Possible issue with Microsoft Fakes

[avivanoff]

A project that uses MSTest.Sdk/3.7.0 and EnableMicrosoftTestingExtensionsFakes set to true has issues execution tests that use fakes. Partial trace output:

  Message:
Test method TestMethod1 threw exception: 
Microsoft.QualityTools.Testing.Fakes.UnitTestIsolation.UnitTestIsolationException: Failed to resolve profiler path from COR_PROFILER_PATH and COR_PROFILER environment variables.

  Stack Trace: 
IntelliTraceInstrumentationProvider.ResolveProfilerPath()
IntelliTraceInstrumentationProvider.Initialize()
UnitTestIsolationRuntime.InitializeUnitTestIsolationInstrumentationProvider()
ShimRuntime.CreateContext()

Unfortunately, I was not able to create a project to reproduce the issue.

[avivanoff]

Some additional observations:

• Test project targets .NET Framework 4.8.
• Running EXE directly results in the same error.
• Running the tests using vstest.console.exe has no issues.
• Converting back to non-MSTest.Sdk works as expected.

[avivanoff]

Finally, I was able to create a sample project.

[drognanar]

Looking at the sample the <PlatformTarget>AnyCPU</PlatformTarget> portion of the csproj is causing issues.

When specified, the <RuntimeIdentifier> property is not automatically resolved via the .NET SDK. As a result, NuGet will not restore the necessary native Fakes dlls to the bin folder.

Removing <PlatformTarget>AnyCPU</PlatformTarget> or for instance explicitly setting <RuntimeIdentifier>win-x64</RuntimeIdentifier> makes the NuGet native dll files get copied to the bin folder (such as FakesInstrumentationProfiler_x64.config, Microsoft.QualityTools.Testing.Fakes.dll, Microsoft.QualityTools.Testing.Fakes.Instrumentation_x64.dll, Microsoft.Testing.Extensions.Fakes.dll) and the tests run successfully.

The reason why this is working with vstest.console (non-MSTest.SDK) is that it dynamically loads the Fakes libraries from C:\ProgramFiles, whereas the testing platform is designed to be self-contained and all of the libraries needed to run Fakes are expected to be in the bin folder instead.

[Evangelink]

@drognanar Thanks for the investigation. Would it be possible to update the Fakes extension doc page?

[drognanar]

@Evangelink it makes sense to add an FAQ entry as the same issue impacts code coverage, i.e. in this configuration the coverage file generated by running testProject.exe --coverage will be empty, since the code coverage native binaries are not copied into the bin folder.

[avivanoff]

@drognanar, @Evangelink, looks like the SDK-style projects have problems with .NET 4.8 targeting. If you change the target framework in the sample project to net8.0 it works.

[avivanoff]

@drognanar, @Evangelink, removing <PlatformTarget>AnyCPU</PlatformTarget> results in another issue: you cannot build for multiple platforms anymore. The reason is that fake assemblies are generated in FakesAssemblies folder. So if I build x64 first, the generated assemblies will be x64, and subsequent build of ARM64 or x86 will fail.