use SpecialFolder.UserProfile instead of USERPROFILE (#108559)

* use SpecialFolder.UserProfile instead of USERPROFILE

* Update PackageResolverTest.cs

* Update PackageResolverTest.cs

* Update src/libraries/Microsoft.Extensions.DependencyModel/tests/PackageResolverTest.cs

* Update PackageResolverTest.cs

---------

Co-authored-by: Viktor Hofer <[email protected]>

Author: kasperk81

src/libraries/Microsoft.Extensions.DependencyModel/src/Resolution/PackageCompilationAssemblyResolver.cs

@@ -19,7 +19,7 @@ public PackageCompilationAssemblyResolver()
         }
 
         public PackageCompilationAssemblyResolver(string nugetPackageDirectory)
-            : this(FileSystemWrapper.Default, new string[] { nugetPackageDirectory })
+            : this(FileSystemWrapper.Default, [nugetPackageDirectory])
         {
         }
 
@@ -46,32 +46,24 @@ internal static string[] GetDefaultProbeDirectories(IEnvironment environment)
 
             if (!string.IsNullOrEmpty(listOfDirectories))
             {
-                return listOfDirectories.Split(new char[] { Path.PathSeparator }, StringSplitOptions.RemoveEmptyEntries);
+                return listOfDirectories.Split([Path.PathSeparator], StringSplitOptions.RemoveEmptyEntries);
             }
 
             string? packageDirectory = environment.GetEnvironmentVariable("NUGET_PACKAGES");
 
             if (!string.IsNullOrEmpty(packageDirectory))
             {
-                return new string[] { packageDirectory };
+                return [packageDirectory];
             }
 
-            string? basePath;
-            if (environment.IsWindows())
-            {
-                basePath = environment.GetEnvironmentVariable("USERPROFILE");
-            }
-            else
-            {
-                basePath = environment.GetEnvironmentVariable("HOME");
-            }
+            string basePath = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
 
             if (string.IsNullOrEmpty(basePath))
             {
-                return new string[] { string.Empty };
+                return [string.Empty];
             }
 
-            return new string[] { Path.Combine(basePath, ".nuget", "packages") };
+            return [Path.Combine(basePath, ".nuget", "packages")];
         }
 
         public bool TryResolveAssemblyPaths(CompilationLibrary library, List<string>? assemblies)
@@ -102,7 +94,7 @@ public bool TryResolveAssemblyPaths(CompilationLibrary library, List<string>? as
 
         private static bool TryResolveFromPackagePath(IFileSystem fileSystem, CompilationLibrary library, string basePath, [MaybeNullWhen(false)] out IEnumerable<string> results)
         {
-            var paths = new List<string>();
+            List<string> paths = [];
 
             foreach (string assembly in library.Assemblies)
             {

src/libraries/Microsoft.Extensions.DependencyModel/tests/PackageResolverTest.cs

@@ -1,9 +1,11 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
 using System.Collections.Generic;
 using System.IO;
 using FluentAssertions;
+using Microsoft.DotNet.XUnitExtensions;
 using Microsoft.Extensions.DependencyModel.Resolution;
 using Xunit;
 using F = Microsoft.Extensions.DependencyModel.Tests.TestLibraryFactory;
@@ -26,31 +28,15 @@ public void ShouldUseEnvironmentVariableToGetDefaultLocation()
             result.Should().Contain(PackagesPath);
         }
 
-
-        [Fact]
-        public void ShouldUseNugetUnderUserProfileOnWindows()
-        {
-            var environment = EnvironmentMockBuilder.Create()
-                .SetIsWindows(true)
-                .AddVariable("USERPROFILE", "User Profile")
-                .AddAppContextData("PROBING_DIRECTORIES", string.Empty)
-                .Build();
-
-            var result = PackageCompilationAssemblyResolver.GetDefaultProbeDirectories(environment);
-            result.Should().Contain(Path.Combine("User Profile", ".nuget", "packages"));
-        }
-
-        [Fact]
-        public void ShouldUseNugetUnderHomeOnNonWindows()
+        [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotWindowsNanoServer))] // https://github.com/dotnet/runtime/issues/21430
+        public void ShouldUseNugetUnderUserProfile()
         {
             var environment = EnvironmentMockBuilder.Create()
-                .SetIsWindows(false)
-                .AddVariable("HOME", "User Home")
                 .AddAppContextData("PROBING_DIRECTORIES", string.Empty)
                 .Build();
 
             var result = PackageCompilationAssemblyResolver.GetDefaultProbeDirectories(environment);
-            result.Should().Contain(Path.Combine("User Home", ".nuget", "packages"));
+            result.Should().Contain(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".nuget", "packages"));
         }
 
         [Fact]