Unable to test using older target frameworks following setup

Description

Running dotnet test following setup does not allow testing against specific older frameworks. This used to be possible.

Details

Given the following workflow.

name: .NET Core

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  build:
    strategy:
        matrix:
            options:
                - os: windows-latest
                  framework: netcoreapp3.1
                - os: windows-latest
                  framework: netcoreapp2.1

    runs-on: ${{matrix.options.os}}

    steps:
    - uses: actions/checkout@v2

    - name: Setup .NET Core
      uses: actions/setup-dotnet@v1
      with:
        dotnet-version: 3.1.x

    - name: Install dependencies
      run: dotnet restore

    - name: Build
      run: dotnet build --configuration Release --no-restore -f ${{matrix.options.framework}}

    - name: Test
      run: dotnet test --no-restore --verbosity normal -f ${{matrix.options.framework}}

It used to be possible to specify an older target framework. For example :

dotnet test --no-restore --verbosity normal -f netcoreapp2.1

Now the following exception is returned instead.

Testhost process exited with error: It was not possible to find any compatible framework version
The framework 'Microsoft.NETCore.App', version '2.1.0' was not found.
  - The following frameworks were found:
      3.1.9 at [C:\Users\runneradmin\AppData\Local\Microsoft\dotnet\shared\Microsoft.NETCore.App]
You can resolve the problem by installing the specified framework and/or SDK.
The specified framework can be found at:
  - https://aka.ms/dotnet-core-applaunch?framework=Microsoft.NETCore.App&framework_version=2.1.0&arch=x64&rid=win10-x64
. Please check the diagnostic logs for more information.

Build works fine and removing this action allows the test command to run as expected.

I’ve created a repository that demonstrates the issue. https://github.com/JimBobSquarePants/SetupDotNetActionFailRepro

[vsafonkin]

Most likely a second version of setup task which will be released which will install required dotnet to the directory with pre-installed versions.

[visschersm]

I just want to say thanks for this solution. Been trying to get my tests back work the entire day and this seems to be the solution.

Still think it is a bit strange that you can build/run/test from the CLI using the latest available SDK to build/test every version below. But it does not work the same way within the github action.