Fix unit tests.

Author: WaVEV

tests/atlas_search_/test_search.py

@@ -685,10 +685,10 @@ def test_str_returns_expected_format(self):
         )
 
 
-@unittest.expectedFailure(
-    "Cannot find a match for the provided reference documents in Atlas Search"
-)
+@unittest.expectedFailure
 class SearchMoreLikeThisTests(SearchUtilsMixin):
+    """Expected failure: Cannot find a matching document in search index."""
+
     @classmethod
     def setUpClass(cls):
         super().setUpClass()