fix: send sync-collection with Depth: 0

caldav/async_davclient.py

@@ -842,7 +842,7 @@ async def sync_collection(
         url: str | None = None,
         sync_token: str | None = None,
         props: list[str] | None = None,
-        depth: int = 1,
+        depth: int = 0,
         headers: Mapping[str, str] | None = None,
     ) -> DAVResponse:
         """
@@ -852,7 +852,7 @@ async def sync_collection(
             url: Target calendar URL (defaults to self.url).
             sync_token: Previous sync token (None for initial sync).
             props: Properties to include in response.
-            depth: Search depth.
+            depth: Depth header; RFC 6578 defines sync-collection for 0 only.
             headers: Additional headers.
 
         Returns:

caldav/collection.py

@@ -1796,23 +1796,26 @@ def _href_to_url(self, href: str) -> "URL | str":
         return url
 
     def _request_report_build_resultlist(
-        self, xml, comp_class=None, props=None, no_calendardata=False
+        self, xml, comp_class=None, props=None, no_calendardata=False, depth=1
     ) -> "tuple[Any, list[CalendarObjectResource]] | Coroutine[Any, Any, tuple[Any, list[CalendarObjectResource]]]":
         """
         Takes some input XML, does a report query on a calendar object
         and returns the resource objects found.
 
+        ``depth`` is 1 for calendar-query; sync-collection needs 0
+        (RFC 6578 section 3.2).
+
         For async clients, returns a coroutine that must be awaited.
         """
         props_ = [cdav.CalendarData()] if props is None else [cdav.CalendarData()] + props
         if self.is_async_client:
-            return self._async_request_report_build_resultlist(xml, comp_class, props_)
-        response = self._query(xml, 1, "report")
+            return self._async_request_report_build_resultlist(xml, comp_class, props_, depth)
+        response = self._query(xml, depth, "report")
         return self._post_request_report_build_resultlist(response, comp_class, props_)
 
-    async def _async_request_report_build_resultlist(self, xml, comp_class, props_):
+    async def _async_request_report_build_resultlist(self, xml, comp_class, props_, depth=1):
         """Async implementation of _request_report_build_resultlist."""
-        response = await self._query(xml, 1, "report")
+        response = await self._query(xml, depth, "report")
         return self._post_request_report_build_resultlist(response, comp_class, props_)
 
     def _populate_searcher(self, my_searcher, searchargs: dict, sort_reverse: bool) -> None:
@@ -2541,7 +2544,7 @@ def get_objects_by_sync_token(
                         sync_token=token, props=["getetag"]
                     )
                     (response, objects) = self._request_report_build_resultlist(
-                        root, props=[dav.GetEtag()], no_calendardata=True
+                        root, props=[dav.GetEtag()], no_calendardata=True, depth=0
                     )
                     (token, truncated, again) = self._absorb_sync_page(
                         response, objects, collected, token, deleted
@@ -2642,7 +2645,7 @@ async def _async_get_objects_by_sync_token(
                         sync_token=token, props=["getetag"]
                     )
                     (response, objects) = await self._request_report_build_resultlist(
-                        root, props=[dav.GetEtag()], no_calendardata=True
+                        root, props=[dav.GetEtag()], no_calendardata=True, depth=0
                     )
                     (token, truncated, again) = self._absorb_sync_page(
                         response, objects, collected, token, deleted

changes/+sync-collection-depth-0.fixed.md

@@ -0,0 +1 @@
+The sync-collection REPORT (`Calendar.get_objects_by_sync_token()`, `AsyncDAVClient.sync_collection()`) is now sent with `Depth: 0`, as [RFC 6578 section 3.2](https://datatracker.ietf.org/doc/html/rfc6578#section-3.2) requires, instead of `Depth: 1`; the `depth` parameter of `AsyncDAVClient.sync_collection()` now defaults to 0.  None of the servers in the test suite behaves differently, but a strict server may reject the old request with a 400.

tests/test_async_davclient.py

@@ -2301,6 +2301,8 @@ async def test_follows_the_token_until_complete(self) -> None:
 
         assert client.report.await_count == 2
         bodies = [to_normal_str(c.args[1]) for c in client.report.call_args_list]
+        ## RFC 6578 section 3.2: sync-collection is only defined for Depth: 0
+        assert [c.args[2] for c in client.report.call_args_list] == [0, 0]
         assert "tok-1" in bodies[0]
         assert "tok-2" in bodies[1]
         assert result.sync_token == "tok-3"
@@ -2434,3 +2436,4 @@ async def test_sync_collection_reports_truncation(self) -> None:
         assert response.sync_truncated is True
         assert response.sync_token == "tok-2"
         assert [r.href for r in response.results] == ["/dav/cal/a.ics"]
+        assert client.request.call_args.args[3]["Depth"] == "0"

tests/test_caldav_unit.py

@@ -4382,10 +4382,12 @@ class CapturingClient(MockedDAVClient):
             def __init__(self):
                 super().__init__("<multistatus xmlns='DAV:'/>")
                 self.report_bodies = []
+                self.report_depths = []
 
             def request(self, url=None, method="GET", body=None, headers=None, *args, **kwargs):
                 if method == "REPORT" and body:
                     self.report_bodies.append(body)
+                    self.report_depths.append((headers or {}).get("Depth"))
                 return super().request(url, method, body, headers, *args, **kwargs)
 
         client = CapturingClient()
@@ -4402,6 +4404,9 @@ def request(self, url=None, method="GET", body=None, headers=None, *args, **kwar
         # Must NOT contain bare date strings without time component
         assert "20260501Z" not in body
         assert "20260601Z" not in body
+        ## calendar-query is a Depth: 1 REPORT (RFC 4791 section 7.8),
+        ## unlike sync-collection, which shares the helper
+        assert client.report_depths[0] == "1"
 
     def test_searcher_coerces_date_to_datetime(self):
         """calendar.searcher(start=date(...)) must store datetime on the searcher,
@@ -7596,6 +7601,8 @@ def test_untruncated_reply_is_a_single_request(self):
         client, calendar = self._calendar(sync_page({"a.ics": '"a1"'}, "tok-2", truncated=False))
         result = calendar.get_objects_by_sync_token("tok-1")
         assert client.report.call_count == 1
+        ## RFC 6578 section 3.2: sync-collection is only defined for Depth: 0
+        assert client.report.call_args.args[2] == 0
         assert result.truncated is False
         assert result.sync_token == "tok-2"
         assert len(result) == 1