VS2019 shouldn't write Warning "No test is available" when that's expected

In Visual Studio 2019, when I (re)build my C# project, the Tests section in the Output window shows the following warning:

[8/13/2019 9:58:08.397 AM Informational] ---------- Discovery started ----------
[8/13/2019 9:58:09.564 AM Warning] No test is available in H:\Foo\src\bin\Release\net461\Foo.dll. Make sure that test discoverer & executors are registered and platform & framework version settings are appropriate and try again.
[8/13/2019 9:58:09.612 AM Informational] ========== Discovery finished: 0 tests found (0:00:01.2086584) ==========

I have a separate project which contains my unit tests. Foo.dll will never contain tests. How can I avoid this assembly/project being scanned for tests and causing that warning message from being written?

Here is the full diagnostic log:

[8/13/2019 10:41:36.704 AM Diagnostic] Pausing Queue..., current operation is: no current operation
[8/13/2019 10:41:36.705 AM Diagnostic] Enqueue operation 'WaitForBuildOperation', hashcode:43196519 
[8/13/2019 10:41:36.705 AM Diagnostic] Operation left in the the queue: 1
[8/13/2019 10:41:36.705 AM Diagnostic] 	'WaitForBuildOperation', hashcode:43196519
[8/13/2019 10:41:36.705 AM Diagnostic] 

[8/13/2019 10:41:36.705 AM Diagnostic] Operation Dequeue : 'WaitForBuildOperation'
[8/13/2019 10:41:54.416 AM Diagnostic] Container Discoverer 'Microsoft.VisualStudio.TestWindow.Client.TestContainer.ProjectOutputContainerDiscoverer' has container changes
[8/13/2019 10:41:54.632 AM Diagnostic] test container discoverer executor://projectoutputcontainerdiscoverer/v1, discovered 1 containers
[8/13/2019 10:41:54.633 AM Diagnostic] Containers from 'Microsoft.VisualStudio.TestWindow.Client.TestContainer.ProjectOutputContainerDiscoverer' :
[8/13/2019 10:41:54.634 AM Diagnostic] 	H:\Foo\src\bin\Release\net461\Foo.dll
[8/13/2019 10:41:54.646 AM Diagnostic] Enqueue operation 'DiscoverSelectedOperation', hashcode:63023693 
[8/13/2019 10:41:54.646 AM Diagnostic] Operation left in the the queue: 1
[8/13/2019 10:41:54.646 AM Diagnostic] 	'DiscoverSelectedOperation', hashcode:63023693
[8/13/2019 10:41:54.646 AM Diagnostic] 

[8/13/2019 10:41:54.646 AM Diagnostic] Operation Dequeue : 'DiscoverSelectedOperation'
[8/13/2019 10:41:54.646 AM Diagnostic] DiscoveryOperation<DiscoverSelectedOperation> FinishedChangedCotainers, changed container count is 1
[8/13/2019 10:41:54.647 AM Diagnostic] Discovering the following containers :
[8/13/2019 10:41:54.647 AM Diagnostic] 	H:\Foo\src\bin\Release\net461\Foo.dll
[8/13/2019 10:41:54.653 AM Error] System.InvalidOperationException: The operation failed as details for project DotNetCore could not be loaded.
   at NuGet.PackageManagement.VisualStudio.NetCorePackageReferenceProject.GetPackageSpecsAsync(DependencyGraphCacheContext context)
   at NuGet.VisualStudio.VsPackageInstallerServices.<GetPackagesPathResolverAsync>d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at NuGet.VisualStudio.VsPackageInstallerServices.<>c__DisplayClass7_0.<<GetInstalledPackages>b__0>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.VisualStudio.Threading.JoinableTask.CompleteOnCurrentThread()
   at Microsoft.VisualStudio.Threading.JoinableTask`1.CompleteOnCurrentThread()
   at Microsoft.VisualStudio.Threading.JoinableTaskFactory.Run[T](Func`1 asyncMethod, JoinableTaskCreationOptions creationOptions)
   at NuGet.VisualStudio.VsPackageInstallerServices.GetInstalledPackages()
   at Microsoft.VisualStudio.TestWindow.Controller.UnitTestExtensionDiscoverer.GetNugetAdapters()
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.VisualStudio.Telemetry.WindowsErrorReporting.WatsonReport.GetClrWatsonExceptionInfo(Exception exceptionObject)
[8/13/2019 10:41:54.654 AM Informational] ---------- Discovery started ----------
[8/13/2019 10:41:55.056 AM Diagnostic] TelemetrySession: Creating the event: VS/UnitTest/TestWindow/Ext/RunSettingsService 
[8/13/2019 10:41:55.056 AM Diagnostic] Event:VS/UnitTest/TestWindow/Ext/RunSettingsService key: VS.UnitTest.TestWindow.RunSettingsService.Name value:VSTest Run Configuration
[8/13/2019 10:41:55.057 AM Diagnostic] TelemetrySession: Creating the event: VS/UnitTest/TestWindow/Ext/RunSettingsService 
[8/13/2019 10:41:55.057 AM Diagnostic] Event:VS/UnitTest/TestWindow/Ext/RunSettingsService key: VS.UnitTest.TestWindow.RunSettingsService.Name value:TestPropertySettingsForBoostAdapter
[8/13/2019 10:41:55.057 AM Diagnostic] TelemetrySession: Creating the event: VS/UnitTest/TestWindow/Ext/RunSettingsService 
[8/13/2019 10:41:55.057 AM Diagnostic] Event:VS/UnitTest/TestWindow/Ext/RunSettingsService key: VS.UnitTest.TestWindow.RunSettingsService.Name value:TestPropertySettingsForGoogleAdapter
[8/13/2019 10:41:55.058 AM Diagnostic] TelemetrySession: Creating the event: VS/UnitTest/TestWindow/Ext/RunSettings 
[8/13/2019 10:41:55.058 AM Diagnostic] Event:VS/UnitTest/TestWindow/Ext/RunSettings key: VS.UnitTest.TestWindow.RunSettings.Services value:3
[8/13/2019 10:41:55.063 AM Diagnostic] File timestamp changed from 8/13/2019 10:02:25 AM to 8/13/2019 10:41:51 AM for H:\Foo\src\bin\Release\net461\Foo.dll
[8/13/2019 10:41:55.099 AM Diagnostic] Grouped H:\Foo\src\bin\Release\net461\Foo.dll : (AnyCPU, Framework45, net461, )
[8/13/2019 10:41:55.100 AM Diagnostic] Test discovery settings for H:\Foo\src\bin\Release\net461\Foo.dll:
 <RunSettings>
  <RunConfiguration>
    <ResultsDirectory>H:\Foo\TestResults</ResultsDirectory>
    <SolutionDirectory>H:\Foo\</SolutionDirectory>
    <TargetPlatform>X64</TargetPlatform>
    <CollectSourceInformation>False</CollectSourceInformation>
  </RunConfiguration>
</RunSettings>.
[8/13/2019 10:41:56.570 AM Warning] No test is available in H:\Foo\src\bin\Release\net461\Foo.dll. Make sure that test discoverer & executors are registered and platform & framework version settings are appropriate and try again.
[8/13/2019 10:41:56.712 AM Informational] ========== Discovery finished: 0 tests found (0:00:02.0181408) ==========
[8/13/2019 10:43:20.516 AM Diagnostic] TelemetrySession: Creating the event: VS/UnitTest/TestWindow/FirstToolWindowInteraction 

