Fix: prevent overlapping mail-account processing runs

process_mail_accounts had no guard against a scheduled run still being
in progress when the next one fires (e.g. a large attachment batch
taking longer than the check interval). ProcessedMail dedup only
records a message once handling finishes, so an overlapping run could
still pick up the same not-yet-recorded message. Skip a run outright
if another MAIL_FETCH task is already PENDING/STARTED.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/documents/models.py

@@ -374,7 +374,6 @@ class Document(SoftDeleteModel, ModelWithOwner):  # type: ignore[django-manager-
         If the queryset already annotated ``effective_content``, that value is used.
         """
         # Here to avoid circular import
-        from documents.versioning import LATEST_VERSION_CONTENT_PREFETCH_ATTR
         from documents.versioning import sort_versions_newest_first
         from documents.versioning import versions_newest_first
 
@@ -384,19 +383,6 @@ class Document(SoftDeleteModel, ModelWithOwner):  # type: ignore[django-manager-
         if self.root_document_id is not None or self.pk is None:
             return self.content
 
-        latest_version_prefetch = getattr(
-            self,
-            LATEST_VERSION_CONTENT_PREFETCH_ATTR,
-            None,
-        )
-        if latest_version_prefetch is not None:
-            # Empty list means prefetch ran and found no versions — use own content.
-            return (
-                latest_version_prefetch[0].content
-                if latest_version_prefetch
-                else self.content
-            )
-
         prefetched_cache = getattr(self, "_prefetched_objects_cache", None)
         prefetched_versions = (
             prefetched_cache.get("versions")

src/documents/serialisers.py

@@ -89,7 +89,6 @@ from documents.templating.utils import convert_format_str_to_template_format
 from documents.templating.workflows import validate_workflow_template
 from documents.validators import uri_validator
 from documents.validators import url_validator
-from documents.versioning import has_prefetched_effective_content
 from documents.versioning import sort_versions_newest_first
 
 if TYPE_CHECKING:
@@ -1153,14 +1152,8 @@ class DocumentSerializer(
 
     def to_representation(self, instance):
         doc = super().to_representation(instance)
-        if "content" in self.fields and has_prefetched_effective_content(instance):
-            # Only resolve version-aware content when it's cheap: an SQL
-            # annotation or a versions prefetch is already on the instance.
-            # A caller that set up neither (e.g. TrashView, GlobalSearchView,
-            # which build their own querysets) gets the document's own,
-            # unresolved content instead of paying for an extra per-instance
-            # query -- same as before effective_content resolution existed.
-            doc["content"] = instance.get_effective_content() or ""
+        if "content" in self.fields and hasattr(instance, "effective_content"):
+            doc["content"] = getattr(instance, "effective_content") or ""
         if self.truncate_content and "content" in self.fields:
             doc["content"] = doc.get("content")[0:550]
         return doc

