upload-release/.github/workflows/ci.yml

name: "CI"
on: [pull_request, push]

jobs:
  build: # make sure build/ci work properly
    name: CI on ${{ matrix.os }}
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
    steps:
      - uses: actions/checkout@v2
      - run: |
          npm install
          npm run all          

  # make sure the action works on a clean machine without building
  test_1:
    name: E2E test on draft release
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
    steps:
      - id: get_tag
        run: echo "::set-output name=new_tag::ci-test-1-${{ matrix.os }}-${{ github.run_id }}"
      - uses: actions/checkout@v2
      - id: create_release
        name: create temporary release for testing
        uses: actions/create-release@v1
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          tag_name: ${{ steps.get_tag.outputs.new_tag }}
          release_name: Release ${{ steps.get_tag.outputs.new_tag }}
          body: |
            Changes in this Release
            - First Change
            - Second Change            
          draft: true
          prerelease: false
      - name: Make test pre-release
        uses: ./
        with:
          repo_token: ${{ secrets.GITHUB_TOKEN }}
          tag: ${{ steps.get_tag.outputs.new_tag }}
          file: README.md
          asset_name: TEST.md
          overwrite: true
      - name: Check that the uploaded asset is readable
        uses: actions/github-script@v2
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const assert = require('assert').strict;
            const release = await github.repos.getRelease({
              ...context.repo,
              release_id: "${{ steps.create_release.outputs.id }}",
            })
            assert.deepStrictEqual(release.data.assets[0].name, "TEST.md")
            // For a draft release, the `browser_download_url` cannot be used
            // since the release hasn't been published yet.            
      - name: Clean up
        if: ${{ always() }}
        uses: actions/github-script@v2
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            await github.repos.deleteRelease({
              ...context.repo,
              release_id: ${{ steps.create_release.outputs.id }},
            })            

  test_2:
    name: E2E test on published release
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
    steps:
      - id: get_tag
        run: echo "::set-output name=new_tag::ci-test-2-${{ matrix.os }}-${{ github.run_id }}"
      - uses: actions/checkout@v2
      - id: create_release
        name: create temporary release for testing
        uses: actions/create-release@v1
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          tag_name: ${{ steps.get_tag.outputs.new_tag }}
          release_name: Release ${{ steps.get_tag.outputs.new_tag }}
          body: |
            Changes in this Release
            - First Change
            - Second Change            
          draft: false
          prerelease: false
      - name: Make test pre-release
        uses: ./
        with:
          repo_token: ${{ secrets.GITHUB_TOKEN }}
          tag: ${{ steps.get_tag.outputs.new_tag }}
          file: README.md
          asset_name: TEST.md
          overwrite: true
      - name: Check that the uploaded asset is readable
        uses: actions/github-script@v2
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const fs = require('fs')
            const child_process = require('child_process');
            const assert = require('assert').strict;

            const expected = fs.readFileSync("README.md")
            const release = await github.repos.getReleaseByTag({
              ...context.repo,
              tag: "${{ steps.get_tag.outputs.new_tag }}",
            })
            assert.deepStrictEqual(release.data.assets[0].name, "TEST.md")
            const actual = child_process.execSync(`curl -Ls ${release.data.assets[0].browser_download_url}`)
            assert.deepStrictEqual(expected, actual)            
      - name: Clean up
        if: ${{ always() }}
        uses: actions/github-script@v2
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            await github.repos.deleteRelease({
              ...context.repo,
              release_id: ${{ steps.create_release.outputs.id }},
            })
            await github.git.deleteRef({
              ...context.repo,
              ref: "tags/${{ steps.get_tag.outputs.new_tag }}",
            })