day1 homework solution

GetSumByPageSize.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace GetSumGroupByPageSize
{
	[TestClass]
	public class UnitTest1
	{
		[TestMethod]
		public void Test_Pagesize_is_3_Sum_by_Cost_Should_Be_6_15_24_21()
		{
			var target = new SUT();
			var actual = target.GetSum(3, x => x.Cost).ToList();

			var expected = new List<int> { 6, 15, 24, 21 };

			CollectionAssert.AreEqual(expected, actual);
		}

		[TestMethod]
		public void Test_Pagesize_is_4_Sum_by_Revenue_Should_Be_50_66_60()
		{
			var target = new SUT();
			var actual = target.GetSum(4, x => x.Revenue).ToList();

			var expected = new List<int> { 50, 66, 60 };

			CollectionAssert.AreEqual(expected, actual);
		}
	}

	public class SUT
	{
		public IEnumerable<int> GetSum(int pageSize, Func<Product, int> selector)
		{
			var products = GetProducts().ToList();

			var index = 0;
			while (index <= products.Count)
			{
				yield return products.Skip(index).Take(pageSize).Sum(selector);
				index += pageSize;
			}
		}

		public IEnumerable<Product> GetProducts()
		{
			var products = new List<Product>()
			{
				new Product() { Id=1 ,Cost=1 ,Revenue=11,SellPrice=21 },
				new Product() { Id=2 ,Cost=2 ,Revenue=12,SellPrice=22 },
				new Product() { Id=3 ,Cost=3 ,Revenue=13,SellPrice=23 },
				new Product() { Id=4 ,Cost=4 ,Revenue=14,SellPrice=24 },
				new Product() { Id=5 ,Cost=5 ,Revenue=15,SellPrice=25 },
				new Product() { Id=6 ,Cost=6 ,Revenue=16,SellPrice=26 },
				new Product() { Id=7 ,Cost=7 ,Revenue=17,SellPrice=27 },
				new Product() { Id=8 ,Cost=8 ,Revenue=18,SellPrice=28 },
				new Product() { Id=9 ,Cost=9 ,Revenue=19,SellPrice=29 },
				new Product() { Id=10,Cost=10,Revenue=20,SellPrice=30 },
				new Product() { Id=11,Cost=11,Revenue=21,SellPrice=31 }
			};

			return products;
		}
	}

	public class Product
	{
		public int Id { get; set; }

		public int Cost { get; set; }

		public int Revenue { get; set; }

		public int SellPrice { get; set; }
	}
}

GetSumByPageSize_v2.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace GetSumGroupByPageSize
{
	[TestClass]
	public class UnitTest1
	{
		[TestMethod]
		public void Test_Pagesize_is_3_Sum_by_Cost_Should_Be_6_15_24_21()
		{
			var products = this.GetProducts();

			var actual = products.GetSum(3, x => x.Cost).ToList();

			var expected = new List<int> { 6, 15, 24, 21 };

			CollectionAssert.AreEqual(expected, actual);
		}

		[TestMethod]
		public void Test_Pagesize_is_4_Sum_by_Revenue_Should_Be_50_66_60()
		{
			var products = this.GetProducts();
			var actual = products.GetSum(4, x => x.Revenue).ToList();

			var expected = new List<int> { 50, 66, 60 };

			CollectionAssert.AreEqual(expected, actual);
		}

		private IEnumerable<Product> GetProducts()
		{
			var products = new List<Product>()
			{
				new Product() { Id=1 ,Cost=1 ,Revenue=11,SellPrice=21 },
				new Product() { Id=2 ,Cost=2 ,Revenue=12,SellPrice=22 },
				new Product() { Id=3 ,Cost=3 ,Revenue=13,SellPrice=23 },
				new Product() { Id=4 ,Cost=4 ,Revenue=14,SellPrice=24 },
				new Product() { Id=5 ,Cost=5 ,Revenue=15,SellPrice=25 },
				new Product() { Id=6 ,Cost=6 ,Revenue=16,SellPrice=26 },
				new Product() { Id=7 ,Cost=7 ,Revenue=17,SellPrice=27 },
				new Product() { Id=8 ,Cost=8 ,Revenue=18,SellPrice=28 },
				new Product() { Id=9 ,Cost=9 ,Revenue=19,SellPrice=29 },
				new Product() { Id=10,Cost=10,Revenue=20,SellPrice=30 },
				new Product() { Id=11,Cost=11,Revenue=21,SellPrice=31 }
			};

			return products;
		}
	}

	public static class EnumerableExtension
	{
		public static IEnumerable<int> GetSum<TSource>(this IEnumerable<TSource> source, int pageSize, Func<TSource, int> selector)
		{
			var index = 0;
			while (index <= source.Count())
			{
				yield return source.Skip(index).Take(pageSize).Sum(selector);
				index += pageSize;
			}
		}
	}

	public class Product
	{
		public int Id { get; set; }

		public int Cost { get; set; }

		public int Revenue { get; set; }

		public int SellPrice { get; set; }
	}
}

補充PageSize=1的測試案例如下:

        [TestMethod]
        public void Test_Pagesize_is_1_Sum_by_Cost_Should_Be_Same()
        {
		var products = this.GetProducts();

		var actual = products.GetSum(1, x => x.Cost).ToList();

		var expected = products.Select(x => x.Cost);

		CollectionAssert.AreEqual(expected, actual);
        }