Fixed #35103 -- Used provided error code and message when fields is set without a condition on UniqueConstraint.

tests/constraints/tests.py

@@ -953,6 +953,41 @@ class UniqueConstraintTests(TestCase):
                 ChildUniqueConstraintProduct(name=self.p1.name, color=self.p1.color),
             )
 
+    def test_validate_unique_custom_code_and_message(self):
+        product = UniqueConstraintProduct.objects.create(
+            name="test", color="red", age=42
+        )
+        code = "custom_code"
+        message = "Custom message"
+        multiple_fields_constraint = models.UniqueConstraint(
+            fields=["color", "age"],
+            name="color_age_uniq",
+            violation_error_code=code,
+            violation_error_message=message,
+        )
+        single_field_constraint = models.UniqueConstraint(
+            fields=["color"],
+            name="color_uniq",
+            violation_error_code=code,
+            violation_error_message=message,
+        )
+
+        with self.assertRaisesMessage(ValidationError, message) as cm:
+            multiple_fields_constraint.validate(
+                UniqueConstraintProduct,
+                UniqueConstraintProduct(
+                    name="new-test", color=product.color, age=product.age
+                ),
+            )
+        self.assertEqual(cm.exception.code, code)
+
+        with self.assertRaisesMessage(ValidationError, message) as cm:
+            single_field_constraint.validate(
+                UniqueConstraintProduct,
+                UniqueConstraintProduct(name="new-test", color=product.color),
+            )
+        self.assertEqual(cm.exception.code, code)
+
     @skipUnlessDBFeature("supports_table_check_constraints")
     def test_validate_fields_unattached(self):
         Product.objects.create(price=42)