Fixed #30581 -- Added support for Meta.constraints validation.

Thanks Simon Charette, Keryn Knight, and Mariusz Felisiak for reviews.

tests/validation/test_constraints.py

@@ -0,0 +1,95 @@
+from django.core.exceptions import ValidationError
+from django.test import TestCase, skipUnlessDBFeature
+
+from .models import (
+    ChildProduct,
+    ChildUniqueConstraintProduct,
+    Product,
+    UniqueConstraintConditionProduct,
+    UniqueConstraintProduct,
+)
+
+
+class PerformConstraintChecksTest(TestCase):
+    @skipUnlessDBFeature("supports_table_check_constraints")
+    def test_full_clean_with_check_constraints(self):
+        product = Product(price=10, discounted_price=15)
+        with self.assertRaises(ValidationError) as cm:
+            product.full_clean()
+        self.assertEqual(
+            cm.exception.message_dict,
+            {
+                "__all__": [
+                    "Constraint “price_gt_discounted_price_validation” is violated."
+                ]
+            },
+        )
+
+    @skipUnlessDBFeature("supports_table_check_constraints")
+    def test_full_clean_with_check_constraints_on_child_model(self):
+        product = ChildProduct(price=10, discounted_price=15)
+        with self.assertRaises(ValidationError) as cm:
+            product.full_clean()
+        self.assertEqual(
+            cm.exception.message_dict,
+            {
+                "__all__": [
+                    "Constraint “price_gt_discounted_price_validation” is violated."
+                ]
+            },
+        )
+
+    @skipUnlessDBFeature("supports_table_check_constraints")
+    def test_full_clean_with_check_constraints_disabled(self):
+        product = Product(price=10, discounted_price=15)
+        product.full_clean(validate_constraints=False)
+
+    def test_full_clean_with_unique_constraints(self):
+        UniqueConstraintProduct.objects.create(name="product", color="yellow", rank=1)
+        tests = [
+            UniqueConstraintProduct(name="product", color="yellow", rank=1),
+            # Child model.
+            ChildUniqueConstraintProduct(name="product", color="yellow", rank=1),
+        ]
+        for product in tests:
+            with self.subTest(model=product.__class__.__name__):
+                with self.assertRaises(ValidationError) as cm:
+                    product.full_clean()
+                self.assertEqual(
+                    cm.exception.message_dict,
+                    {
+                        "__all__": [
+                            "Unique constraint product with this Name and Color "
+                            "already exists."
+                        ],
+                        "rank": [
+                            "Unique constraint product with this Rank already exists."
+                        ],
+                    },
+                )
+
+    def test_full_clean_with_unique_constraints_disabled(self):
+        UniqueConstraintProduct.objects.create(name="product", color="yellow", rank=1)
+        product = UniqueConstraintProduct(name="product", color="yellow", rank=1)
+        product.full_clean(validate_constraints=False)
+
+    @skipUnlessDBFeature("supports_partial_indexes")
+    def test_full_clean_with_partial_unique_constraints(self):
+        UniqueConstraintConditionProduct.objects.create(name="product")
+        product = UniqueConstraintConditionProduct(name="product")
+        with self.assertRaises(ValidationError) as cm:
+            product.full_clean()
+        self.assertEqual(
+            cm.exception.message_dict,
+            {
+                "__all__": [
+                    "Constraint “name_without_color_uniq_validation” is violated."
+                ]
+            },
+        )
+
+    @skipUnlessDBFeature("supports_partial_indexes")
+    def test_full_clean_with_partial_unique_constraints_disabled(self):
+        UniqueConstraintConditionProduct.objects.create(name="product")
+        product = UniqueConstraintConditionProduct(name="product")
+        product.full_clean(validate_constraints=False)