Fixed #35038 -- Created AlterConstraint operation.

3 files changed, 214 insertions, 0 deletions

diff --git a/tests/migrations/test_autodetector.py b/tests/migrations/test_autodetector.py
index d93114564a..de62170eb3 100644
--- a/tests/migrations/test_autodetector.py
+++ b/tests/migrations/test_autodetector.py
@@ -2969,6 +2969,71 @@ class AutodetectorTests(BaseAutodetectorTests):
             ["CreateModel", "AddField", "AddIndex"],
         )
 
+    def test_alter_constraint(self):
+        book_constraint = models.CheckConstraint(
+            condition=models.Q(title__contains="title"),
+            name="title_contains_title",
+        )
+        book_altered_constraint = models.CheckConstraint(
+            condition=models.Q(title__contains="title"),
+            name="title_contains_title",
+            violation_error_code="error_code",
+        )
+        author_altered_constraint = models.CheckConstraint(
+            condition=models.Q(name__contains="Bob"),
+            name="name_contains_bob",
+            violation_error_message="Name doesn't contain Bob",
+        )
+
+        book_check_constraint = copy.deepcopy(self.book)
+        book_check_constraint_with_error_message = copy.deepcopy(self.book)
+        author_name_check_constraint_with_error_message = copy.deepcopy(
+            self.author_name_check_constraint
+        )
+
+        book_check_constraint.options = {"constraints": [book_constraint]}
+        book_check_constraint_with_error_message.options = {
+            "constraints": [book_altered_constraint]
+        }
+        author_name_check_constraint_with_error_message.options = {
+            "constraints": [author_altered_constraint]
+        }
+
+        changes = self.get_changes(
+            [self.author_name_check_constraint, book_check_constraint],
+            [
+                author_name_check_constraint_with_error_message,
+                book_check_constraint_with_error_message,
+            ],
+        )
+
+        self.assertNumberMigrations(changes, "testapp", 1)
+        self.assertOperationTypes(changes, "testapp", 0, ["AlterConstraint"])
+        self.assertOperationAttributes(
+            changes,
+            "testapp",
+            0,
+            0,
+            model_name="author",
+            name="name_contains_bob",
+            constraint=author_altered_constraint,
+        )
+
+        self.assertNumberMigrations(changes, "otherapp", 1)
+        self.assertOperationTypes(changes, "otherapp", 0, ["AlterConstraint"])
+        self.assertOperationAttributes(
+            changes,
+            "otherapp",
+            0,
+            0,
+            model_name="book",
+            name="title_contains_title",
+            constraint=book_altered_constraint,
+        )
+        self.assertMigrationDependencies(
+            changes, "otherapp", 0, [("testapp", "auto_1")]
+        )
+
     def test_remove_constraints(self):
         """Test change detection of removed constraints."""
         changes = self.get_changes(
diff --git a/tests/migrations/test_operations.py b/tests/migrations/test_operations.py
index 3ac813b899..da0ec93dcd 100644
--- a/tests/migrations/test_operations.py
+++ b/tests/migrations/test_operations.py
@@ -4366,6 +4366,81 @@ class OperationTests(OperationTestBase):
             {"model_name": "Pony", "name": "test_remove_constraint_pony_pink_gt_2"},
         )
 
