commit-convention.yml

name: Check PR title follows commit convention

on:
    pull_request:
        types: [opened, edited, reopened]
    merge_group:

jobs:
    check-pr-title:
        name: "PR title follows commit convention"
        runs-on: ubuntu-latest
        steps:
            - name: Check PR title
              uses: actions/github-script@v9
              with:
                  script: |
                      let title;
                      if (context.eventName === 'merge_group') {
                          // The merge commit message's first line is the commit subject
                          title = context.payload.merge_group.head_commit.message.split('\n')[0];
                      } else {
                          title = context.payload.pull_request.title;
                      }

                      const types = ['feat', 'fix', 'doc', 'style', 'refactor', 'test', 'chore', 'perf'];
                      const typePattern = types.join('|');
                      const regex = new RegExp(`^(${typePattern}): .+$`);

                      const errors = [];

                      if (!regex.test(title)) {
                          errors.push(`PR title does not match the required format: \`<type>: <subject>\``);
                          errors.push(`Allowed types: ${types.join(', ')}`);
                          errors.push(`Example: \`fix: correct typo in documentation\``);
                          errors.push(`Example: \`feat: add RSS feed support\``);
                      } else {
                          // Extract subject (part after ": ")
                          const colonIndex = title.indexOf(': ');
                          const subject = title.substring(colonIndex + 2);

                          if (/^[A-Z]/.test(subject)) {
                              errors.push(`Subject must not start with a capital letter: \`${subject}\``);
                          }

                          if (subject.endsWith('.')) {
                              errors.push(`Subject must not end with a period: \`${subject}\``);
                          }
                      }

                      if (errors.length > 0) {
                          const message = [
                              'PR title does not follow the commit convention.',
                              '',
                              `Title: \`${title}\``,
                              '',
                              ...errors.map(e => `- ${e}`),
                              '',
                              'Format: `<type>: <subject>`',
                          ].join('\n');
                          core.setFailed(message);
                      } else {
                          core.info(`PR title is valid: ${title}`);
                      }