fix(brother-ql): doppelter 'preflight SNMP failed' Prefix vermieden

[strausmann]

Summary

• Behebt doppelten preflight SNMP failed Prefix in PrinterOfflineError Messages
• query_preflight() in snmp_helper.py wirft bereits SnmpQueryError("preflight SNMP failed: …") — BrotherQLBackend hat denselben Prefix nochmal hinzugefügt
• Fix prüft ob Prefix bereits vorhanden, bevor er vorangestellt wird

Closes #105

Test plan

• Neuer Test test_preflight_check_no_duplicate_prefix_when_snmp_error_already_has_prefix schlägt vor dem Fix fehl (TDD Red → bestätigt Bug)
• Test grün nach Fix (TDD Green)
• Bestehende Tests test_preflight_check_raises_offline_on_snmp_error und alle anderen weiterhin grün
• Alle 733 Unit-Tests grün

🤖 Generated with Claude Code

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

Diese Pull Request behebt ein Problem, bei dem Fehlermeldungen des BrotherQLBackend redundant formatiert wurden. Durch die Überprüfung des bestehenden Fehler-Strings wird sichergestellt, dass das Präfix 'preflight SNMP failed' nur einmalig in der finalen Exception erscheint, was die Lesbarkeit der Logs verbessert.

Highlights

• Fehlerbehebung bei Fehlermeldungen: Verhindert die doppelte Präfixierung von 'preflight SNMP failed' in PrinterOfflineError-Meldungen.
• Implementierung einer Prüfung: Der Code prüft nun, ob der Fehler-String bereits das Präfix enthält, bevor es erneut hinzugefügt wird.
• Erweiterte Testabdeckung: Ein neuer Unit-Test wurde hinzugefügt, um sicherzustellen, dass das Präfix bei SnmpQueryError nicht dupliziert wird.

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[gemini-code-assist]

Code Review

This pull request addresses Issue #105 by preventing duplicate 'preflight SNMP failed' prefixes in PrinterOfflineError messages when handling SnmpQueryError in the Brother QL backend, and adds a corresponding unit test. The review feedback suggests a more robust prefix check (checking for 'preflight SNMP' instead of 'preflight SNMP failed:') to handle other potential error message variations and avoid duplicate prefixes.

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[gemini-code-assist]

Wenn query_preflight() einen SnmpQueryError mit einer Nachricht wie "preflight SNMP returned error: ..." wirft, startet diese nicht mit "preflight SNMP failed:". Dadurch wird die Fehlermeldung zu "preflight SNMP failed: preflight SNMP returned error: ..." formatiert, was ein doppeltes "preflight SNMP"-Präfix erzeugt.

Eine robustere Prüfung wäre es, auf "preflight SNMP" zu prüfen, um jegliche doppelte Präfixe für alle von query_preflight() geworfenen Fehler zu vermeiden.

Suggested change

	msg = str(exc)
	if not msg.startswith("preflight SNMP failed:"):
	msg = f"preflight SNMP failed: {msg}"
	raise PrinterOfflineError(msg) from exc
	msg = str(exc)
	if not msg.startswith("preflight SNMP"):
	msg = f"preflight SNMP failed: {msg}"
	raise PrinterOfflineError(msg) from exc

[Copilot]

Pull request overview

Diese Änderung behebt ein kosmetisches Problem in der Fehlerbehandlung des BrotherQLBackend: Wenn query_preflight() bereits eine SnmpQueryError-Message mit dem Prefix preflight SNMP failed: liefert, soll BrotherQLBackend.preflight_check() diesen Prefix nicht nochmals voranstellen (verhindert Meldungen wie preflight SNMP failed: preflight SNMP failed: …). Das passt zur in Issue #105 beschriebenen Phase-1j-Qualitätsbereinigung.

Changes:

• Entdoppelt den preflight SNMP failed: Prefix in BrotherQLBackend.preflight_check() durch eine startswith(...)-Prüfung.
• Fügt einen Unit-Test hinzu, der den Doppel-Prefix-Fall reproduziert und sicherstellt, dass die Message den Prefix nur einmal enthält.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
backend/app/printer_backends/brother_ql_backend.py	Verhindert doppeltes Prefixing der PrinterOfflineError-Message bei bereits präfixierten SnmpQueryErrors.
backend/tests/unit/printer_backends/test_brother_ql_backend.py	Ergänzt einen Regressionstest für den bereits-präfixierten SNMP-Fehlerfall (Issue #105).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.21%. Comparing base (ddcf114) to head (f5edd6d).
⚠️ Report is 5 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #114      +/-   ##
==========================================
+ Coverage   89.18%   89.21%   +0.03%     
==========================================
  Files          91       91              
  Lines        4243     4246       +3     
  Branches      365      366       +1     
==========================================
+ Hits         3784     3788       +4     
  Misses        360      360              
+ Partials       99       98       -1     

Components	Coverage Δ
Printer Backends (transport)	86.87% <100.00%> (+0.11%)	⬆️
Printer Models (drivers)	88.20% <ø> (ø)
Services	91.17% <ø> (+0.07%)	⬆️
REST API	84.97% <ø> (ø)
Pydantic Schemas	100.00% <ø> (ø)
Integration Plugins	100.00% <ø> (ø)

Files with missing lines	Coverage Δ
backend/app/printer_backends/brother_ql_backend.py	88.00% <100.00%> (+0.76%)	⬆️

... and 1 file with indirect coverage changes

Flag	Coverage Δ
backend	89.21% <100.00%> (+0.03%)	⬆️

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