public bool isAvailableTest([PexAssumeUnderTest] ProductStock target, int id)
        {
            bool result = target.isAvailable(id);

            return(result);
            // TODO: add assertions to method ProductStockTest.isAvailableTest(ProductStock, Int32)
        }
        public void isAvailable_Test(int id, bool expected)
        {
            var result = itemsInStock.isAvailable(id);

            Assert.AreEqual(result, expected);
        }