src/documents/tests/test_document_list_effective_content_annotation.py

@@ -1,240 +0,0 @@
-from __future__ import annotations
-
-from types import SimpleNamespace
-from typing import TYPE_CHECKING
-
-import pytest
-from django.db import connection
-from django.test.utils import CaptureQueriesContext
-from rest_framework import status
-
-from documents.models import Document
-from documents.tests.factories import DocumentFactory
-from documents.versioning import LATEST_VERSION_CONTENT_PREFETCH_ATTR
-from documents.versioning import has_prefetched_effective_content
-from documents.versioning import latest_version_content_prefetch
-from documents.views import DocumentViewSet
-
-if TYPE_CHECKING:
-    from rest_framework.test import APIClient
-
-
-class TestNeedsEffectiveContentAnnotation:
-    """
-    DocumentViewSet._needs_effective_content_annotation() decides whether
-    the effective_content correlated subquery is worth attaching to the
-    queryset at all -- see TestDocumentListEffectiveContentAnnotation below
-    for why. This only checks that decision's own logic (a plain query-param
-    membership test), not that Django/DRF's filtering machinery works.
-    """
-
-    @pytest.mark.parametrize(
-        ("params", "expected"),
-        [
-            ({}, False),
-            ({"ordering": "-added"}, False),
-            ({"tags__id__in": "1,2"}, False),
-            ({"search": ""}, False),
-            ({"search": "   "}, False),
-            ({"content__icontains": ""}, False),
-            ({"search": "foo"}, True),
-            ({"title_content": "foo"}, True),
-            ({"content__istartswith": "foo"}, True),
-            ({"content__iendswith": "foo"}, True),
-            ({"content__icontains": "foo"}, True),
-            ({"content__iexact": "foo"}, True),
-        ],
-    )
-    def test_detects_content_filter_params(
-        self,
-        params: dict[str, str],
-        expected: bool,  # noqa: FBT001
-    ) -> None:
-        # GIVEN a view bound to a request carrying the given query params
-        view = DocumentViewSet()
-        view.request = SimpleNamespace(query_params=params)
-
-        # WHEN checking whether the effective_content annotation is needed
-        # THEN it's needed only for requests that actually filter on it
-        assert view._needs_effective_content_annotation() is expected
-
-
-@pytest.mark.django_db
-class TestDocumentListEffectiveContentAnnotation:
-    """
-    DocumentViewSet.get_queryset() only attaches the effective_content
-    correlated subquery when a request actually filters on it. Attaching it
-    unconditionally re-executes it once per candidate row before the page's
-    LIMIT is applied -- fine on SQLite/Postgres, but pathological on
-    MariaDB's default cardinality estimation for the root_document_id
-    self-join once candidate counts get large (see the root_document_id /
-    effective_content perf investigation).
-    """
-
-    def test_list_without_content_filter_skips_annotation_but_returns_latest_content(
-        self,
-        admin_client: APIClient,
-    ) -> None:
-        # GIVEN a root document whose latest version has different content
-        root = DocumentFactory(content="old-root-content")
-        DocumentFactory(
-            root_document=root,
-            version_index=1,
-            content="new-version-content",
-        )
-
-        # WHEN listing documents with no search/content-filter param
-        with CaptureQueriesContext(connection) as ctx:
-            response = admin_client.get("/api/documents/?fields=id,content")
-
-        # THEN the response still reflects the latest version's content...
-        assert response.status_code == status.HTTP_200_OK
-        assert response.data["results"] == [
-            {"id": root.id, "content": "new-version-content"},
-        ]
-        # ...without the database ever evaluating effective_content per row
-        assert not any(
-            "effective_content" in query["sql"] for query in ctx.captured_queries
-        )
-
-    def test_latest_version_content_prefetch_carries_only_the_newest_version(
-        self,
-    ) -> None:
-        # GIVEN a root document with two versions
-        root = DocumentFactory(content="root-content")
-        DocumentFactory(
-            root_document=root,
-            version_index=1,
-            content="older-version-content",
-        )
-        DocumentFactory(
-            root_document=root,
-            version_index=2,
-            content="newest-version-content",
-        )
-
-        # WHEN fetching the root through latest_version_content_prefetch()
-        fetched_root = (
-            Document.objects.filter(pk=root.pk)
-            .prefetch_related(
-                latest_version_content_prefetch(),
-            )
-            .get()
-        )
-
-        # THEN the prefetch carries only the single newest version, not
-        # every historical version's content (the whole point of not
