IList<T> Shuffle extension

src/Z.Collections/System.Collections.Generic.IList[T]/IList[T].Shuffle.cs

@@ -0,0 +1,32 @@
+// Description: C# Extension Methods Library to enhances the .NET Framework by adding hundreds of new methods. It drastically increases developers productivity and code readability. Support C# and VB.NET
+// Website & Documentation: https://github.com/zzzprojects/Z.ExtensionMethods
+// Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
+// License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
+// More projects: http://www.zzzprojects.com/
+// Copyright � ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+public static partial class Extensions
+{
+    private static readonly Random _random = new Random();
+
+    /// <summary>
+    /// An IList&lt;T&gt; extension method that shuffles items in a collection.
+    /// </summary>
+    /// <typeparam name="T">Generic type parameter.</typeparam>
+    /// <param name="this">The @this to act on.</param>
+    public static void Shuffle<T>(this IList<T> @this)
+    {
+        int length = @this.Count;
+        for (int i = 0; i < length; i++)
+        {
+            int randomIndex = i + _random.Next(length - i);
+            T item = @this.ElementAt(randomIndex);
+            @this[randomIndex] = @this[i];
+            @this[i] = item;
+        }
+    }
+}

src/Z.Collections/System.Collections.Generic.IList[T]/IList[T].Swap.cs

@@ -10,7 +10,7 @@
 public static partial class Extensions
 {
     /// <summary>
-    /// An ICollection&lt;T&gt; extension method that swaps item only when it exists in a collection.
+    /// An IList&lt;T&gt; extension method that swaps item only when it exists in a collection.
     /// </summary>
     /// <typeparam name="T">Generic type parameter.</typeparam>
     /// <param name="this">The @this to act on.</param>

src/Z.Collections/Z.Collections.csproj

@@ -63,6 +63,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="System.Collections.Generic.IList[T]\IList[T].Shuffle.cs" />
     <Compile Include="System.Collections.Generic.IList[T]\IList[T].Swap.cs" />
     <Compile Include="System.Collections.Generic.ICollection[T]\ICollection[T].AddIf.cs" />
     <Compile Include="System.Collections.Generic.ICollection[T]\ICollection[T].AddIfNotContains.cs" />

test/Z.Collections.Test/System.Collections.Generic.IList[T]/IList[T].Shuffle.cs

@@ -0,0 +1,44 @@
+// Description: C# Extension Methods Library to enhances the .NET Framework by adding hundreds of new methods. It drastically increases developers productivity and code readability. Support C# and VB.NET
+// Website & Documentation: https://github.com/zzzprojects/Z.ExtensionMethods
+// Forum: https://github.com/zzzprojects/Z.ExtensionMethods/issues
+// License: https://github.com/zzzprojects/Z.ExtensionMethods/blob/master/LICENSE
+// More projects: http://www.zzzprojects.com/
+// Copyright © ZZZ Projects Inc. 2014 - 2016. All rights reserved.
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Z.Collections.Test
+{
+    [TestClass]
+    public class System_Collections_Generic_IList_T_Shuffle
+    {
+        [TestMethod]
+        public void Shuffle()
+        {
+            // Input
+            var intList = new List<int>() { 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20 };
+
+            // Examples
+            var example1 = new List<int>(intList);
+            var example2 = new List<int>(intList);
+            var example3 = new List<int>(intList);
+            var example4 = new List<int>(intList);
+            var example5 = new List<int>(intList);
+
+            //Shuffle and pack results
+            example1.Shuffle();
+            example2.Shuffle();
+            example3.Shuffle();
+            example4.Shuffle();
+            example5.Shuffle();
+
+            var shuffledResults = new List<List<int>> {example1, example2, example3, example4, example5}; 
+
+            // Unit Test
+            Assert.IsTrue(shuffledResults.All(e=> e.Count() == 20), "The shuffle should't change the collection length");
+            Assert.IsFalse(shuffledResults.Contains(intList), "The input collection should not be contained in shuffled results");
+            Assert.IsTrue(shuffledResults.Distinct().Count() == shuffledResults.Count, "The shuffled results should be unique");
+        }
+    }
+}

test/Z.Collections.Test/Z.Collections.Test.csproj

@@ -78,6 +78,7 @@
     <Compile Include="System.Collections.Generic.ICollection[T]\ICollection[T].RemoveRangeIf.cs" />
     <Compile Include="System.Collections.Generic.ICollection[T]\ICollection[T].RemoveRangeIfContains.cs" />
     <Compile Include="System.Collections.Generic.ICollection[T]\ICollection[T].RemoveWhere.cs" />
+    <Compile Include="System.Collections.Generic.IList[T]\IList[T].Shuffle.cs" />
     <Compile Include="System.Collections.Generic.IList[T]\IList[T].Swap.cs" />
     <Compile Include="System.Collections.Generic.IDictionary[string, object]\IDictionary[string, object].ToExpando.cs" />
     <Compile Include="System.Collections.Generic.IDictionary[string, string]\IDictionary[string, string].ToNameValueCollection.cs" />