feat(okf): add okf_common frontmatter/link parser with tests

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

custom-skills/97-ourdigital-okf/code/scripts/tests/test_okf_common.py

@@ -0,0 +1,47 @@
+import sys, unittest
+from pathlib import Path
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+from okf_common import (parse_frontmatter, parse_yaml_subset,
+                        extract_links, concept_id, FrontmatterError)
+
+
+class TestFrontmatter(unittest.TestCase):
+    def test_parse_basic(self):
+        text = "---\ntype: BigQuery Table\ntitle: Orders\ntags: [sales, revenue]\n---\n\n# Body\n"
+        meta, body = parse_frontmatter(text)
+        self.assertEqual(meta["type"], "BigQuery Table")
+        self.assertEqual(meta["title"], "Orders")
+        self.assertEqual(meta["tags"], ["sales", "revenue"])
+        self.assertIn("# Body", body)
+
+    def test_url_value_with_colons(self):
+        meta, _ = parse_frontmatter("---\ntype: X\nresource: https://e.com/a?b=c\n---\nbody")
+        self.assertEqual(meta["resource"], "https://e.com/a?b=c")
+
+    def test_quoted_value(self):
+        self.assertEqual(parse_yaml_subset('okf_version: "0.1"')["okf_version"], "0.1")
+
+    def test_empty_list(self):
+        self.assertEqual(parse_yaml_subset("tags: []")["tags"], [])
+
+    def test_no_frontmatter(self):
+        meta, body = parse_frontmatter("# Just markdown\n")
+        self.assertIsNone(meta)
+        self.assertEqual(body, "# Just markdown\n")
+
+    def test_unclosed_raises(self):
+        with self.assertRaises(FrontmatterError):
+            parse_frontmatter("---\ntype: X\n\nbody without close")
+
+
+class TestLinksAndIds(unittest.TestCase):
+    def test_extract_links(self):
+        body = "See [a](/tables/a.md) and [b](./b.md) and [ext](https://x.com)."
+        self.assertEqual(extract_links(body), ["/tables/a.md", "./b.md", "https://x.com"])
+
+    def test_concept_id(self):
+        self.assertEqual(concept_id("/bundle", "/bundle/tables/users.md"), "tables/users")
+
+
+if __name__ == "__main__":
+    unittest.main()