Test Explorer cannot find a generated test file (exception)

[mjvh80]

Summary: Cannot open Roslyn generated tests via Test Explorer

The Roslyn generator project looks like

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
    <LangVersion>latest</LangVersion>
    <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.12.0" PrivateAssets="all" />
  </ItemGroup>

</Project>

and something like

using Microsoft.CodeAnalysis;

namespace Generator
{
    [Generator]
    public class Generator : IIncrementalGenerator
    {
        public void Initialize(IncrementalGeneratorInitializationContext context) =>
            context.RegisterSourceOutput(context.CompilationProvider, (sourceCtx, _) =>
        {
            sourceCtx.AddSource("GeneratedTest.cs", """
            using System;
            using Microsoft.VisualStudio.TestTools.UnitTesting;

            namespace GeneratedTests
            {
                [TestClass]
                public sealed class GeneratedTest
                {
                    [TestMethod]
                    public void TestMethod()
                    {
                        Assert.IsTrue(true);
                    }
                }
            }
            """);
        });
    }
}

(of course in reality this actually generates something)

The consuming project looks like

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
    <PackageReference Include="MSTest" Version="3.8.1" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\Generator\Generator.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
  </ItemGroup>

</Project>

If I now click Run All Tests on the Runner project, the tests are found, and run correctly. However, clicking on the TestMethod in Test Explorer

leads to this exception seen in the Test Output window

[20/02/2025 11:32:04.319 AM]  Source location lookup for Source: D:\temp\Runner\bin\Debug\net8.0\Runner.dll by ManagedType: GeneratedTests.GeneratedTest and ManagedMethod: TestMethod
[20/02/2025 11:32:04.557 AM] [Error] System.ArgumentException: The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
   at EnvDTE.ItemOperations.OpenFile(String FileName, String ViewKind)
   at Microsoft.VisualStudio.TestWindow.VsHost.IOpenTargetExtensions.<OpenFileAsync>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.VisualStudio.TestWindow.VsHost.IOpenTargetExtensions.<OpenFileAsync>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.TestWindow.VsHost.IOpenTargetExtensions.<OpenAsync>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.TestWindow.Internal.TestWindowViewModel.<<OnNavigationRequested>b__140_1>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.TestWindow.Logging.ILoggerExtensions.<CallWithCatchAsync>d__12.MoveNext()
[20/02/2025 11:32:05.374 AM] [Error] System.ArgumentException: The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
   at EnvDTE.ItemOperations.OpenFile(String FileName, String ViewKind)
   at Microsoft.VisualStudio.TestWindow.VsHost.IOpenTargetExtensions.<OpenFileAsync>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.VisualStudio.TestWindow.VsHost.IOpenTargetExtensions.<OpenFileAsync>d__2.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.TestWindow.VsHost.IOpenTargetExtensions.<OpenAsync>d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.TestWindow.Internal.TestWindowViewModel.<<OnNavigationRequested>b__140_1>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.TestWindow.Logging.ILoggerExtensions.<CallWithCatchAsync>d__12.MoveNext()

and nothing happens.

Expected behavior: the generated source file is opened (I emit them if that matters, but possibly more is needed?).

Actual behavior: nothing happens

[nohwnd]

This is Test Explorer issue @AbhitejJohn please redirect this as appropriate.

[nohwnd]

@mjvh80 this is not the best repo to report this issue, if you post on https://developercommunity.visualstudio.com/home you will have a better luck getting this tracked by Test Explorer team. I tagged Abhitej above, so it is up to you if you decide to file it on visual studio, or keep it here. :)