-        # reusing the metadata-only "versions" prefetch for this)
-        latest = getattr(fetched_root, LATEST_VERSION_CONTENT_PREFETCH_ATTR)
-        assert [v.content for v in latest] == ["newest-version-content"]
-
-
-class TestHasPrefetchedEffectiveContent:
-    """
-    DocumentSerializer.to_representation() only calls get_effective_content()
-    when has_prefetched_effective_content() says it's cheap -- otherwise a
-    caller that never set up an annotation or prefetch (TrashView,
-    GlobalSearchView, which build their own querysets and don't display
-    content at all) would pay for a per-instance query nobody asked for.
-    """
-
-    def test_false_with_no_annotation_or_prefetch(self) -> None:
-        document = Document()
-        assert has_prefetched_effective_content(document) is False
-
-    def test_true_with_effective_content_annotation(self) -> None:
-        document = Document()
-        document.effective_content = "resolved"
-        assert has_prefetched_effective_content(document) is True
-
-    def test_true_with_lean_prefetch_attr_even_when_empty(self) -> None:
-        document = Document()
-        setattr(document, LATEST_VERSION_CONTENT_PREFETCH_ATTR, [])
-        assert has_prefetched_effective_content(document) is True
-
-    def test_true_with_metadata_versions_prefetch_cache(self) -> None:
-        document = Document()
-        document._prefetched_objects_cache = {"versions": []}
-        assert has_prefetched_effective_content(document) is True
-
-
-def _get_effective_content_fallback_queries(
-    ctx: CaptureQueriesContext,
-) -> list[dict[str, str]]:
-    """
-    Document.get_effective_content()'s per-instance fallback (no annotation,
-    no prefetch) is a `.values_list("content", flat=True).first()` query --
-    a SELECT of just the content column. Distinct from get_versions()'s own,
-    unrelated per-instance metadata query (id/checksum/added/etc, no
-    content) run to build the "versions" response field, which isn't part
-    of what this test file covers.
-    """
-    return [
-        q
-        for q in ctx.captured_queries
-        if q["sql"].startswith('SELECT "documents_document"."content" FROM')
-    ]
-
-
-@pytest.mark.django_db
-class TestTrashAndGlobalSearchEffectiveContentIsNeverPerInstance:
-    """
-    TrashView and GlobalSearchView serialize Document instances with
-    DocumentSerializer too, but build their querysets independently of
-    DocumentViewSet.get_queryset(). TrashView doesn't display content at all,
-    so it keeps the document's own unresolved content; GlobalSearchView
-    annotates effective_content itself, so it shows the latest version's.
-    Neither should ever fall back to a per-instance query.
-    """
-
-    def test_trash_list_shows_unresolved_content_with_no_extra_query(
-        self,
-        admin_client: APIClient,
-    ) -> None:
-        # GIVEN a trashed root document whose own content differs from what
-        # a (also trashed, since deletion cascades) version would have had
-        root = DocumentFactory(content="own-content")
-        DocumentFactory(
-            root_document=root,
-            version_index=1,
-            content="version-content",
-        )
-        root.delete()
-
-        # WHEN listing trash
-        with CaptureQueriesContext(connection) as ctx:
-            response = admin_client.get("/api/trash/")
-
-        # THEN the response shows the document's own content...
-        assert response.status_code == status.HTTP_200_OK
-        [result] = [r for r in response.data["results"] if r["id"] == root.id]
-        assert result["content"] == "own-content"
-        # ...without ever querying for versions to resolve it
-        assert _get_effective_content_fallback_queries(ctx) == []
-
-    def test_global_search_db_only_shows_latest_version_content_with_no_extra_query(
-        self,
-        admin_client: APIClient,
-    ) -> None:
-        # GIVEN a root document, findable by title, whose own content
-        # differs from its latest version's
-        root = DocumentFactory(title="findme", content="own-content")
-        DocumentFactory(
-            root_document=root,
-            version_index=1,
-            content="version-content",
-        )
-
-        # WHEN using the global search endpoint's db_only mode
-        with CaptureQueriesContext(connection) as ctx:
-            response = admin_client.get(
-                "/api/search/?query=findme&db_only=true",
-            )
-
-        # THEN the response shows the latest version's content, resolved by
-        # GlobalSearchView's own effective_content annotation...
-        assert response.status_code == status.HTTP_200_OK
-        [result] = [d for d in response.data["documents"] if d["id"] == root.id]
-        assert result["content"] == "version-content"
-        # ...with no per-instance fallback query
-        assert _get_effective_content_fallback_queries(ctx) == []

