Add test command in PR comment (#9)

.github/workflows/pr-comment.yml

@@ -0,0 +1,39 @@
+name: PR comment test
+
+on:
+  issue_comment:
+    types: [created]
+
+env:
+  PRIVATE_KEY: ${{ secrets.PRIVATE_KEY }}
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  run-test:
+    name: run test
+    runs-on: ubuntu-latest
+    if:
+      github.event.issue.pull_request
+      && github.event.issue.state == 'open'
+      && contains(github.event.comment.body, '!test')
+      && (github.event.comment.author_association == 'MEMBER' || github.event.comment.author_association == 'OWNER')
+  steps:
+    - uses: xt0rted/pull-request-comment-branch@v2
+      id: comment-branch
+    - uses: actions/checkout@v4
+    - name: Checkout PR branch
+      run: gh pr checkout ${{ github.event.issue.number }}
+      env:
+        # TODO: Remove if not needed
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    - name: Check private key exists
+      # Potential alternative: https://github.com/myrotvorets/set-commit-status-action
+      uses: actions/github-script@v6
+      with:
+        script: |
+          if ("$PRIVATE_KEY" == "") {
+            core.setFailed('Failed to access PRIVATE_KEY secret')
+          }