PYTHON-4915 - Add guidance on adding _id fields to documents to CRUD spec

Author: NoahStapp

test/mockupdb/test_id_ordering.py

@@ -0,0 +1,40 @@
+from __future__ import annotations
+
+from test import PyMongoTestCase
+
+import pytest
+
+try:
+    from mockupdb import MockupDB, OpMsg, going
+
+    _HAVE_MOCKUPDB = True
+except ImportError:
+    _HAVE_MOCKUPDB = False
+
+
+from bson.objectid import ObjectId
+
+pytestmark = pytest.mark.mockupdb
+
+
+class TestIdOrdering(PyMongoTestCase):
+    def test_id_ordering(self):
+        server = MockupDB()
+        server.autoresponds(
+            "hello",
+            isWritablePrimary=True,
+            msg="isdbgrid",
+            minWireVersion=0,
+            maxWireVersion=20,
+            helloOk=True,
+            serviceId=ObjectId(),
+        )
+        server.run()
+        self.addCleanup(server.stop)
+
+        client = self.simple_client(server.uri, loadBalanced=True)
+        collection = client.db.coll
+        with going(collection.insert_one, {"x": 1}):
+            request = server.receives(OpMsg({"insert": "coll"}))
+            self.assertEqual("_id", next(iter(request["documents"][0])))
+            request.reply({"ok": 1})