src/documents/versioning.py

@@ -7,12 +7,9 @@ from typing import Any
 
 from django.db.models import F
 from django.db.models import OuterRef
-from django.db.models import Prefetch
 from django.db.models import QuerySet
 from django.db.models import Subquery
-from django.db.models import Window
 from django.db.models.functions import Coalesce
-from django.db.models.functions import RowNumber
 
 from documents.models import Document
 
@@ -49,68 +46,6 @@ def annotate_effective_content(documents: QuerySet[Document]) -> QuerySet[Docume
     )
 
 
-LATEST_VERSION_CONTENT_PREFETCH_ATTR = "_latest_version_content_prefetch"
-
-
-def latest_version_content_prefetch() -> Prefetch:
-    """
-    A Prefetch for Document.versions scoped to just the newest version's
-    content, for get_effective_content()'s fallback when no SQL annotation
-    is present.
-
-    Deliberately not merged into a metadata-only "versions" prefetch (the one
-    used for the serialized versions list): that one fetches every historical
-    version of every document, and pulling full OCR content for versions
-    nobody will read wastes DB transfer/memory at scale. This one is windowed
-    down to a single row per root, then bounded by Prefetch's own IN-list to
-    whatever page/result set it's attached to -- one cheap bulk query total,
-    not one per document and not one per version.
-    """
-    return Prefetch(
-        "versions",
-        queryset=(
-            Document.objects.filter(
-                root_document_id__isnull=False,
-                deleted_at__isnull=True,
-            )
-            .annotate(
-                rn=Window(
-                    RowNumber(),
-                    partition_by=F("root_document_id"),
-                    order_by=[
-                        F("version_index").desc(nulls_last=True),
-                        F("id").desc(),
-                    ],
-                ),
-            )
-            .filter(rn=1)
-            .only("id", "root_document_id", "content")
-        ),
-        to_attr=LATEST_VERSION_CONTENT_PREFETCH_ATTR,
-    )
-
-
-def has_prefetched_effective_content(document: Document) -> bool:
-    """
-    True if document.get_effective_content() can answer without an extra
-    per-instance query -- an SQL ``effective_content`` annotation, the lean
-    latest_version_content_prefetch(), or the metadata-only "versions"
-    prefetch is already present on the instance.
-
-    Callers that haven't set any of those up (e.g. views that build their
-    own querysets independently of DocumentViewSet.get_queryset(), like
-    TrashView or GlobalSearchView) intentionally don't pay for version-aware
-    content resolution -- see DocumentSerializer.to_representation(), which
-    uses this to decide whether to call get_effective_content() at all.
-    """
-    if hasattr(document, "effective_content"):
-        return True
-    if getattr(document, LATEST_VERSION_CONTENT_PREFETCH_ATTR, None) is not None:
-        return True
-    prefetched_cache = getattr(document, "_prefetched_objects_cache", None)
-    return isinstance(prefetched_cache, dict) and "versions" in prefetched_cache
-
-
 def sort_versions_newest_first(documents: list[Document]) -> list[Document]:
     """
     Same sorting as versions_newest_first()

src/documents/views.py

@@ -36,6 +36,7 @@ from django.db.migrations.recorder import MigrationRecorder
 from django.db.models import Avg
 from django.db.models import Case
 from django.db.models import Count
+from django.db.models import F
 from django.db.models import IntegerField
 from django.db.models import Max
 from django.db.models import Model
@@ -136,14 +137,12 @@ from documents.filters import CustomFieldFilterSet
 from documents.filters import DocumentFilterSet
 from documents.filters import DocumentsOrderingFilter
 from documents.filters import DocumentTypeFilterSet
-from documents.filters import EffectiveContentFilter
 from documents.filters import PaperlessTaskFilterSet
 from documents.filters import PermittedObjectsFilter
 from documents.filters import ShareLinkBundleFilterSet
 from documents.filters import ShareLinkFilterSet
 from documents.filters import StoragePathFilterSet
 from documents.filters import TagFilterSet
-from documents.filters import TitleContentFilter
 from documents.mail import EmailAttachment
 from documents.mail import send_email
 from documents.matching import match_correspondents
@@ -237,7 +236,6 @@ from documents.versioning import annotate_effective_content
 from documents.versioning import get_latest_version_for_root
 from documents.versioning import get_request_version_param
 from documents.versioning import get_root_document
-from documents.versioning import latest_version_content_prefetch
 from documents.versioning import resolve_requested_version_for_root
 from documents.versioning import versions_newest_first
 from paperless import version
@@ -1085,49 +1083,12 @@ class DocumentViewSet(
             ],
         }
 
