From e66d0da4e32c0d65f716ddd7f8db77be384ff07d Mon Sep 17 00:00:00 2001
From: Arnaud Van Herck <me@nobody.com>
Date: Wed, 7 Oct 2026 12:42:38 +0200
Subject: [PATCH] fix(tool): detect dotnet packs cross-platform

---
 CHANGELOG.md                                  |  4 +++
 .../Tool/ReflectionContextHelperTests.cs      | 36 +++++++++++++++++++
 .../TypeContractor.Tests.csproj               |  1 +
 TypeContractor.Tool/Program.cs                |  4 +--
 .../ReflectionContextHelper.cs                |  7 +++-
 .../TypeContractor.Tool.csproj                |  4 +++
 6 files changed, 53 insertions(+), 3 deletions(-)
 create mode 100644 TypeContractor.Tests/Tool/ReflectionContextHelperTests.cs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 10c09b1..6c4a053 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Detect the dotnet packs folder on macOS and Linux
+
 ## [0.22.1] - 2026-08-23
 
 ### Fixed
diff --git a/TypeContractor.Tests/Tool/ReflectionContextHelperTests.cs b/TypeContractor.Tests/Tool/ReflectionContextHelperTests.cs
new file mode 100644
index 0000000..6a1b434
--- /dev/null
+++ b/TypeContractor.Tests/Tool/ReflectionContextHelperTests.cs
@@ -0,0 +1,36 @@
+using TypeContractor.Tool;
+
+namespace TypeContractor.Tests.Tool
+{
+	public class ReflectionContextHelperTests
+	{
+		[Fact]
+		public void GetNetCorePack_Joins_Pack_Path_Without_Backslash()
+		{
+			var tempRoot = Path.Combine(Path.GetTempPath(), "typecontractor-" + Guid.NewGuid());
+			try
+			{
+				var expected = Path.Combine(tempRoot, "Microsoft.NETCore.App.Ref", "10.0.1", "ref", "net10.0");
+				Directory.CreateDirectory(expected);
+
+				var result = ReflectionContextHelper.GetNetCorePack(tempRoot, "Microsoft.NETCore.App.Ref", 10);
+
+				result.Should().Be(expected);
+			}
+			finally
+			{
+				if (Directory.Exists(tempRoot))
+					Directory.Delete(tempRoot, recursive: true);
+			}
+		}
+
+		[Fact]
+		public void GetDefaultPacksPath_Exists_And_Contains_NetCore_Ref_Pack()
+		{
+			var packsPath = ReflectionContextHelper.GetDefaultPacksPath();
+
+			Directory.Exists(packsPath).Should().BeTrue($"expected default packs path '{packsPath}' to exist");
+			Directory.Exists(Path.Combine(packsPath, "Microsoft.NETCore.App.Ref")).Should().BeTrue($"expected '{packsPath}' to contain 'Microsoft.NETCore.App.Ref'");
+		}
+	}
+}
diff --git a/TypeContractor.Tests/TypeContractor.Tests.csproj b/TypeContractor.Tests/TypeContractor.Tests.csproj
index 5b73865..9a224d3 100644
--- a/TypeContractor.Tests/TypeContractor.Tests.csproj
+++ b/TypeContractor.Tests/TypeContractor.Tests.csproj
@@ -34,6 +34,7 @@
 
 	<ItemGroup>
 		<ProjectReference Include="..\TypeContractor\TypeContractor.csproj" />
+		<ProjectReference Include="..\TypeContractor.Tool\TypeContractor.Tool.csproj" />
 	</ItemGroup>
 
 </Project>
diff --git a/TypeContractor.Tool/Program.cs b/TypeContractor.Tool/Program.cs
index 7af0500..b47c8a5 100644
--- a/TypeContractor.Tool/Program.cs
+++ b/TypeContractor.Tool/Program.cs
@@ -67,8 +67,8 @@
 
 var packsOptions = new Option<string>("--packs-path")
 {
-	DefaultValueFactory = (arg) => config.GetStringWithFallback("packs-path", @"C:\Program Files\dotnet\packs\"),
-	Description = "Path where dotnet is installed and reference assemblies can be found.",
+	DefaultValueFactory = (arg) => config.GetStringWithFallback("packs-path", ReflectionContextHelper.GetDefaultPacksPath()),
+	Description = "Path where dotnet reference packs can be found. Defaults to the packs folder of the active .NET installation.",
 };
 
 var dotnetVersionOptions = new Option<int>("--dotnet-version")
diff --git a/TypeContractor.Tool/ReflectionContextHelper.cs b/TypeContractor.Tool/ReflectionContextHelper.cs
index 45abb5a..544be97 100644
--- a/TypeContractor.Tool/ReflectionContextHelper.cs
+++ b/TypeContractor.Tool/ReflectionContextHelper.cs
@@ -44,7 +44,7 @@ internal static PathAssemblyResolver GetResolver(string packPath, int dotnetVers
 
 	internal static string? GetNetCorePack(string packPath, string packName, int dotnetVersion)
 	{
-		var packPrefix = @$"{packPath}\{packName}";
+		var packPrefix = Path.Combine(packPath, packName);
 		if (!Directory.Exists(packPrefix))
 			return null;
 
@@ -59,4 +59,9 @@ internal static PathAssemblyResolver GetResolver(string packPath, int dotnetVers
 
 		return packDirectory;
 	}
+
+	internal static string GetDefaultPacksPath() =>
+		Path.GetFullPath(Path.Combine(
+			RuntimeEnvironment.GetRuntimeDirectory(),
+			"..", "..", "..", "packs"));
 }
diff --git a/TypeContractor.Tool/TypeContractor.Tool.csproj b/TypeContractor.Tool/TypeContractor.Tool.csproj
index 7b39d1b..7e8ff39 100644
--- a/TypeContractor.Tool/TypeContractor.Tool.csproj
+++ b/TypeContractor.Tool/TypeContractor.Tool.csproj
@@ -33,6 +33,10 @@
 	  <ProjectReference Include="..\TypeContractor\TypeContractor.csproj" />
 	</ItemGroup>
 
+	<ItemGroup>
+		<InternalsVisibleTo Include="TypeContractor.Tests" />
+	</ItemGroup>
+
 	<ItemGroup>
 		<None Include="..\LICENSE" Pack="true" PackagePath="\" />
 		<None Include="..\README.md" Pack="true" PackagePath="\" />