fix(salary): validate metadata before rendering lookups (#575)

* fix(salary): validate metadata before rendering lookups

* docs(changelog): record fix for #575

tests/test_salary_metadata_cli.py

@@ -0,0 +1,60 @@
+"""The documented pre-flight must reject metadata that breaks table lookups."""
+import json
+import shutil
+import subprocess
+import sys
+import unittest
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+TOOL = Path(__file__).resolve().parent.parent / "salary_lookup.py"
+
+
+class SalaryMetadataCLI(unittest.TestCase):
+    def run_lookup(self, metadata, *args):
+        with TemporaryDirectory() as directory:
+            root = Path(directory)
+            shutil.copyfile(TOOL, root / TOOL.name)
+            (root / "salary_data.json").write_text(json.dumps({
+                "metadata": metadata,
+                "companies": [{"company": "Acme", "categories": {"all_employees": {"index": 165}}}],
+            }), encoding="utf-8")
+            return subprocess.run(
+                [sys.executable, str(root / TOOL.name), *args],
+                capture_output=True, text=True, encoding="utf-8",
+            )
+
+    def test_preflight_rejects_a_text_baseline(self):
+        result = self.run_lookup({"index_baseline": "150"}, "--validate")
+        self.assertEqual(result.returncode, 1, result.stdout + result.stderr)
+        self.assertIn("index_baseline", result.stdout + result.stderr)
+
+    def test_lookup_rejects_a_text_baseline_without_a_traceback(self):
+        result = self.run_lookup({"index_baseline": "150"}, "Acme")
+        self.assertEqual(result.returncode, 1)
+        self.assertIn("index_baseline", result.stderr)
+        self.assertNotIn("Traceback", result.stderr)
+
+    def test_preflight_rejects_a_non_text_index_label(self):
+        result = self.run_lookup({"index_label": ["Salary"]}, "--validate")
+        self.assertEqual(result.returncode, 1, result.stdout + result.stderr)
+        self.assertIn("index_label", result.stdout + result.stderr)
+
+    def test_preflight_rejects_unusable_numeric_baselines(self):
+        for baseline in [True, None, float("inf"), float("nan"), 10 ** 400]:
+            with self.subTest(baseline=baseline):
+                result = self.run_lookup({"index_baseline": baseline}, "--validate")
+                self.assertEqual(result.returncode, 1, result.stdout + result.stderr)
+                self.assertIn("index_baseline", result.stdout + result.stderr)
+                self.assertNotIn("Traceback", result.stderr)
+
+    def test_numeric_baseline_and_optional_metadata_controls(self):
+        for metadata, percentage in [({"index_baseline": 150, "index_label": "Salary"}, "+10.0%"),
+                                     ({"index_baseline": 0}, None), ({}, "+65.0%"), (None, "+65.0%")]:
+            with self.subTest(metadata=metadata):
+                result = self.run_lookup(metadata, "Acme")
+                self.assertEqual(result.returncode, 0, result.stderr)
+                if percentage:
+                    self.assertIn(percentage, result.stdout)
+                else:
+                    self.assertNotIn("%", result.stdout)