Object クラス拡張

gistfile1.cs

using System;

namespace MktSys.Lib.Extensions
{
    /// <summary>
    /// Object 拡張メソッド定義クラス
    /// </summary>
    public static class ObjectExtension
    {
        /// <summary>
        /// オブジェクトに Tap メソッドを追加する。<br />
        /// オブジェクト自身に指定の処理を行い、オブジェクト自身を返却する。
        /// </summary>
        /// <typeparam name="T">対象の型</typeparam>
        /// <param name="source">対象オブジェクト</param>
        /// <param name="action">処理</param>
        /// <returns>対象オブジェクト自身</returns>
        public static T Tap<T>(this T source, Action<T> action)
        {
            if (source == null || action == null) { return source; }

            action(source);
            return source;
        }
    }
}

// test
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.VisualStudio.TestTools.UnitTesting; // or NUnit.Framework
using MktSys.Lib.Extensions;

namespace MktSys.Lib.Extensions.Test
{
    [TestClass]
    public class ObjectExtensionTest
    {
        #region Object#Tap
        [TestMethod]
        public void TestTapReference()
        {
            var list = new List<int>() { 1, 2, 3, 4 };
            var newList = list.Tap(l => l.Add(5));
            Assert.ReferenceEquals(newList, list);
        }

        [TestMethod]
        public void TestTapAction()
        {
            var list = new List<int>() { 1, 2, 3, 4 };
            var expected = Enumerable.Range(1, 5);
            var newList = list.Tap(l => l.Add(5));
            Assert.AreEqual(5, list.Count);
            Assert.IsTrue(list.SequenceEqual(expected));
            Assert.AreEqual(5, newList.Count);
            Assert.IsTrue(newList.SequenceEqual(expected));
        }

        [TestMethod]
        public void TestTapWithNullSource()
        {
            var actionExecuted = false;
            Object obj = null;
            obj.Tap(_ => actionExecuted = true);
            Assert.IsFalse(actionExecuted);
        }

        [TestMethod]
        public void TestTapWithNullAction()
        {
            var actionExecuted = false;
            Object obj = new Object();
            obj.Tap(null);
            Assert.IsFalse(actionExecuted);
        }
        #endregion
    }
}