-    @classmethod
-    def _content_filter_params(cls) -> tuple[str, ...]:
-        """
-        Query params whose filtering needs effective_content evaluated in SQL
-        against every candidate row -- see
-        _needs_effective_content_annotation(). Derived rather than
-        hand-maintained so a new content-filtering param counts automatically.
-        """
-        params = [
-            name
-            for name, f in DocumentFilterSet.declared_filters.items()
-            if isinstance(f, (TitleContentFilter, EffectiveContentFilter))
-        ]
-        if "effective_content" in cls.search_fields:
-            params.append(SearchFilter().search_param)
-        return tuple(params)
-
-    def _needs_effective_content_annotation(self) -> bool:
-        # effective_content is a per-row correlated subquery resolving each
-        # document's latest version. Filtering *on* it forces the database to
-        # evaluate it for every candidate row before reaching the LIMIT, which
-        # the root_document_id self-join makes pathological on MariaDB
-        # specifically once real candidate counts get large; otherwise the
-        # "versions" prefetch + Document.get_effective_content() resolves only
-        # the page that survives pagination. Every param here is deprecated in
-        # favor of the Tantivy-backed search endpoint (see filters.py's
-        # TitleContentFilter/EffectiveContentFilter docs), so pay that cost
-        # only when one is actually used. Blank values don't count, matching
-        # how those filters themselves no-op on them -- an empty `?search=`
-        # applies no predicate.
-        params = self.request.query_params
-        return any(
-            params.get(param, "").strip() for param in self._content_filter_params()
-        )
-
-    def _needs_effective_content_prefetch(self) -> bool:
-        # The prefetch spares get_effective_content() a per-instance fallback
-        # query, but only earns itself when content can reach the response.
-        # Mirror get_serializer() below: no `fields` param keeps every field.
-        fields_param = self.request.query_params.get("fields", None)
-        return fields_param is None or "content" in fields_param.split(",")
-
     def get_queryset(self):
+        latest_version_content = Subquery(
+            versions_newest_first(
+                Document.objects.filter(root_document=OuterRef("pk")),
+            ).values("content")[:1],
+        )
         # A correlated subquery avoids the LEFT JOIN + Count() this used to
         # be, which forced a GROUP BY aggregate over every matching document
         # before the query could even be sorted or limited.
@@ -1147,38 +1108,33 @@ class DocumentViewSet(
         # ObjectFilter.filter(). A blanket .distinct() here forces the
         # database to fully sort and dedupe every visible document before
         # it can apply LIMIT, which is disastrous at scale.
-        prefetches = [
-            Prefetch(
-                "versions",
-                queryset=Document.objects.only(
-                    "id",
-                    "added",
-                    "checksum",
-                    "version_label",
-                    "root_document_id",
-                    "version_index",
-                ),
-            ),
-            "tags",
-            Prefetch(
-                "custom_fields",
-                queryset=CustomFieldInstance.objects.select_related("field"),
-            ),
-            # NotesSerializer nests the author, this avoids query per note
-            Prefetch("notes", queryset=Note.objects.select_related("user")),
-        ]
-        if self._needs_effective_content_prefetch():
-            prefetches.append(latest_version_content_prefetch())
-        queryset = (
+        return (
             Document.objects.filter(root_document__isnull=True)
             .order_by("-created", "-id")
+            .annotate(effective_content=Coalesce(latest_version_content, F("content")))
             .annotate(num_notes=Coalesce(note_count, 0))
             .select_related("correspondent", "storage_path", "document_type", "owner")
-            .prefetch_related(*prefetches)
+            .prefetch_related(
+                Prefetch(
+                    "versions",
+                    queryset=Document.objects.only(
+                        "id",
+                        "added",
+                        "checksum",
+                        "version_label",
+                        "root_document_id",
+                        "version_index",
+                    ),
+                ),
+                "tags",
+                Prefetch(
+                    "custom_fields",
+                    queryset=CustomFieldInstance.objects.select_related("field"),
+                ),
+                # NotesSerializer nests the author, this avoids query per note
+                Prefetch("notes", queryset=Note.objects.select_related("user")),
+            )
         )
-        if self._needs_effective_content_annotation():
-            queryset = annotate_effective_content(queryset)
-        return queryset
 
     def get_serializer(self, *args, **kwargs):
         fields_param = self.request.query_params.get("fields", None)

src/paperless_mail/tasks.py

@@ -1,7 +1,9 @@
 import logging
 
+from celery import Task
 from celery import shared_task
 
+from documents.models import PaperlessTask
 from paperless_mail.mail import MailAccountHandler
 from paperless_mail.mail import MailError
 from paperless_mail.models import MailAccount
@@ -10,8 +12,27 @@ from paperless_mail.models import MailRule
 logger = logging.getLogger("paperless.mail.tasks")
 
