name: Is Pull Request

# This job succeeds for every pull request. Then, in settings, we protect trunk
# such that every commit to trunk must have this job succeed. This effectively
# makes it such that no one can push directly to `trunk`, since only PRs can
# include this check.

# We need this because you can only forbid pushing to `trunk` based on branch
# protection rules. We only utilize the "Require status checks to pass before
# merging" branch protection rule. If we wanted every other normal "check" to NOT
# be required, then there would be no "required check" which prevents pushing
# to trunk. As a result, we have this little fake "check" which will always show
# up on PRs to prevent direct commits to trunk.

on:
  pull_request:
    types: [ opened, synchronize ]

jobs:
  is-pull-request:
    name: 'Protect Trunk Branch'
    runs-on: ubuntu-latest
    steps:
    - name: Tells you that it's a pull request
      run: 'echo "This is a pull request 👍."'