set up logging. If the user needs logging, he can do import logging; logging.capturewarnings(True), if he wants to catch the warnings, he can do so with a warnings filter context manager or by redirecting stderr.

Bonus: We keep a clean separation between stdout and stderr.

[nicholasjng]

Nice work!