Test workflows for actions can be automated in the action repo so that whenever a new PR is raised to master or releases/* branches these workflows evaluate on the branch from which PR is raised.

This process of automated testing enables one to run tests on PRs from a branch in a repo and also PRs from a forked repo. Inorder to ensure the safety of secrets which are used by the pr-check workflows and to prevent pwn requests, the pr-check workflow and secrets should be a part of a github environment and set appropriate approval policy for triggering this workflow on a new PR.

So whenever a new PR occurs (especially from a forked repo) , the PR is manually reviewed for security vulneribilities and then approved after which the pr-check workflow is triggered for the new PR. Approvers should manually review for these before approving the check to run on PR.

1. Create a pr-check.yml workflow in .github/workflows of the action repo. Setup Automation test environment in the action and enable appropriate approval policy which includes adding reviewers list to approve the PR to run the pr-check. Visit this to know more about environments.
2. Put the triggering condition for this workflow as on: pull_request_target if forked repo PR checks need to be checked automatically otherwise on: pull_request should do. Visit pull_request_target for more details.
3. Steps include:
   1. Checkout the repo.
   2. Setup the Node.js for github action.
   3. Install the node_modules using npm install as the PRs raised to master branch will not have node_modules without which the workflow fails.
   4. Build the action using npm run build( Since some action repos don’t have the updated lib/.js files as they recommend to exempt lib/.js in PRs. This step ensures the action to have updated lib files).
   5. Here we are targeting to run a sample test for the action.For multiple scenarios, one can mention different scenarios in the same file and have multiple steps in the WF file calling the necessary actions for the required setup(For example if a .Net app needs to be deployed ,make sure you set up .Net using actions/setup-dotnet@v1 and resolve those dependencies here).
   6. Run the action with uses: ./ which will pick the current branch of the repo to execute the workflow. Specify the input parameters which are required by the action in the with: parameters.

name: pr-check

on:
  pull_request_target:
    branches:
      - master
      - 'releases/*'

jobs:
    deploy:
      environment: Automation test
      runs-on: windows-latest
      steps:
      - name: Checkout from PR branch  
        uses: actions/checkout@v2
        with: 
          repository: ${{ github.event.pull_request.head.repo.full_name }}
          ref: ${{ github.event.pull_request.head.ref }}
        
        #Using 12.x version as an example
      - name: Set Node.js 12.x for GitHub Action
        uses: actions/setup-node@v1
        with:
          node-version: 12.x

      - name: installing node_modules
        run: npm install 
       
      - name: Build GitHub Action
        run: npm run build
          
      # include any workflow/action specific dependencies
      
      - uses: ./                  #picks the current action PR code.
        with:
          #input parameters of the action.