style: auto-fix lint violations from enhanced ruff rules

1 files changed, 4 insertions, 5 deletions

diff --git a/services/backtester/tests/test_metrics.py b/services/backtester/tests/test_metrics.py
index 55f5b6c..13e545e 100644
--- a/services/backtester/tests/test_metrics.py
+++ b/services/backtester/tests/test_metrics.py
@@ -1,17 +1,16 @@
 """Tests for detailed backtest metrics."""
 
 import math
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 from decimal import Decimal
 
 import pytest
-
 from backtester.metrics import TradeRecord, compute_detailed_metrics
 
 
 def _make_trade(side: str, price: str, minutes_offset: int = 0) -> TradeRecord:
     return TradeRecord(
-        time=datetime(2025, 1, 1, tzinfo=timezone.utc) + timedelta(minutes=minutes_offset),
+        time=datetime(2025, 1, 1, tzinfo=UTC) + timedelta(minutes=minutes_offset),
         symbol="AAPL",
         side=side,
         price=Decimal(price),
@@ -124,7 +123,7 @@ def test_consecutive_losses():
 
 def test_risk_free_rate_affects_sharpe():
     """Higher risk-free rate should lower Sharpe ratio."""
-    base = datetime(2025, 1, 1, tzinfo=timezone.utc)
+    base = datetime(2025, 1, 1, tzinfo=UTC)
     trades = [
         TradeRecord(
             time=base, symbol="AAPL", side="BUY", price=Decimal("100"), quantity=Decimal("1")
@@ -184,7 +183,7 @@ def test_daily_returns_populated():
 
 def test_fee_subtracted_from_pnl():
     """Fees should be subtracted from trade PnL."""
-    base = datetime(2025, 1, 1, tzinfo=timezone.utc)
+    base = datetime(2025, 1, 1, tzinfo=UTC)
     trades_with_fees = [
         TradeRecord(
             time=base,