This is Visual Studio Professional 2019 16.2.1 on Windows 10

[nohwnd]

VS does use vstest for discovery, but vstest does not inspect the dll to ensure that it in fact IS a test dll. Instead VS uses a set of criteria to determine if a project is a test project and sends the target dll to vstest for discovery. We then assume that there should be tests and print warning when there are none. We cannot distinguish between a dll that is not supposed to have tests, and one that has no tests because of misconfiguration.

VS scans the project for known dependencies (like depending on nunit), and I thought also for

<TestProject>false</TestProject>
<IsTestProject>false</IsTestProject>

but that does not seem to work. So this simple console app will always be scanned for tests (and fail because I don’t include any adapter).

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

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <TestProject>false</TestProject>
    <IsTestProject>false</IsTestProject>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="NUnit" Version="3.13.3" />
  </ItemGroup>

</Project>

So this is out of our control. Please fill a VS feedback for this. if there are more problems please create a new issue and reference this, rather than reviving a closed issue from 2019.

[devinvisible]

The InvalidOperationException seems to be a nuget issue when the project has multiple target frameworks and conditional assembly name:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFrameworks>net461;netcoreapp2.0</TargetFrameworks>
    <AssemblyName>Foo</AssemblyName>
  </PropertyGroup>

  <PropertyGroup Condition="'$(TargetFramework)'=='net461'">
    <AssemblyName>Foo4</AssemblyName>
  </PropertyGroup>
</Project>

The workaround I’ve used is to introduce a src\Microsoft.Common.props file that contains: <PackageId>$(MSBuildProjectName)</PackageId>

With the InvalidOperationException gone, my Tests output has changed a little; it now says that the assembly contains no NUnit 3.0 tests but it then writes out a warning.

[8/13/2019 4:12:09.395 PM Informational] ---------- Discovery started ----------
[8/13/2019 4:12:11.111 PM Informational] NUnit Adapter 3.10.0.21: Test discovery starting
[8/13/2019 4:12:11.367 PM Informational] Assembly contains no NUnit 3.0 tests: H:\Foo\src\bin\Release\net461\Foo4.dll
[8/13/2019 4:12:11.372 PM Informational] NUnit Adapter 3.10.0.21: Test discovery complete
[8/13/2019 4:12:11.382 PM Warning] No test is available in H:\Foo\src\bin\Release\net461\Foo4.dll. Make sure that test discoverer & executors are registered and platform & framework version settings are appropriate and try again.
[8/13/2019 4:12:11.509 PM Informational] ========== Discovery finished: 0 tests found (0:00:02.0412323) ==========

I want this project / assembl[y|ies] to be omitted or ignored. I expect there to be zero tests. I don’t want to see that warning message.