Refs #11964 -- Made constraint support check respect required_db_features.

This will notably silence the warnings issued when running the test
suite on MySQL.

tests/constraints/models.py

@@ -2,12 +2,13 @@ from django.db import models
 
 
 class Product(models.Model):
-    name = models.CharField(max_length=255)
-    color = models.CharField(max_length=32, null=True)
     price = models.IntegerField(null=True)
     discounted_price = models.IntegerField(null=True)
 
     class Meta:
+        required_db_features = {
+            'supports_table_check_constraints',
+        }
         constraints = [
             models.CheckConstraint(
                 check=models.Q(price__gt=models.F('discounted_price')),
@@ -17,6 +18,15 @@ class Product(models.Model):
                 check=models.Q(price__gt=0),
                 name='%(app_label)s_%(class)s_price_gt_0',
             ),
+        ]
+
+
+class UniqueConstraintProduct(models.Model):
+    name = models.CharField(max_length=255)
+    color = models.CharField(max_length=32, null=True)
+
+    class Meta:
+        constraints = [
             models.UniqueConstraint(fields=['name', 'color'], name='name_color_uniq'),
             models.UniqueConstraint(
                 fields=['name'],
@@ -31,6 +41,9 @@ class AbstractModel(models.Model):
 
     class Meta:
         abstract = True
+        required_db_features = {
+            'supports_table_check_constraints',
+        }
         constraints = [
             models.CheckConstraint(
                 check=models.Q(age__gte=18),