fix(api): return total count on related endpoint (#16397)

* fix(api): return total count on related endpoint

* update response code from 400 to 422

tests/integration_tests/base_api_tests.py

@@ -202,6 +202,40 @@ class ApiOwnersTestCaseMixin:
         for expected_user in expected_users:
             assert expected_user in response_users
 
+    def test_get_related_owners_paginated(self):
+        """
+        API: Test get related owners with pagination
+        """
+        self.login(username="admin")
+        page_size = 1
+        argument = {"page_size": page_size}
+        uri = f"api/v1/{self.resource_name}/related/owners?q={prison.dumps(argument)}"
+        rv = self.client.get(uri)
+        assert rv.status_code == 200
+        response = json.loads(rv.data.decode("utf-8"))
+        users = db.session.query(security_manager.user_model).all()
+
+        # the count should correspond with the total number of users
+        assert response["count"] == len(users)
+
+        # the length of the result should be at most equal to the page size
+        assert len(response["result"]) == min(page_size, len(users))
+
+        # make sure all received users are included in the full set of users
+        all_users = [str(user) for user in users]
+        for received_user in [result["text"] for result in response["result"]]:
+            assert received_user in all_users
+
+    def test_get_ids_related_owners_paginated(self):
+        """
+        API: Test get related owners with pagination returns 422
+        """
+        self.login(username="admin")
+        argument = {"page": 1, "page_size": 1, "include_ids": [2]}
+        uri = f"api/v1/{self.resource_name}/related/owners?q={prison.dumps(argument)}"
+        rv = self.client.get(uri)
+        assert rv.status_code == 422
+
     def test_get_filter_related_owners(self):
         """
         API: Test get filter related owners