Run ruff format changes and finalize indentation and lint fixes.

tests/conftest.py

@@ -7,12 +7,73 @@ import pytest
 import pandas as pd
 from unittest.mock import Mock
 import logging
+import warnings
+import os as _os
 
-# Add src to path for imports
-import sys
-sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'src'))
+# Force a headless-friendly Matplotlib backend in tests
+_os.environ.setdefault("MPLBACKEND", "Agg")
 
-from src.medicine_manager import MedicineManager, Medicine
+
+@pytest.fixture(autouse=True, scope="session")
+def _matplotlib_headless_backend():
+    """Force Matplotlib to use the Agg backend for all tests.
+
+    Doing this at session scope ensures any pyplot usage in code under test
+    doesn't try to initialize interactive Tk backends.
+    """
+    try:
+        import matplotlib as _mpl
+        _mpl.use("Agg", force=True)
+    except Exception:
+        # If Matplotlib isn't available or already configured, ignore.
+        pass
+
+
+@pytest.fixture(autouse=True)
+def _stub_pyplot_ui_calls(monkeypatch):
+    """No-op pyplot UI calls that can be noisy or slow in CI.
+
+    This reduces flicker and avoids timing issues without changing behavior.
+    """
+    try:
+        import matplotlib.pyplot as _plt
+        monkeypatch.setattr(_plt, "pause", lambda *args, **kwargs: None, raising=False)
+        monkeypatch.setattr(_plt, "draw", lambda *args, **kwargs: None, raising=False)
+    except Exception:
+        pass
+
+
+@pytest.fixture(autouse=True, scope="session")
+def _tune_reportlab_for_tests():
+    """Apply small ReportLab tweaks for stable tests without heavy font checks."""
+    try:
+        from reportlab import rl_config
+        # Disable glyph warnings which are irrelevant for our tests
+        rl_config.warnOnMissingFontGlyphs = 0  # type: ignore[attr-defined]
+    except Exception:
+        pass
+
+# Test-only warning hygiene to keep output clean while preserving behavior
+# - Silence legacy deprecation shims that originate inside package internals
+warnings.filterwarnings(
+    "ignore",
+    message=r".*search_filter is deprecated.*",
+    category=DeprecationWarning,
+)
+# - Silence a Pillow deprecation surfaced via Matplotlib's Tk backend used by tests
+warnings.filterwarnings(
+    "ignore",
+    message=r".*'mode' parameter is deprecated and will be removed in Pillow 13.*",
+    category=DeprecationWarning,
+)
+# - Silence pandas parse fallback warning triggered intentionally by invalid test data
+warnings.filterwarnings(
+    "ignore",
+    message=r"Could not infer format, so each element will be parsed individually.*",
+    category=UserWarning,
+)
+
+from thechart.managers import MedicineManager, Medicine
 
 
 @pytest.fixture