refactor: centralize numeric normalization

tests/test_numeric_normalization.py

@@ -0,0 +1,38 @@
+from __future__ import annotations
+
+import math
+import unittest
+
+from backend.data.numbers import finite_number, non_nan_number
+from backend.data.providers import tushare_client
+from backend.features.market import insights
+from backend.features.screener import engine as screener_engine
+from backend.features.sentiment import engine as sentiment_engine
+
+
+class NumericNormalizationTests(unittest.TestCase):
+    def test_consumers_use_their_declared_shared_policy(self) -> None:
+        self.assertIs(tushare_client._number, finite_number)
+        self.assertIs(screener_engine._number, finite_number)
+        self.assertIs(insights._number, non_nan_number)
+        self.assertIs(sentiment_engine._number, non_nan_number)
+
+    def test_finite_policy_preserves_existing_results(self) -> None:
+        self.assertEqual(finite_number("12.5"), 12.5)
+        self.assertEqual(finite_number(None), 0.0)
+        self.assertEqual(finite_number("invalid", 7.0), 7.0)
+        self.assertEqual(finite_number(math.nan, 7.0), 7.0)
+        self.assertEqual(finite_number(math.inf, 7.0), 7.0)
+        self.assertEqual(finite_number(-math.inf, 7.0), 7.0)
+
+    def test_non_nan_policy_keeps_infinity_but_rejects_nan(self) -> None:
+        self.assertEqual(non_nan_number("12.5"), 12.5)
+        self.assertEqual(non_nan_number(None), 0.0)
+        self.assertEqual(non_nan_number("invalid", 7.0), 7.0)
+        self.assertEqual(non_nan_number(math.nan, 7.0), 7.0)
+        self.assertEqual(non_nan_number(math.inf, 7.0), math.inf)
+        self.assertEqual(non_nan_number(-math.inf, 7.0), -math.inf)
+
+
+if __name__ == "__main__":
+    unittest.main()