Make autocomplete() fail with a NotImplementedError on sqlite and mysql FTS backends

wagtail/search/backends/database/mysql/mysql.py

@@ -633,7 +633,11 @@ class MySQLSearchAtomicRebuilder(MySQLSearchRebuilder):
 
 class MySQLSearchBackend(BaseSearchBackend):
     query_compiler_class = MySQLSearchQueryCompiler
-    autocomplete_query_compiler_class = MySQLAutocompleteQueryCompiler
+
+    # FIXME: the implementation of MySQLAutocompleteQueryCompiler is incomplete -
+    # leave this undefined so that we get a clean NotImplementedError from BaseSearchBackend
+    # autocomplete_query_compiler_class = MySQLAutocompleteQueryCompiler
+
     results_class = MySQLSearchResults
     rebuilder_class = MySQLSearchRebuilder
     atomic_rebuilder_class = MySQLSearchAtomicRebuilder

wagtail/search/backends/database/sqlite/sqlite.py

@@ -650,7 +650,11 @@ class SQLiteSearchResults(BaseSearchResults):
 
 class SQLiteSearchBackend(BaseSearchBackend):
     query_compiler_class = SQLiteSearchQueryCompiler
-    autocomplete_query_compiler_class = SQLiteAutocompleteQueryCompiler
+
+    # FIXME: the implementation of SQLiteAutocompleteQueryCompiler is incomplete -
+    # leave this undefined so that we get a clean NotImplementedError from BaseSearchBackend
+    # autocomplete_query_compiler_class = SQLiteAutocompleteQueryCompiler
+
     results_class = SQLiteSearchResults
     rebuilder_class = SQLiteSearchRebuilder
     atomic_rebuilder_class = SQLiteSearchAtomicRebuilder

wagtail/search/tests/test_mysql_backend.py

@@ -90,6 +90,10 @@ class TestMySQLSearchBackend(BackendTests, TransactionTestCase):
     def test_annotate_score_with_slice(self):
         return super().test_annotate_score_with_slice()
 
+    def test_autocomplete_raises_not_implemented_error(self):
+        with self.assertRaises(NotImplementedError):
+            self.backend.autocomplete("Py", models.Book)
+
     @skip("The MySQL backend doesn't support autocomplete.")
     def test_autocomplete(self):
         return super().test_autocomplete()

wagtail/search/tests/test_sqlite_backend.py

@@ -8,6 +8,7 @@ from django.test.utils import override_settings
 
 from wagtail.search.backends.database.sqlite.utils import fts5_available
 from wagtail.search.tests.test_backends import BackendTests
+from wagtail.test.search import models
 
 
 @unittest.skipUnless(
@@ -43,6 +44,10 @@ class TestSQLiteSearchBackend(BackendTests, TestCase):
     def test_annotate_score_with_slice(self):
         return super().test_annotate_score_with_slice()
 
+    def test_autocomplete_raises_not_implemented_error(self):
+        with self.assertRaises(NotImplementedError):
+            self.backend.autocomplete("Py", models.Book)
+
     @skip("The SQLite backend doesn't support autocomplete.")
     def test_autocomplete(self):
         return super().test_autocomplete()