From b67602c74b13cda35c089731bd16572d0d57e50c Mon Sep 17 00:00:00 2001
From: Salvo Polizzi <plzslv03a25c351k@studium.unict.it>
Date: Wed, 30 Oct 2024 09:09:28 +0100
Subject: [PATCH] Implemented reduce for optimizemigration.

---
 django/db/migrations/operations/models.py |  5 +++++
 docs/releases/5.2.txt                     |  2 +-
 tests/migrations/test_optimizer.py        | 27 +++++++++++++++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/django/db/migrations/operations/models.py b/django/db/migrations/operations/models.py
index 1b7db95b5c..ba1478bca0 100644
--- a/django/db/migrations/operations/models.py
+++ b/django/db/migrations/operations/models.py
@@ -1313,3 +1313,8 @@ class AlterConstraint(IndexOperation):
     @property
     def migration_name_fragment(self):
         return f"alter_{self.model_name_lower}_{self.constraint.name.lower()}"
+
+    def reduce(self, operation, app_label):
+        if isinstance(operation, AlterConstraint):
+            return [operation]
+        return super().reduce(operation, app_label)
diff --git a/docs/releases/5.2.txt b/docs/releases/5.2.txt
index bd8b1c6f8e..010569b346 100644
--- a/docs/releases/5.2.txt
+++ b/docs/releases/5.2.txt
@@ -253,7 +253,7 @@ Management Commands
 Migrations
 ~~~~~~~~~~
 
-* The new operation `AlterConstraint` is a noop operation that alters 
+* The new operation ``AlterConstraint`` is a no-op operation that alters 
   constraints without dropping and recreating indexes in the database.
 
 Models
diff --git a/tests/migrations/test_optimizer.py b/tests/migrations/test_optimizer.py
index 0a40b50edc..524dd0be63 100644
--- a/tests/migrations/test_optimizer.py
+++ b/tests/migrations/test_optimizer.py
@@ -1232,6 +1232,33 @@ class OptimizerTests(OptimizerTestBase):
             ],
         )
 
+    def test_alter_constraint(self):
+        gt_constraint = models.CheckConstraint(
+            condition=models.Q(pink__gt=2), name="constraint_pony_pink_gt_2"
+        )
+        gt_constraint_violation_msg = models.CheckConstraint(
+            condition=models.Q(pink__gt=2),
+            name="constraint_pony_pink_gt_2",
+            violation_error_message="error",
+        )
+        self.assertOptimizesTo(
+            [
+                migrations.AlterConstraint("Pony", gt_constraint.name, gt_constraint),
+                migrations.AlterConstraint(
+                    "Pony",
+                    gt_constraint_violation_msg.name,
+                    gt_constraint_violation_msg,
+                ),
+            ],
+            [
+                migrations.AlterConstraint(
+                    "Pony",
+                    gt_constraint_violation_msg.name,
+                    gt_constraint_violation_msg,
+                )
+            ],
+        )
+
     def test_create_model_add_index(self):
         self.assertOptimizesTo(
             [