Example GitHub Action workflow which runs Cypress using now's deployment for the current commit. See https://mobile.twitter.com/gr2m/status/1234602143719419904

github-action-cypress-against-now-deployment.yaml

name: End-to-end tests
on: [push]
jobs:
  cypress-run:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v1
      - uses: actions/setup-node@v1
        with:
          node-version: 12
      # https://github.com/octokit/request-action/
      - uses: octokit/request-action@v2.x
        id: get_statuses
        with:
          route: GET /repos/:repository/commits/:ref/statuses
          repository: ${{ github.repository }}
          ref: ${{ github.ref }}
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
      # I assume that the most current status is set by now.
      # Only works if there are no other integrations setting commit statuses (check runs don't matter)
      # https://github.com/gr2m/get-json-paths-action/
      - id: parse_statuses
        uses: gr2m/get-json-paths-action@v1.x
        with:
          json: ${{ steps.get_statuses.outputs.data }}
          target_url: "[0].target_url"
      # replace https://zeit.co/<user>/<project>/<id>" with "<id>"
      - id: get_deployment_id
        run: echo "::set-output name=deployment_id::`echo ${{ steps.parse_statuses.outputs.target_url }} | cut -d "/" -f6`"
      - run: echo deployment id ${{ steps.get_deployment_id.outputs.deployment_id }}
      - name: Run E2E tests
        uses: cypress-io/github-action@v1
        with:
          config: watchForFileChanges=false,baseUrl=https://my-now-app-${{ steps.get_deployment_id.outputs.deployment_id }}.now.sh