changelog.yml

name: Pull request changelog

on:
  pull_request_target:
    types: [labeled, unlabeled, synchronize]

jobs:
  check-changelog:
    name: 'check changelog'
    runs-on: ubuntu-latest

    steps:
    - name: Check if version label is present
      id: labels
      uses: actions/github-script@v2
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }}
        script: |
          const versionLabels = [
            'Action: no bump',
            'Action: beta bump',
            'Action: patch bump',
            'Action: minor bump',
            'Action: major bump',
          ];

          const { data: pullLabels } = await github.issues.listLabelsOnIssue({
            owner: context.repo.owner,
            repo: context.repo.repo,
            issue_number: context.payload.pull_request.number,
            per_page: 100,
          });

          const labels = pullLabels.map(label => label.name);

          const versionLabelsPresent = labels
            .filter(name => versionLabels.includes(name));

          console.log(`::debug ::${versionLabelsPresent.length} matching labels`);

          if (versionLabelsPresent.length !== 1) {
            throw new Error('Should have one and only one version bump label');
          }

          const versionLabel = versionLabelsPresent[0];
          console.log(`::set-output name=versionLabel::${versionLabel}`)

          if (versionLabel === 'Action: no bump') {
            return;
          }

    - name: Fail if no changelog change when needed
      if: |
        steps.labels.outputs.versionLabel != 'Action: no bump'
        && steps.labels.outputs.versionLabel != 'Action: beta bump'
      uses: actions/github-script@v2
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }}
        script: |
          const { data: files } = await github.pulls.listFiles({
            owner: context.repo.owner,
            repo: context.repo.repo,
            pull_number: context.payload.pull_request.number,
            per_page: 100,
          });

          const changelogFile = 'CHANGELOG.md';

          const fileNotDeletedNames = files
            .filter(file => file.status === 'added' || file.status === 'modified')
            .map(file => file.filename);

          if (!fileNotDeletedNames.includes(changelogFile)) {
            throw new Error('CHANGELOG.md Unreleased section shoud have line additions when PR is not a no-release')
          }