From 38660a612cd924199df83b93807604cadf6d5125 Mon Sep 17 00:00:00 2001
From: Sage Abdullah <me@laymonage.com>
Date: Thu, 8 May 2025 09:10:00 +0200
Subject: [PATCH] Refs #36143 -- Tested bulk_batch_size limit for bulk_update
 and bulk_create.

---
 tests/bulk_create/tests.py        |  8 ++++++++
 tests/queries/test_bulk_update.py | 11 +++++++++++
 2 files changed, 19 insertions(+)

diff --git a/tests/bulk_create/tests.py b/tests/bulk_create/tests.py
index e1b7e42d14..d590a292de 100644
--- a/tests/bulk_create/tests.py
+++ b/tests/bulk_create/tests.py
@@ -293,6 +293,14 @@ class BulkCreateTests(TestCase):
         with self.assertNumQueries(ceil(len(objs) / max_batch_size)):
             Country.objects.bulk_create(objs, batch_size=max_batch_size + 1)
 
+    @skipUnlessDBFeature("has_bulk_insert")
+    def test_max_batch_size(self):
+        objs = [Country(name=f"Country {i}") for i in range(1000)]
+        fields = ["name", "iso_two_letter", "description"]
+        max_batch_size = connection.ops.bulk_batch_size(fields, objs)
+        with self.assertNumQueries(ceil(len(objs) / max_batch_size)):
+            Country.objects.bulk_create(objs)
+
     @skipUnlessDBFeature("has_bulk_insert")
     def test_bulk_insert_expressions(self):
         Restaurant.objects.bulk_create(
diff --git a/tests/queries/test_bulk_update.py b/tests/queries/test_bulk_update.py
index 9fa9c3b9b8..765fa934ca 100644
--- a/tests/queries/test_bulk_update.py
+++ b/tests/queries/test_bulk_update.py
@@ -1,6 +1,8 @@
 import datetime
+from math import ceil
 
 from django.core.exceptions import FieldDoesNotExist
+from django.db import connection
 from django.db.models import F
 from django.db.models.functions import Lower
 from django.db.utils import IntegrityError
@@ -69,6 +71,15 @@ class BulkUpdateNoteTests(TestCase):
         with self.assertNumQueries(len(self.notes)):
             Note.objects.bulk_update(self.notes, fields=["note"], batch_size=1)
 
+    def test_max_batch_size(self):
+        max_batch_size = connection.ops.bulk_batch_size(
+            # PK is used twice, see comment in bulk_update().
+            [Note._meta.pk, Note._meta.pk, Note._meta.get_field("note")],
+            self.notes,
+        )
+        with self.assertNumQueries(ceil(len(self.notes) / max_batch_size)):
+            Note.objects.bulk_update(self.notes, fields=["note"])
+
     def test_unsaved_models(self):
         objs = self.notes + [Note(note="test", misc="test")]
         msg = "All bulk_update() objects must have a primary key set."