How to clone a list: retarget net10.0, collection expression and GetRange, remove broken ToppingsList clone

Move both projects from net7.0 to net10.0 and update the test stack (xunit 2.9.3, runner 4.0.0, Test.Sdk 18.10.1, coverlet 10.0.1, FluentAssertions 7.2.2).

Remove ToppingsList<T> and its test: its Clone() called MemberwiseClone(), which copies the private backing array by reference, so the clone shared storage with the original and was not a clone at all.

Add a collection-expression clone and a GetRange clone with tests, build the copy-constructor deep copy as a one-line projection, and add a test proving the projected clone keeps its toppings after the original is cleared.

Fix the ConverAll typo in the console output, make Pizza.Name and Pizza.Toppings required with [SetsRequiredMembers] on the copy constructor, and use First instead of FirstOrDefault. The folder now builds with 0 warnings and runs 11 of 11 tests.

Author: vladimir-pecanac-main

collections-lists/HowToCloneAList/HowToCloneAList.Tests/HowToCloneAList.Tests.csproj

@@ -1,22 +1,22 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
 
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="FluentAssertions" Version="6.9.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.3.2" />
-    <PackageReference Include="xunit" Version="2.4.2" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">
+    <PackageReference Include="FluentAssertions" Version="7.2.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.10.1" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="4.0.0">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
-    <PackageReference Include="coverlet.collector" Version="3.1.2">
+    <PackageReference Include="coverlet.collector" Version="10.0.1">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>

collections-lists/HowToCloneAList/HowToCloneAList.Tests/PizzaTests.cs

@@ -1,4 +1,4 @@
-using FluentAssertions;
+using FluentAssertions;
 
 namespace HowToCloneAList.Tests
 {
@@ -60,5 +60,29 @@ public void GivenAValidPizza_WhenToStringMethodIsInvoked_ThenToStringMethodMetho
 
             expectedOutput.Should().Be(margherita.ToString());
         }
+
+        [Fact]
+        public void GivenAListOfPizzas_WhenProjectedThroughTheCopyConstructor_ThenTheCloneKeepsItsToppings()
+        {
+            var pizzas = new List<Pizza>
+            {
+                new Pizza
+                {
+                    Name = "Margherita",
+                    Toppings = new List<string>
+                    {
+                        "Mozzarella",
+                        "Olive oil",
+                        "Basil"
+                    }
+                }
+            };
+
+            List<Pizza> clone = [.. pizzas.Select(p => new Pizza(p))];
+
+            pizzas[0].Toppings.Clear();
+
+            clone[0].Toppings.Should().HaveCount(3);
+        }
     }
-}
+}

collections-lists/HowToCloneAList/HowToCloneAList.Tests/Tests.cs

@@ -56,5 +56,27 @@ public void GivenAValidList_WhenConvertAllMethodIsInvoked_ThenConvertAllMethodRe
 
             listClone.Should().BeEquivalentTo(list);
         }
+
+        [Fact]
+        public void GivenAValidList_WhenACollectionExpressionIsUsed_ThenTheCollectionExpressionReturnsNewListInstance()
+        {
+            var list = new List<string> { "one", "two", "three" };
+
+            List<string> listClone = [.. list];
+
+            listClone.Should().BeEquivalentTo(list);
+            listClone.Should().NotBeSameAs(list);
+        }
+
+        [Fact]
+        public void GivenAValidList_WhenGetRangeMethodIsInvoked_ThenGetRangeMethodReturnsNewListInstance()
+        {
+            var list = new List<string> { "one", "two", "three" };
+
+            var listClone = list.GetRange(0, list.Count);
+
+            listClone.Should().BeEquivalentTo(list);
+            listClone.Should().NotBeSameAs(list);
+        }
     }
 }

collections-lists/HowToCloneAList/HowToCloneAList.Tests/ToppingsListTests.cs

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>

collections-lists/HowToCloneAList/HowToCloneAList/HowToCloneAList.csproj

@@ -1,19 +1,22 @@
-namespace HowToCloneAList
+using System.Diagnostics.CodeAnalysis;
+
+namespace HowToCloneAList
 {
     public class Pizza : ICloneable
     {
         public Pizza()
         {
         }
 
+        [SetsRequiredMembers]
         public Pizza(Pizza pizza)
         {
             Name = pizza.Name;
             Toppings = pizza.Toppings.ToList();
         }
 
-        public string Name { get; set; }
-        public List<string> Toppings { get; set; }
+        public required string Name { get; set; }
+        public required List<string> Toppings { get; set; }
 
         public object Clone()
         {

collections-lists/HowToCloneAList/HowToCloneAList/Pizza.cs

@@ -24,22 +24,18 @@ static void Main(string[] args)
             var toppingsClonedWithConvertAll = toppings
                 .ConvertAll(new Converter<string, string>(x => x));
 
-            var customToppingsList = new ToppingsList<string>
-            {
-                "Mozzarella",
-                "Olive oil",
-                "Basil"
-            };
+            List<string> toppingsClonedWithCollectionExpression = [.. toppings];
 
-            var toppingsClonedWithICloneable = (ToppingsList<string>)customToppingsList.Clone();
+            var toppingsClonedWithGetRange = toppings.GetRange(0, toppings.Count);
 
             Console.WriteLine("Original list: " + string.Join(", ", toppings));
             Console.WriteLine("Cloned with Constructor: " + string.Join(", ", toppingsClonedWithConstructor));
             Console.WriteLine("Cloned with CopyTo: " + string.Join(", ", toppingsClonedWithCopyTo));
             Console.WriteLine("Cloned with AddRange: " + string.Join(", ", toppingsClonedWithAddRange));
             Console.WriteLine("Cloned with ToList: " + string.Join(", ", toppingsClonedWithToList));
-            Console.WriteLine("Cloned with ConverAll: " + string.Join(", ", toppingsClonedWithConvertAll));
-            Console.WriteLine("Cloned with ICloneable: " + string.Join(", ", toppingsClonedWithICloneable));
+            Console.WriteLine("Cloned with ConvertAll: " + string.Join(", ", toppingsClonedWithConvertAll));
+            Console.WriteLine("Cloned with a collection expression: " + string.Join(", ", toppingsClonedWithCollectionExpression));
+            Console.WriteLine("Cloned with GetRange: " + string.Join(", ", toppingsClonedWithGetRange));
 
             var pizzas = new List<Pizza>
             {
@@ -74,15 +70,10 @@ static void Main(string[] args)
                 pizzasClonedWithICloneable.Add((Pizza)pizza.Clone());
             }
 
-            var pizzasClonedWithCopyConstructor = new List<Pizza>();
-
-            foreach (var pizza in pizzas)
-            {
-                pizzasClonedWithCopyConstructor.Add(new Pizza(pizza));
-            }
+            List<Pizza> pizzasClonedWithCopyConstructor = [.. pizzas.Select(p => new Pizza(p))];
 
             var margherita = pizzas
-                .FirstOrDefault(x => x.Name == "Margherita");
+                .First(x => x.Name == "Margherita");
 
             margherita.Toppings.Clear();