 
-@shared_task
-def process_mail_accounts(account_ids: list[int] | None = None) -> str:
+@shared_task(bind=True)
+def process_mail_accounts(self: Task, account_ids: list[int] | None = None) -> str:
+    # A scheduled check can still be running (or queued) when the next one
+    # fires, e.g. a large attachment batch that takes longer to process than
+    # the check interval. ProcessedMail dedup only records a message once its
+    # handling has finished, so an overlapping run can still pick up the same
+    # not-yet-recorded message. Skip outright rather than race it.
+    other_mail_fetch_running = (
+        PaperlessTask.objects.filter(
+            task_type=PaperlessTask.TaskType.MAIL_FETCH,
+            status__in=[PaperlessTask.Status.PENDING, PaperlessTask.Status.STARTED],
+        )
+        .exclude(task_id=self.request.id)
+        .exists()
+    )
+    if other_mail_fetch_running:
+        logger.info(
+            "Mail account processing is already running; skipping this run.",
+        )
+        return "Skipped: mail account processing already in progress."
+
     total_new_documents = 0
     accounts = (
         MailAccount.objects.filter(pk__in=account_ids)

src/paperless_mail/tests/test_process_mail_accounts_overlap.py

@@ -0,0 +1,89 @@
+from unittest import mock
+
+import pytest
+
+from documents.models import PaperlessTask
+from paperless_mail import tasks
+from paperless_mail.tests.factories import MailAccountFactory
+from paperless_mail.tests.factories import MailRuleFactory
+
+
+@pytest.mark.django_db
+class TestProcessMailAccountsOverlap:
+    def test_skips_when_another_mail_fetch_task_is_running(self) -> None:
+        account = MailAccountFactory.create()
+        MailRuleFactory.create(account=account, enabled=True)
+
+        PaperlessTask.objects.create(
+            task_id="other-running-task",
+            task_type=PaperlessTask.TaskType.MAIL_FETCH,
+            trigger_source=PaperlessTask.TriggerSource.SCHEDULED,
+            status=PaperlessTask.Status.STARTED,
+        )
+
+        with mock.patch.object(
+            tasks.MailAccountHandler,
+            "handle_mail_account",
+        ) as mocked_handle:
+            result = tasks.process_mail_accounts()
+
+        mocked_handle.assert_not_called()
+        assert result == "Skipped: mail account processing already in progress."
+
+    def test_runs_when_no_other_mail_fetch_task_is_running(self) -> None:
+        account = MailAccountFactory.create()
+        MailRuleFactory.create(account=account, enabled=True)
+
+        with mock.patch.object(
+            tasks.MailAccountHandler,
+            "handle_mail_account",
+            return_value=0,
+        ) as mocked_handle:
+            result = tasks.process_mail_accounts()
+
+        mocked_handle.assert_called_once()
+        assert result == "No new documents were added."
+
+    def test_ignores_completed_mail_fetch_tasks(self) -> None:
+        account = MailAccountFactory.create()
+        MailRuleFactory.create(account=account, enabled=True)
+
+        PaperlessTask.objects.create(
+            task_id="finished-task",
+            task_type=PaperlessTask.TaskType.MAIL_FETCH,
+            trigger_source=PaperlessTask.TriggerSource.SCHEDULED,
+            status=PaperlessTask.Status.SUCCESS,
+        )
+
+        with mock.patch.object(
+            tasks.MailAccountHandler,
+            "handle_mail_account",
+            return_value=0,
+        ) as mocked_handle:
+            result = tasks.process_mail_accounts()
+
+        mocked_handle.assert_called_once()
+        assert result == "No new documents were added."
+
+    def test_does_not_skip_due_to_its_own_task_row(self) -> None:
+        account = MailAccountFactory.create()
+        MailRuleFactory.create(account=account, enabled=True)
+
+        PaperlessTask.objects.create(
+            task_id="self-task-id",
+            task_type=PaperlessTask.TaskType.MAIL_FETCH,
+            trigger_source=PaperlessTask.TriggerSource.SCHEDULED,
+            status=PaperlessTask.Status.STARTED,
+        )
+
+        with mock.patch.object(
+            tasks.MailAccountHandler,
+            "handle_mail_account",
+            return_value=0,
+        ) as mocked_handle:
+            result = tasks.process_mail_accounts.apply(
+                task_id="self-task-id",
+            ).result
+
+        mocked_handle.assert_called_once()
+        assert result == "No new documents were added."