✨(backend) add fallback search & default ordering

Filter deleted documents from visited ones.
Set default ordering to the Find API search call (-updated_at)
BaseDocumentIndexer.search now returns a list of document ids instead of models.
Do not call the indexer in signals when SEARCH_INDEXER_CLASS is not defined
or properly configured.

Signed-off-by: Fabre Florian <ffabre@hybird.org>

src/backend/core/tests/conftest.py

@@ -24,3 +24,32 @@ def mock_user_teams():
         "core.models.User.teams", new_callable=mock.PropertyMock
     ) as mock_teams:
         yield mock_teams
+
+
+@pytest.fixture(name="indexer_settings")
+def indexer_settings_fixture(settings):
+    """
+    Setup valid settings for the document indexer. Clear the indexer cache.
+    """
+
+    # pylint: disable-next=import-outside-toplevel
+    from core.services.search_indexers import (  # noqa: PLC0415
+        default_document_indexer,
+        get_document_indexer_class,
+    )
+
+    default_document_indexer.cache_clear()
+    get_document_indexer_class.cache_clear()
+
+    settings.SEARCH_INDEXER_CLASS = "core.services.search_indexers.FindDocumentIndexer"
+    settings.SEARCH_INDEXER_SECRET = "ThisIsAKeyForTest"
+    settings.SEARCH_INDEXER_URL = "http://localhost:8081/api/v1.0/documents/index/"
+    settings.SEARCH_INDEXER_QUERY_URL = (
+        "http://localhost:8081/api/v1.0/documents/search/"
+    )
+
+    yield settings
+
+    # clear cache to prevent issues with other tests
+    default_document_indexer.cache_clear()
+    get_document_indexer_class.cache_clear()