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fix: interpret naive detected_at as UTC when rendering alert timestamps #2305

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fix: interpret naive detected_at as UTC when rendering alert timestamps #2305

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6 changes: 5 additions & 1 deletion elementary/monitor/alerts/alert.py
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Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,11 @@ def __init__(
self.detected_at = None
if detected_at is not None:
try:
self.detected_at_utc = detected_at
# detected_at is stored in UTC, so a naive datetime must be
# interpreted as UTC rather than as the machine's local time.
if detected_at.tzinfo is None:
detected_at = detected_at.replace(tzinfo=tz.tzutc())
self.detected_at_utc = detected_at.astimezone(tz.tzutc())
self.detected_at = detected_at.astimezone(
tz.gettz(timezone) if timezone else tz.tzlocal()
Comment on lines +61 to 67

@coderabbitai coderabbitai Bot Jul 23, 2026

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🩺 Stability & Availability | 🟠 Major | ⚡ Quick win

Avoid mixing normalized timestamps with the group’s naive fallback.

After this change, a naive input produces an aware self.detected_at, but base_alerts_group.py:22-23 still evaluates min(alert.detected_at or datetime.max ...). A group containing one normalized alert and one missing timestamp now raises TypeError: can't compare offset-naive and offset-aware datetimes. Make that fallback timezone-aware (or exclude missing timestamps before min()) and add a mixed-group regression test.

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@elementary/monitor/alerts/alert.py` around lines 61 - 67, Update the group
timestamp calculation in the logic containing min(alert.detected_at or
datetime.max ...) so missing timestamps use a timezone-aware UTC fallback, or
are excluded before computing min, preventing comparisons between naive and
aware datetimes. Preserve the existing behavior for present timestamps and add a
regression test covering a group with one normalized alert and one missing
timestamp.

)
Expand Down
85 changes: 85 additions & 0 deletions tests/unit/monitor/alerts/test_alert_models.py
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Original file line number Diff line number Diff line change
@@ -1,11 +1,24 @@
import time
from datetime import datetime

import pytest
from dateutil import tz

from elementary.monitor.alerts.alert import AlertModel
from elementary.monitor.alerts.model_alert import ModelAlertModel
from elementary.monitor.alerts.source_freshness_alert import SourceFreshnessAlertModel
from elementary.monitor.alerts.test_alert import TestAlertModel


@pytest.fixture
def tokyo_local_timezone(monkeypatch):
monkeypatch.setenv("TZ", "Asia/Tokyo")
time.tzset()
yield
monkeypatch.undo()
time.tzset()


def _make_test_alert(
test_sub_type: str = "generic", test_short_name: str = "my_test"
) -> TestAlertModel:
Expand Down Expand Up @@ -95,3 +108,75 @@ def test_asset_type_is_source(self) -> None:
def test_concise_name_is_source_dot_identifier(self) -> None:
alert = _make_source_freshness_alert(source_name="raw", identifier="orders")
assert alert.concise_name == "raw.orders"


class TestAlertModelDetectedAtTimezone:
"""detected_at is stored in UTC (naive) in the alerts table and must be
interpreted as UTC, not as the machine's local time."""

def test_naive_detected_at_is_converted_to_given_timezone(
self, tokyo_local_timezone
) -> None:
alert = AlertModel(
id="id",
alert_class_id="acid",
detected_at=datetime(2026, 7, 22, 9, 8, 22),
timezone="Asia/Tokyo",
)
assert alert.detected_at == datetime(
2026, 7, 22, 18, 8, 22, tzinfo=tz.gettz("Asia/Tokyo")
)
assert alert.detected_at_str == "2026-07-22 18:08:22 JST"

def test_naive_detected_at_is_converted_to_local_timezone_by_default(
self, tokyo_local_timezone
) -> None:
alert = AlertModel(
id="id",
alert_class_id="acid",
detected_at=datetime(2026, 7, 22, 9, 8, 22),
)
assert alert.detected_at_str == "2026-07-22 18:08:22 JST"

def test_naive_detected_at_utc_is_utc_aware(self, tokyo_local_timezone) -> None:
alert = AlertModel(
id="id",
alert_class_id="acid",
detected_at=datetime(2026, 7, 22, 9, 8, 22),
timezone="Asia/Tokyo",
)
assert alert.detected_at_utc == datetime(
2026, 7, 22, 9, 8, 22, tzinfo=tz.tzutc()
)

def test_aware_detected_at_keeps_working(self, tokyo_local_timezone) -> None:
alert = AlertModel(
id="id",
alert_class_id="acid",
detected_at=datetime(2026, 7, 22, 9, 8, 22, tzinfo=tz.tzutc()),
timezone="Asia/Tokyo",
)
assert alert.detected_at_str == "2026-07-22 18:08:22 JST"

def test_source_freshness_result_description_uses_consistent_timezone(
self, tokyo_local_timezone
) -> None:
alert = SourceFreshnessAlertModel(
id="id",
source_name="my_source",
identifier="my_table",
original_status="fail",
path="models/src.yml",
error=None,
alert_class_id="acid",
source_freshness_execution_id="sfeid",
detected_at=datetime(2026, 7, 22, 9, 8, 22),
max_loaded_at=datetime(2026, 7, 21, 8, 55, 10),
max_loaded_at_time_ago_in_s=87101.8,
timezone="Asia/Tokyo",
)
assert alert.result_description == (
"When the test ran at 2026-07-22 18:08:22 JST, "
"the most recent record found in the table was 1 day 0h 11m 41s earlier "
"(2026-07-21 17:55:10 JST)."
)
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