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fix(brother-ql): doppelter 'preflight SNMP failed' Prefix vermieden #114

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Merged
strausmann merged 1 commit into from
Jun 9, 2026
Merged

fix(brother-ql): doppelter 'preflight SNMP failed' Prefix vermieden #114

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7 changes: 6 additions & 1 deletion backend/app/printer_backends/brother_ql_backend.py
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Original file line number Diff line number Diff line change
Expand Up @@ -173,7 +173,12 @@ async def preflight_check(
timeout_s=timeout_s,
)
except SnmpQueryError as exc:
raise PrinterOfflineError(f"preflight SNMP failed: {exc}") from exc
# Issue #105: query_preflight() kann bereits "preflight SNMP failed: …"
# im SnmpQueryError enthalten — doppeltes Prefixen vermeiden.
msg = str(exc)
if not msg.startswith("preflight SNMP failed:"):
msg = f"preflight SNMP failed: {msg}"
raise PrinterOfflineError(msg) from exc
Comment on lines +178 to +181

@gemini-code-assist gemini-code-assist Bot Jun 9, 2026

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medium

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


if "noPaper" in preflight.error_flags:
raise TapeEmptyError()
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34 changes: 34 additions & 0 deletions backend/tests/unit/printer_backends/test_brother_ql_backend.py
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Original file line number Diff line number Diff line change
Expand Up @@ -179,3 +179,37 @@ async def fake_preflight(
backend = BrotherQLBackend(host="unreachable", model_id="QL-820NWB")
with pytest.raises(PrinterOfflineError, match="preflight SNMP failed"):
await backend.preflight_check()


@pytest.mark.anyio
async def test_preflight_check_no_duplicate_prefix_when_snmp_error_already_has_prefix(
monkeypatch: pytest.MonkeyPatch,
) -> None:
"""Issue #105: PrinterOfflineError darf 'preflight SNMP failed' nicht doppelt enthalten.

query_preflight() erzeugt SnmpQueryError-Messages die bereits mit
'preflight SNMP failed: ' beginnen (snmp_helper.py Zeile 191).
Das BrotherQLBackend darf dann den Prefix NICHT nochmal voranstellen.
"""
from app.printer_backends.exceptions import PrinterOfflineError
from app.printer_backends.snmp_helper import PreflightStatus, SnmpQueryError

# Simuliert was snmp_helper.query_preflight() bei SNMP-Fehler wirft —
# die Message beginnt bereits mit "preflight SNMP failed: ".
already_prefixed_msg = "preflight SNMP failed: UDP transport error"

async def fake_preflight(
host: str, *, community: str = "public", timeout_s: float = 3.0
) -> PreflightStatus:
raise SnmpQueryError(already_prefixed_msg)

monkeypatch.setattr("app.printer_backends.brother_ql_backend.query_preflight", fake_preflight)
backend = BrotherQLBackend(host="unreachable", model_id="QL-820NWB")
with pytest.raises(PrinterOfflineError) as exc_info:
await backend.preflight_check()

error_msg = str(exc_info.value)
# Darf nur EINMAL "preflight SNMP failed" enthalten
assert error_msg.count("preflight SNMP failed") == 1, (
f"Duplicate prefix in error message: {error_msg!r}"
)
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