What is the best practice to exclude certain targets when in test?

[anddrzejb]

I have several blazor projects that reference the same c# library. That library runs some gulp tasks, that take a long time (compilation of css, sass, etc). These are completely useless during tests, so I would like to skip them, when tests are executed.

Now I tried with passing a variable to the project like this from my Tests.csproj

<Project Sdk="Microsoft.NET.Sdk.Razor" InitialTargets="InformAboutTest">

  <Target Name="InformAboutTest" BeforeTargets="Build">
    <MSBuild Projects="MyProject.csproj" Properties="IsUnderTest=true;" />
  </Target>

I added this to MyProject.csproj:

  <Target Name="DebugRunGulp" BeforeTargets="DebugEnsureNodeEnv" Condition=" '$(Configuration)' == 'Debug' And Exists('$(SolutionDir)node_modules') ">
    <Message Importance="high" Text="MyProject, IsUnderTest=$(IsUnderTest)"/>
    <Exec WorkingDirectory="$(SolutionDir)" Command="npm run gulp:components" />
  </Target>

and when I run the tests I get this output:

❯ dotnet test
  You are using a preview version of .NET. See: https://aka.ms/dotnet-core-preview
  MyProject-> D:\dotnet\MyProject\bin\Debug\net6.0\MyProject.dll
  MyProject, IsUnderTest=true
  Determining projects to restore...
C:\Program Files\dotnet\sdk\6.0.100-preview.4.21255.9\Sdks\Microsoft.NET.Sdk\targets\Microsoft.PackageDependencyResolution.targets(241,5): error NETSDK1005: Assets file 'D:\dotnet\MyProject\obj\project.assets.json' doesn't have a target for 'net6'. Ensure that restore has run and that you have included 'net6' in the TargetFrameworks for your project. [D:\dotnet\MyProject\MyProject.csproj]

It seems that MyProject.csproj picks up the property, and I think I can use it, but whatever I did until now, I cannot get the project to actually successfully build. If I remove either the whole target InformAboutTest or remove it from InitialTargets, then everything builds and tests run. I also tried with adding to my target BeforeTargets="PreBuildEvent" but that does not work (MyProject is built before Tests and never gets the property). What am I missing?

[rainersigwald]

A few comments:

These are completely useless during tests, so I would like to skip them, when tests are executed.

Can you instead add incremental build support for those things so that they are skipped when not necessary, either with MSBuild-level Inputs and Outputs around the Task or with Gulp's incremental functionality? That will help for non-test build scenarios too.

I tried with passing a variable to the project like this from my Tests.csproj

<Project Sdk="Microsoft.NET.Sdk.Razor" InitialTargets="InformAboutTest">

  <Target Name="InformAboutTest" BeforeTargets="Build">
    <MSBuild Projects="MyProject.csproj" Properties="IsUnderTest=true;" />
  </Target>

Does this project also have a ProjectReference to MyProject.csproj? If so, you've created a second reference to the project, which isn't what you'd want, and you're getting the failure because you're not getting the full power of ResolveProjectReferences (specifically here it looks like your two projects have different TargetFrameworks, so the reference needs to specify that explicitly).

---

⚠ Don't do this, explanation below.

The most direct way to implement what you're doing is to tell the ProjectReference to pass your special property along:

<ProjectReference Include="..\MyProject\MyProject.csproj" AdditionalProperties="IsUnderTest=true" />

HOWEVER, that will cause a build race condition if you ever build a solution or traversal project that references both your test project and your library, because the solution->library reference will race with the "special" test->library reference.

[anddrzejb]

Thank you for your help! I will try to do the incremental build solution. However, my both projects target only net6. The message I was getting was very confusing and misleading I think...