IndexOutOfRangeException in the command line parsor when run from GitHub Actions.

[AraHaan]

Describe the bug

Currently in one of my repositories I tried to get the MTP to work with xunit.v3 when running with .NET SDK 10.0.200 in GitHub Actions, I saw someone was able to use it with 10.0.201 so I tried that on my repository. However this happens on my repository as soon as my action goes to run dotnet build -c Release --no-build on the tests which runs the tests and results in a failure to run the identify & run my tests.

Locally when I use my .NET 11 daily build SDK I am unable to reproduce this issue and it is annoying me greatly.

The failed build: https://github.com/Elskom/IDisposableGenerator/actions/runs/23832789717/job/69469814486?pr=51
the PR: Elskom/IDisposableGenerator#51

Version used

The latest version that xunit.v3 references and the one that .NET 10 SDK v10.0.201 uses.

Steps To Reproduce

1. add reference to xunit.v3.
2. add a global.json which only enables MTP.
3. Reference 10.0.201 .NET SDK with my GitHub Action:

      - name: Install latest .NET 10 SDK
        uses: Elskom/setup-latest-dotnet@main
        with:
          SDK_VERSION: '10.0.201'
          RUNTIME_VERSIONS: ''

Expected behavior

For the tests to run and pass.

Actual behavior

no tests are run at all.

Additional context

The GitHub Action I made basically uses the dotnet-install scripts to install the .NET SDK I want into GitHub actions which is great for when I sometimes want to include the daily preview .NET SDK builds in some of my CI workflows.

[Youssef1313]

The split here is producing an empty arg at the end.

I think we then try to check if it starts with - here and it then throws IndexOufOfRangeException.

In all cases, an IndexOutOfRangeException isn't expected. Whether or not this should be considered as a parse error is something I need to validate. I'll do a quick experiment with System.CommandLine. But it's likely that we should skip empty arguments altogether.

[AraHaan]

https://github.com/Elskom/build-dotnet/blob/main/index.js#L41-L43
Yeah, you are correct it does put an empty arg at the end on my action.

[Youssef1313]

I double checked System.CommandLine. In this case, the empty string gets added to unmatched tokens. Whether or not it's an error is dependent on TreatUnmatchedTokensAsErrors (defaulting to true).

I think we should produce an error here, but something better than IndexOufOfRangeException for sure.

[Youssef1313]

#7648 will eliminate the exception in favor of a better error message. But you will still need to avoid the empty string in arguments.