It is impossible to use Matrix Testing with different frameworks

I have to test multitargeted library with frameworks matrix, but it is impossible to map target framework to dotnet-version.

For example, I have workflow:

strategy:
  fail-fast: false
  matrix:
    framework: [net48, netcoreapp2.1, netcoreapp3.1, net5.0, net6.0]

steps:
- name: Install .NET
  uses: actions/setup-dotnet@main
  with:
    dotnet-version: ???
  
- name: Test
  run: dotnet test <my project> --framework ${{ matrix.framework }}

and want to install only dotnet 2.1.x for netcoreapp2.1 target, dotnet 5.0.x for net5.0 target and so on.

Also, it seems that installing only dotnet 6.0.x is not enough to run tests under net5.0.

[KungA]

Ok, it is not too important to me, and I’ll use huge syntax with conditionals.

[kzrnm]

Since you are targeting 5 frameworks, I think it is natural that your tests take 5x times longer.