Sample .NET Core GitHub actions workflow, with published markdown tests results using LiquidTestReports.Markdown - https://www.nuget.org/packages/LiquidTestReports.Markdown

GitHub Action Test Publish

name: .NET Core Build with Tests

on:
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]

jobs:
  build:
    runs-on: ubuntu-latest
    env:
      config: 'Release'
      
    steps:
    - uses: actions/checkout@v2
    - name: Setup .NET Core
      uses: actions/setup-dotnet@v1
      with:
        dotnet-version: 3.1.101    
      
      # restore dependencies  
    - name: Install dependencies
      run: dotnet restore
      
      # build project
    - name: Build
      run: dotnet build --configuration $config --no-restore
      
    - name: set pr build number (if pr)
      id: PRNUMBER
      if: ${{ github.event_name == 'pull_request' }}
      uses: kkak10/pr-number-action@v1.3
      
      # set report file and title 
    - name: Set Test Title
      run: | 
            if ${{ github.event_name == 'pull_request' }}
            then
              echo "title=Test Run for PR #${{steps.PRNUMBER.outputs.pr}} (${{github.run_number}})" >> $GITHUB_ENV
              echo "file_name=TestReport.${{steps.PRNUMBER.outputs.pr}}.${{github.run_number}}.md" >> $GITHUB_ENV              
            else
              echo "title=Test Run ${{github.run_number}}" >> $GITHUB_ENV
              echo "file_name=TestReport.${{github.run_number}}.md" >> $GITHUB_ENV
            fi
      
      # run tests with built project
    - name: Test PR      
      run: dotnet test --no-restore --no-build --configuration $config --logger:"liquid.md;LogFileName=${{github.workspace}}/${{env.file_name}};Title=${{env.title}};"
      
      # upload report as build artifact
    - name: Upload a Build Artifact
      uses: actions/upload-artifact@v2
      if: ${{always()}}
      with:
        name: 'Test Run'
        path: ${{github.workspace}}/${{env.file_name}}
      
      # add report as PR comment (if PR)
    - name: comment PR
      uses: machine-learning-apps/pr-comment@master
      if: ${{ github.event_name == 'pull_request' }}
      env:
        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      with:
        path: ${{env.file_name}}

Sample of PR Comment output:

@kurtmkurtm This is not working anymore since last month https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/

Here is the fix

diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index 63b48db..840deec 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -37,11 +37,11 @@ jobs:
         run: |
           if ${{ github.event_name == 'pull_request' }}
           then
-            echo "::set-env name=title::Test Run for PR #${{steps.PRNUMBER.outputs.pr}} (${{github.run_number}})"
-            echo "::set-env name=file_name::TestReport.${{steps.PRNUMBER.outputs.pr}}.${{github.run_number}}.md"
+            echo "title=Test Run for PR #${{steps.PRNUMBER.outputs.pr}} (${{github.run_number}})" >> $GITHUB_ENV
+            echo "file_name=TestReport.${{steps.PRNUMBER.outputs.pr}}.${{github.run_number}}.md" >> $GITHUB_ENV
           else
-            echo "::set-env name=title::Test Run ${{github.run_number}}"
-            echo "::set-env name=file_name::TestReport.${{github.run_number}}.md"
+            echo "title=Test Run ${{github.run_number}}" >> $GITHUB_ENV
+            echo "file_name=TestReport.${{github.run_number}}.md" >> $GITHUB_ENV
           fi

         # run tests with built project

Thanks @segadora, I've updated the gist with your suggested fix.