Unit Testing Works in VSCode on Windows but not Linux - linux

Question

I'm having trouble debugging Xunit unittests in .NET6 running on Ubuntu 20.04 in VSCode (1.66.2). These run in VisualStudio and VSCode in Windows. I can run (not debug) the tests in Linux from the CLI or the .NET Core Test Explorer extension.
If I try to debug the unittest with the context menu or the little magic command attribute that is placed above the unittest method declaration, I get an error:
Failed to start debugger:
"System.InvalidOperationException: The debugger could not be started
at OmniSharp.DotNetTest.Services.DebugTestService.Handle
(OmniSharp.DotNetTest.Models.DebugTestGetStartInfoRequest request) [0x00050] in <9d87b466e5a04dffb95becc0b4dfd560>:0
at OmniSharp.Endpoint.Exports.RequestHandlerExportHandler`2[TRequest,TResponse].Handle (TRequest request) [0x00000] in <3d93fabea6954f4ba147450b0cf4332a>:0
at OmniSharp.Endpoint.EndpointHandler`2[TRequest,TResponse].GetFirstNotEmptyResponseFromHandlers (OmniSharp.Endpoint.Exports.ExportHandler`2[TRequest,TResponse][] handlers, TRequest request) [0x00022] in <3d93fabea6954f4ba147450b0cf4332a>:0
at OmniSharp.Endpoint.EndpointHandler`2[TRequest,TResponse].HandleRequestForLanguage (System.String language, TRequest request, OmniSharp.Protocol.RequestPacket packet) [0x00163] in <3d93fabea6954f4ba147450b0cf4332a>:0
at OmniSharp.Endpoint.EndpointHandler`2[TRequest,TResponse].Process (OmniSharp.Protocol.RequestPacket packet, OmniSharp.Endpoint.LanguageModel model, Newtonsoft.Json.Linq.JToken requestObject) [0x0024b] in <3d93fabea6954f4ba147450b0cf4332a>:0
at OmniSharp.Stdio.Host.HandleRequest (System.String json, Microsoft.Extensions.Logging.ILogger logger) [0x000f3] in <2584067dfcea42a69c19a025cfbc4799>:0 "
I also see this in the OUTPUT pane:
/usr/share/dotnet/sdk/6.0.202/Microsoft.Common.CurrentVersion.targets(4650,5): error MSB3883: Unexpected exception: [/home/danielp/Source/Experiments/LibAndTest/Library/Library.csproj]
/usr/share/dotnet/sdk/6.0.202/Microsoft.Common.CurrentVersion.targets(4650,5): error : DirectoryNotFoundException: Could not find a part of the path '/home/danielp/Source/Experiments/LibAndTest/Library/bin/Debug/net6.0/ref/Library.dll'. [/home/danielp/Source/Experiments/LibAndTest/Library/Library.csproj]
/usr/share/dotnet/sdk/6.0.202/Microsoft.Common.CurrentVersion.targets(4650,5): error : at Interop.ThrowExceptionForIoErrno(ErrorInfo errorInfo, String path, Boolean isDirectory, Func`2 errorRewriter) [/home/danielp/Source/Experiments/LibAndTest/Library/Library.csproj]
/usr/share/dotnet/sdk/6.0.202/Microsoft.Common.CurrentVersion.targets(4650,5): error : at Microsoft.Win32.SafeHandles.SafeFileHandle.Open(String path, OpenFlags flags, Int32 mode) [/home/danielp/Source/Experiments/LibAndTest/Library/Library.csproj]
/usr/share/dotnet/sdk/6.0.202/Microsoft.Common.CurrentVersion.targets(4650,5): error : at Microsoft.Win32.SafeHandles.SafeFileHandle.Open(String fullPath, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize) [/home/danielp/Source/Experiments/LibAndTest/Library/Library.csproj]
/usr/share/dotnet/sdk/6.0.202/Microsoft.Common.CurrentVersion.targets(4650,5): error : at System.IO.FileSystem.CopyFile(String sourceFullPath, String destFullPath, Boolean overwrite) [/home/danielp/Source/Experiments/LibAndTest/Library/Library.csproj]
/usr/share/dotnet/sdk/6.0.202/Microsoft.Common.CurrentVersion.targets(4650,5): error : at System.IO.File.Copy(String sourceFileName, String destFileName, Boolean overwrite) [/home/danielp/Source/Experiments/LibAndTest/Library/Library.csproj]
/usr/share/dotnet/sdk/6.0.202/Microsoft.Common.CurrentVersion.targets(4650,5): error : at Microsoft.CodeAnalysis.BuildTasks.CopyRefAssembly.Copy() [/home/danielp/Source/Experiments/LibAndTest/Library/Library.csproj]
/usr/share/dotnet/sdk/6.0.202/Microsoft.Common.CurrentVersion.targets(4650,5): error : [/home/danielp/Source/Experiments/LibAndTest/Library/Library.csproj]
What I find interesting here is that it keeps looking for referenced dlls in ...Debug/net6.0/ref/Library.dll' and there is no build output binary placed there much less a folder called ref.
For now, I can debug w/ a console app, but it sure seems strange that this works so well in Windows but not Linux. However, now that I say that out loud: it seems like it shouldn't be that surprising.
Lastly, I did try debugging mstest unittests w/ the same results.

Answer 1

I figured it out! But only because I found this other answered question:
Cannot Run or Debug C# tests with CodeLens in VSCode
Because I'm running .NET 6, the Omnisharp extension needed a settings change:
Open your VSCode extensions w/ the icon on the left
Search for Omnisharp in the text box
Click the gear icon and choose Extension Settings from the resulting context menu
Up top in the search bar that is revealed in the settings page, append (w/ a space) modern so that the search bar contains #ext:ms-dotnettools.csharp modern
You will see a checkbox labeled Omnisharp: Use Modern Net.
Make sure this is checked.
I had to restart VSCode and allow the extension to do a download
After that it works.