Refs #34338 -- Fixed isolation of constraints tests.

Regression in 5b3d3e400a.

tests/constraints/models.py

@@ -34,7 +34,13 @@ class UniqueConstraintProduct(models.Model):
 
     class Meta:
         constraints = [
-            models.UniqueConstraint(fields=["name", "color"], name="name_color_uniq"),
+            models.UniqueConstraint(
+                fields=["name", "color"],
+                name="name_color_uniq",
+                # Custom message and error code are ignored.
+                violation_error_code="custom_code",
+                violation_error_message="Custom message",
+            )
         ]
 
 

tests/constraints/tests.py

@@ -744,9 +744,6 @@ class UniqueConstraintTests(TestCase):
 
     def test_validate(self):
         constraint = UniqueConstraintProduct._meta.constraints[0]
-        # Custom message and error code are ignored.
-        constraint.violation_error_message = "Custom message"
-        constraint.violation_error_code = "custom_code"
         msg = "Unique constraint product with this Name and Color already exists."
         non_unique_product = UniqueConstraintProduct(
             name=self.p1.name, color=self.p1.color
@@ -811,9 +808,13 @@ class UniqueConstraintTests(TestCase):
     @skipUnlessDBFeature("supports_partial_indexes")
     def test_validate_conditon_custom_error(self):
         p1 = UniqueConstraintConditionProduct.objects.create(name="p1")
-        constraint = UniqueConstraintConditionProduct._meta.constraints[0]
-        constraint.violation_error_message = "Custom message"
-        constraint.violation_error_code = "custom_code"
+        constraint = models.UniqueConstraint(
+            fields=["name"],
+            name="name_without_color_uniq",
+            condition=models.Q(color__isnull=True),
+            violation_error_code="custom_code",
+            violation_error_message="Custom message",
+        )
         msg = "Custom message"
         with self.assertRaisesMessage(ValidationError, msg) as cm:
             constraint.validate(