several updates to functionality

tests/test_uid_mapping.py

@@ -0,0 +1,27 @@
+import unittest
+
+from validation import validate_uid_mapping
+
+
+class UidMappingTest(unittest.TestCase):
+    def test_ambiguous_mapping_requires_ids(self) -> None:
+        events = [
+            {"title": "Event A"},
+            {"title": "Event B"},
+        ]
+
+        with self.assertRaises(ValueError) as ctx:
+            validate_uid_mapping(events, {"Event A"}, {2})
+
+        message = str(ctx.exception)
+        self.assertIn("Ambivalent UID-mapping", message)
+        self.assertIn("events[].id", message)
+
+    def test_ambiguous_mapping_with_ids_returns_false(self) -> None:
+        events = [
+            {"id": "log_01", "title": "Event A"},
+            {"id": "log_02", "title": "Event B"},
+        ]
+
+        allow = validate_uid_mapping(events, {"Event A"}, {2})
+        self.assertFalse(allow)