Building .NET projects using the Microsoft.Build.Traversal SDK

Continuous integration scripts typically run dotnet build mysolution.sln and dotnet test mysolution.sln. Consider a solution with multiple class libraries and a few WPF projects, where the goal is to create NuGet packages and run tests on Windows, Linux, and Mac. The problem is that WPF projects cannot be built on Linux or Mac, so dotnet build fails on those platforms.

One approach is to create a new .sln file or use a filtered solution (.slnf) to exclude WPF projects when building on non-Windows systems. The downside is that the filtered solution must be kept up to date whenever a new project is added.

A better approach is to use the Microsoft.Build.Traversal SDK. This custom SDK lets you select which projects to build or test using MSBuild syntax, including glob patterns. To use the SDK, create a global.json file at the root of your repository with the following content:

// https://learn.microsoft.com/en-us/dotnet/core/tools/global-json?WT.mc_id=DT-MVP-5003978
{
  "sdk": {
    "version": "5.0.201",
    "rollForward": "patch"
  },
  "msbuild-sdks": {
    "Microsoft.Build.Traversal": "3.0.3"
  }
}

Then, create a project file named dirs.proj (any name works) with the following content:

<Project Sdk="Microsoft.Build.Traversal">
  <ItemGroup>
    <!-- Build all csproj and vbproj -->
    <ProjectReference Include="**/*.*proj" />
  </ItemGroup>

  <!-- Remove WPF projects when building on Linux or Mac -->
  <ItemGroup Condition="$([MSBuild]::IsOsPlatform('WINDOWS')) == false">
    <ProjectReference Remove="src/Meziantou.Framework.WPF/Meziantou.Framework.WPF.csproj" />
    <ProjectReference Remove="tests/Meziantou.Framework.WPF.Tests/Meziantou.Framework.WPF.Tests.csproj" />
  </ItemGroup>
</Project>

Finally, use the dotnet CLI to build, test, and pack the project. The SDK forwards the command to all referenced projects:

dotnet build dirs.proj --configuration Release /bl

dotnet test dirs.proj

dotnet pack dirs.proj

#Visual Studio integration

Currently, dirs.proj files cannot be opened in Visual Studio as a solution replacement. If you prefer to avoid .sln files, consider upvoting these issues:

• Open Microsoft.Build.Traversal project files as solutions
• [Discussion] Clean up sln (VisualStudio solution) files

#Additional resources

• Microsoft.Build.Traversal - GitHub

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