From 991cfdd5c31d840652e3d64142b5e39d20859728 Mon Sep 17 00:00:00 2001
From: Vladimir Pecanac <vladimir.pecanac@gmail.com>
Date: Sun, 18 Oct 2026 14:19:21 +0200
Subject: [PATCH] Type Checking and Casting: retarget to .NET 10, update test
 packages, add tests

Both projects move to net10.0 and the test packages to Microsoft.NET.Test.Sdk 18.11.0, xunit 2.9.3, xunit.runner.visualstudio 4.0.1 and coverlet.collector 10.1.0. The is-operator test declares its values as object, which removes the CS0183 and CS0184 warnings. Two tests added: is against GetType() on a derived instance, and an overflowing long cast in unchecked and checked contexts.
---
 .../TypeCheckingAndCastingInCSharp.Tests.csproj | 10 +++++-----
 .../TypeConversionTests.cs                      | 11 +++++++++++
 .../TypeTestingTests.cs                         | 17 +++++++++++++++--
 .../TypeCheckingAndCastingInCSharp.csproj       |  2 +-
 4 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeCheckingAndCastingInCSharp.Tests.csproj b/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeCheckingAndCastingInCSharp.Tests.csproj
index 97a013ffb1..1c727d12b4 100644
--- a/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeCheckingAndCastingInCSharp.Tests.csproj
+++ b/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeCheckingAndCastingInCSharp.Tests.csproj
@@ -1,20 +1,20 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <Nullable>enable</Nullable>
 
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
-    <PackageReference Include="xunit" Version="2.4.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.11.0" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="4.0.1">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
-    <PackageReference Include="coverlet.collector" Version="3.1.0">
+    <PackageReference Include="coverlet.collector" Version="10.1.0">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
diff --git a/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeConversionTests.cs b/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeConversionTests.cs
index b29e572e23..6bbe2e813b 100644
--- a/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeConversionTests.cs
+++ b/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeConversionTests.cs
@@ -41,6 +41,17 @@ public void WhenAssigningValuesToOtherType_ThenUseCastExpressionForExplicitConve
             Assert.Equal(10, number);
         }
 
+        [Fact]
+        public void WhenCastingAnOverflowingValue_ThenUncheckedWrapsAndCheckedThrows()
+        {
+            // arrange
+            long tooBig = long.MaxValue;
+
+            // act & assert
+            Assert.Equal(-1, unchecked((int)tooBig));
+            Assert.Throws<OverflowException>(() => checked((int)tooBig));
+        }
+
         [Fact]
         public void WhenAssigningBaseToDerivedType_ThenUseCastExpressionForExplicitConversion()
         {
diff --git a/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeTestingTests.cs b/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeTestingTests.cs
index 009754e2f5..4634143ec8 100644
--- a/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeTestingTests.cs
+++ b/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.Tests/TypeTestingTests.cs
@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using TypeCheckingAndCastingInCSharp.Models;
 using Xunit;
 
 namespace TypeCheckingAndCastingInCSharp.Tests
@@ -94,14 +95,26 @@ public void WhenTypeTestingAtRunTime_ThenUseGeTypeAndTypeof()
         [Fact]
         public void WhenTypeCheckingValues_ThenIsOperatorReturnsBoolean()
         {
-            int number = 16;
-            string name = "John Smith";
+            object number = 16;
+            object name = "John Smith";
 
             Assert.True(number is int);     // true
             Assert.True(name is string);    // true
             Assert.False(number is bool);   // false
         }
 
+        [Fact]
+        public void WhenCheckingADerivedInstance_ThenIsMatchesTheBaseTypeAndGetTypeDoesNot()
+        {
+            // arrange
+            Animal animal = new Horse();
+
+            // act & assert
+            Assert.True(animal is Animal);                       // compatible type
+            Assert.False(animal.GetType() == typeof(Animal));    // not the exact type
+            Assert.True(animal.GetType() == typeof(Horse));      // the exact type
+        }
+
         [Fact]
         public void WhenCastingValues_ThenUseTypePatterns()
         {
diff --git a/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.csproj b/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.csproj
index 74abf5c976..dfb40caafc 100644
--- a/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.csproj
+++ b/csharp-basic-topics/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp/TypeCheckingAndCastingInCSharp.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>