DB.Migrator().CreateConstraint(&User{}, name)
		}

		if err := DB.Migrator().DropConstraint(&User{}, name); err != nil {
			t.Fatalf("failed to drop constraint %v, got error %v", name, err)
		}

		if DB.Migrator().HasConstraint(&User{}, name) {
			t.Fatalf("constraint %v should been deleted", name)
		}

		if err := DB.Migrator().CreateConstraint(&User{}, name); err != nil {