New IList<T> extension method - Swap

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

@@ -0,0 +1,29 @@
+// 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;
+
+public static partial class Extensions
+{
+    /// <summary>
+    /// An ICollection&lt;T&gt; extension method that swaps value only when it exists in a collection.
+    /// </summary>
+    /// <typeparam name="T">Generic type parameter.</typeparam>
+    /// <param name="this">The @this to act on.</param>
+    /// <param name="oldValue">The old value.</param>
+    /// <param name="newValue">The new value.</param>
+    /// <returns>
+    /// true if it succeeds, false if it fails.
+    /// </returns>
+    public static void Swap<T>(this ICollection<T> @this, T oldValue, T newValue)
+    {
+        if (@this.Contains(oldValue))
+        {
+            @this.Remove(oldValue);
+            @this.Add(newValue);
+        }
+    }
+}

src/Z.Collections/System.Collections.Generic.IList[T]/IList[T].Swap.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.Collections.Generic;
+
+public static partial class Extensions
+{
+    /// <summary>
+    /// An ICollection&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>
+    /// <param name="oldValue">The old value.</param>
+    /// <param name="newValue">The new value.</param>
+    /// <returns>
+    /// true if it succeeds, false if it fails.
+    /// </returns>
+    public static void Swap<T>(this IList<T> @this, T oldValue, T newValue)
+    {
+        var oldIndex = @this.IndexOf(oldValue);
+        while (oldIndex > 0)
+        {
+            @this.RemoveAt(oldIndex);
+            @this.Insert(oldIndex, newValue);
+            oldIndex = @this.IndexOf(oldValue);
+        }
+    }
+}

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].Swap.cs" />
     <Compile Include="System.Collections.Generic.ICollection[T]\ICollection[T].AddIf.cs" />
     <Compile Include="System.Collections.Generic.ICollection[T]\ICollection[T].AddIfNotContains.cs" />
     <Compile Include="System.Collections.Generic.ICollection[T]\ICollection[T].AddRange.cs" />
@@ -102,6 +103,7 @@
     <Compile Include="System.Collections.IDictionary\IDictionary.ToHashtable.cs" />
     <Compile Include="System.Collections.Specialized.NameValueCollection\NameValueCollection.ToDictionary.cs" />
   </ItemGroup>
+  <ItemGroup />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.

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

@@ -0,0 +1,60 @@
+// 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_Swap
+    {
+        [TestMethod]
+        public void Swap()
+        {
+            // Type
+            var stringList = new List<string>() { "Foo", "Bar", "Baz" };
+            var obj1 = new { Id = 1, Message = "Foo" };
+            var obj2 = new { Id= 2, Message = "Bar" };
+            var obj3 = new { Id = 3, Message = "Baz" };
+
+            // Examples
+            var example1 = new List<string>(stringList);
+            var example2 = new List<string>(stringList);
+            var example3 = new List<string>(stringList);
+            var example4 = new List<string>(stringList);
+            var example5 = new List<string>() {"Foo", "Bar", "Bar"};
+            var example6 = new List<object>() { obj1, obj2 };
+
+            //Swaps
+            example1.Swap("Baz", "NewBaz");
+            example2.Swap("NoValueFound", "NoBaz");
+            example3.Swap(null, "NothingChanged");
+            example4.Swap("Bar", "NewBar");
+            example5.Swap("Bar", "Baz");
+            example6.Swap(obj2, obj3);
+
+            // Expected results
+            var result1 = new List<string>() {"Foo", "Bar", "NewBaz"};
+            var result2 = new List<string>(stringList);
+            var result3 = new List<string>(stringList);
+            var result4 = example4.ElementAt(1).Equals("NewBar");
+            var result5 = example5.Contains("Bar");
+            var result6 = example6.Contains(obj3);
+
+            // Unit Test
+            Assert.IsTrue(example1.Contains("NewBaz"), "The collection should contain this value");
+            Assert.IsFalse(example2.Contains("NoBaz"), "The collection shouldn't contain this value");
+            Assert.IsTrue(example1.SequenceEqual(result1), "The collection should have the replaced value");
+            Assert.IsTrue(example2.SequenceEqual(result2), "The collection shouldn't have the replaced value");
+            Assert.IsTrue(example3.SequenceEqual(result3), "The collection shouldn't have the replaced value");
+            Assert.IsTrue(result4, "The item in a collection shouldn't change it's position");
+            Assert.IsFalse(result5, "All values should be swaped");
+            Assert.IsTrue(result6, "The object in a collection should be swaped");
+        }
+    }
+}

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].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" />
     <Compile Include="System.Collections.Generic.IDictionary[TKey,TValue]\IDictionary[TKey,TValue].AddIfNotContainsKey.cs" />