Incremental Test

Incremental Test Runner for dotnet.Tests

Prerequisites

• A full build must have been completed at least once (via build.cmd or build.sh) so that the redist SDK layout exists at artifacts\bin\redist\Debug\dotnet\sdk\<version>\.
• The repo-local .dotnet SDK must match the version expected by the test projects. If the runtime or SDK version is out of date (e.g., test build fails with a missing framework error), run .\restore.cmd (or ./restore.sh on macOS/Linux) to download the correct SDK into .dotnet.
• This workflow uses Windows/PowerShell commands and paths. On macOS/Linux, substitute forward slashes and use cp instead of Copy-Item.

Workflow

Step 1: Identify modified projects

Determine which projects have been modified. Use context from:

• The files you just edited in this session.
• Or git status/git diff to find changed .cs files and map them to their .csproj projects.

Step 2: Build modified projects

Build each modified project individually using the repo-local dotnet:

.\.dotnet\dotnet build <path-to-project.csproj> -c Debug

For example:

.\.dotnet\dotnet build src\Cli\Microsoft.DotNet.Cli.Utils\Microsoft.DotNet.Cli.Utils.csproj -c Debug

If the dotnet CLI project itself was modified, build it:

.\.dotnet\dotnet build src\Cli\dotnet\dotnet.csproj -c Debug

Step 3: Copy output DLLs to the redist SDK layout

Discover the SDK version directory name:

$sdkVersion = (Get-ChildItem artifacts\bin\redist\Debug\dotnet\sdk -Directory | Sort-Object LastWriteTime -Descending | Select-Object -First 1).Name

For each modified project, copy its output DLL (and any satellite assemblies) from the project's build output to the redist SDK directory:

Source: artifacts\bin\<ProjectName>\Debug\net10.0\<AssemblyName>.dll
Target: artifacts\bin\redist\Debug\dotnet\sdk\<version>\

For example:

Copy-Item artifacts\bin\Microsoft.DotNet.ProjectTools\Debug\net10.0\Microsoft.DotNet.ProjectTools.dll artifacts\bin\redist\Debug\dotnet\sdk\$sdkVersion\
Copy-Item artifacts\bin\Microsoft.DotNet.Cli.Utils\Debug\net10.0\Microsoft.DotNet.Cli.Utils.dll artifacts\bin\redist\Debug\dotnet\sdk\$sdkVersion\

The dotnet project is special — it builds into artifacts\bin\dotnet\Debug\net10.0\ and its dotnet.dll must be copied to the SDK directory:

Copy-Item artifacts\bin\dotnet\Debug\net10.0\dotnet.dll artifacts\bin\redist\Debug\dotnet\sdk\$sdkVersion\

Important notes:

• For typical incremental edits, only copy DLLs that are already present in the target directory. If your change introduces a new shipped assembly or moves assemblies, you will need a full build.cmd/build.sh to update the layout correctly.
• Some projects multi-target (e.g., net10.0 and net472). Always use the net10.0 output.
• If localization resource DLLs were changed (in subdirectories like cs\, de\, etc.), copy those too.

Step 4: Run the tests

Invoke the run-tests skill for test/dotnet.Tests/dotnet.Tests.csproj with a filter for the affected tests. It builds the test project incrementally and retains detailed output, a TRX, and a binlog.

Common project paths