test(indexer): isolate TestIndexLongDocument from a configured PAGEINDEX_API_KEY

These tests drive the LOCAL indexing path with a fake PDF. When a developer has
PAGEINDEX_API_KEY set, index_long_document takes the cloud branch and
_get_pdf_page_count tries to open the fake PDF and raises (FileDataError). Add a
class-scoped autouse fixture that unsets the key by default; the cloud-path tests
in the class re-enable it via monkeypatch.setenv.

Author: KylinMountain

tests/test_indexer.py

@@ -3,6 +3,7 @@
 
 from unittest.mock import MagicMock, patch
 
+import pytest
 
 from openkb.indexer import IndexResult, _normalize_page_content, index_long_document
 
@@ -37,6 +38,14 @@ def test_rejects_unusable_shapes(self):
 
 
 class TestIndexLongDocument:
+    @pytest.fixture(autouse=True)
+    def _local_path_by_default(self, monkeypatch):
+        # These tests exercise the LOCAL indexing path; unset PAGEINDEX_API_KEY
+        # so they are deterministic regardless of a developer's configured key
+        # (otherwise the cloud branch reads the page count from the fake PDF and
+        # raises). Cloud-path tests in this class re-enable it via setenv.
+        monkeypatch.delenv("PAGEINDEX_API_KEY", raising=False)
+
     def _make_fake_collection(self, doc_id: str, sample_tree: dict):
         """Build a mock Collection that returns the sample_tree fixture data."""
         col = MagicMock()