+    def test_alter_constraint(self):
+        constraint = models.UniqueConstraint(
+            fields=["pink"], name="test_alter_constraint_pony_fields_uq"
+        )
+        project_state = self.set_up_test_model(
+            "test_alterconstraint", constraints=[constraint]
+        )
+
+        new_state = project_state.clone()
+        violation_error_message = "Pink isn't unique"
+        uq_constraint = models.UniqueConstraint(
+            fields=["pink"],
+            name="test_alter_constraint_pony_fields_uq",
+            violation_error_message=violation_error_message,
+        )
+        uq_operation = migrations.AlterConstraint(
+            "Pony", "test_alter_constraint_pony_fields_uq", uq_constraint
+        )
+        self.assertEqual(
+            uq_operation.describe(),
+            "Alter constraint test_alter_constraint_pony_fields_uq on Pony",
+        )
+        self.assertEqual(
+            uq_operation.formatted_description(),
+            "~ Alter constraint test_alter_constraint_pony_fields_uq on Pony",
+        )
+        self.assertEqual(
+            uq_operation.migration_name_fragment,
+            "alter_pony_test_alter_constraint_pony_fields_uq",
+        )
+
+        uq_operation.state_forwards("test_alterconstraint", new_state)
+        self.assertEqual(
+            project_state.models["test_alterconstraint", "pony"]
+            .options["constraints"][0]
+            .violation_error_message,
+            "Constraint “%(name)s” is violated.",
+        )
+        self.assertEqual(
+            new_state.models["test_alterconstraint", "pony"]
+            .options["constraints"][0]
+            .violation_error_message,
+            violation_error_message,
+        )
+
+        with connection.schema_editor() as editor, self.assertNumQueries(0):
+            uq_operation.database_forwards(
+                "test_alterconstraint", editor, project_state, new_state
+            )
+        self.assertConstraintExists(
+            "test_alterconstraint_pony",
+            "test_alter_constraint_pony_fields_uq",
+            value=False,
+        )
+        with connection.schema_editor() as editor, self.assertNumQueries(0):
+            uq_operation.database_backwards(
+                "test_alterconstraint", editor, project_state, new_state
+            )
+        self.assertConstraintExists(
+            "test_alterconstraint_pony",
+            "test_alter_constraint_pony_fields_uq",
+            value=False,
+        )
+        definition = uq_operation.deconstruct()
+        self.assertEqual(definition[0], "AlterConstraint")
+        self.assertEqual(definition[1], [])
+        self.assertEqual(
+            definition[2],
+            {
+                "model_name": "Pony",
+                "name": "test_alter_constraint_pony_fields_uq",
+                "constraint": uq_constraint,
+            },
+        )
+
     def test_add_partial_unique_constraint(self):
         project_state = self.set_up_test_model("test_addpartialuniqueconstraint")
         partial_unique_constraint = models.UniqueConstraint(
diff --git a/tests/migrations/test_optimizer.py b/tests/migrations/test_optimizer.py
index 0a40b50edc..a871e67a45 100644
--- a/tests/migrations/test_optimizer.py
+++ b/tests/migrations/test_optimizer.py
@@ -1232,6 +1232,80 @@ class OptimizerTests(OptimizerTestBase):
             ],
         )
 
+    def test_multiple_alter_constraints(self):
+        gt_constraint_violation_msg_added = models.CheckConstraint(
+            condition=models.Q(pink__gt=2),
+            name="pink_gt_2",
+            violation_error_message="ERROR",
+        )
+        gt_constraint_violation_msg_altered = models.CheckConstraint(
+            condition=models.Q(pink__gt=2),
+            name="pink_gt_2",
+            violation_error_message="error",
+        )
+        self.assertOptimizesTo(
+            [
+                migrations.AlterConstraint(
+                    "Pony", "pink_gt_2", gt_constraint_violation_msg_added
+                ),
+                migrations.AlterConstraint(
+                    "Pony", "pink_gt_2", gt_constraint_violation_msg_altered
+                ),
+            ],
+            [
+                migrations.AlterConstraint(
+                    "Pony", "pink_gt_2", gt_constraint_violation_msg_altered
+                )
+            ],
+        )
+        other_constraint_violation_msg = models.CheckConstraint(
+            condition=models.Q(weight__gt=3),
+            name="pink_gt_3",
+            violation_error_message="error",
+        )
+        self.assertDoesNotOptimize(
+            [
+                migrations.AlterConstraint(
+                    "Pony", "pink_gt_2", gt_constraint_violation_msg_added
+                ),
+                migrations.AlterConstraint(
+                    "Pony", "pink_gt_3", other_constraint_violation_msg
+                ),
+            ]
+        )
+
+    def test_alter_remove_constraint(self):
+        self.assertOptimizesTo(
+            [
+                migrations.AlterConstraint(
+                    "Pony",
+                    "pink_gt_2",
+                    models.CheckConstraint(
+                        condition=models.Q(pink__gt=2), name="pink_gt_2"
+                    ),
+                ),
+                migrations.RemoveConstraint("Pony", "pink_gt_2"),
+            ],
+            [migrations.RemoveConstraint("Pony", "pink_gt_2")],
+        )
+
+    def test_add_alter_constraint(self):
+        constraint = models.CheckConstraint(
+            condition=models.Q(pink__gt=2), name="pink_gt_2"
+        )
+        constraint_with_error = models.CheckConstraint(
+            condition=models.Q(pink__gt=2),
+            name="pink_gt_2",
+            violation_error_message="error",
+        )
+        self.assertOptimizesTo(
+            [
+                migrations.AddConstraint("Pony", constraint),
+                migrations.AlterConstraint("Pony", "pink_gt_2", constraint_with_error),
+            ],
+            [migrations.AddConstraint("Pony", constraint_with_error)],
+        )
+
     def test_create_model_add_index(self):
         self.assertOptimizesTo(
             [