test(integration): add tests for calendar delegation

Signed-off-by: Hamza <hamzamahjoubi221@gmail.com>

Author: hamza221

build/integration/dav_features/caldav-delegation.feature

@@ -0,0 +1,17 @@
+# SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+# SPDX-License-Identifier: AGPL-3.0-or-later
+Feature: calendar delegation
+  Calendar delegation grants another user/principal control of a calendar account,
+  including all calendars the delegator can access.
+
+  Scenario: admin grants user0 read access to her calendar account
+    Given user "admin" exists
+    And user "user0" exists
+    When "admin" updates property "{DAV:}group-member-set" to href "/remote.php/dav/principals/users/user0" of principal "users/admin/calendar-proxy-read" on the endpoint "/remote.php/dav/principals/"
+    Then The CalDAV response should be multi status
+
+  Scenario: admin grants write access to her calendar account
+    Given user "admin" exists
+    And user "user0" exists
+    When "admin" updates property "{DAV:}group-member-set" to href "/remote.php/dav/principals/users/user0" of principal "users/admin/calendar-proxy-write" on the endpoint "/remote.php/dav/principals/"
+    Then The CalDAV response should be multi status