public void GetConstraint()
        {
            TableDefinition table = new TableDefinition("Foo");
            IConstraintDefinition constraint = new DefaultConstraintDefinition("DF_Bar");

            table.AddConstraint(constraint);

            Assert.AreSame(constraint, table.GetConstraint("df_bar"));
            Assert.AreSame(constraint, table.GetConstraint("Df_BaR"));
            Assert.IsNull(table.GetConstraint("XX_Bar"));
        }