ci: Add workflow to check PR description has been filled (#6965)

.github/scripts/check-pr-description.py

@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+
+"""
+Checks that a pull request description has been customized from the
+pull_request_template.md. Exits with code 1 if the description is empty
+or identical to the template (ignoring HTML comments and whitespace).
+
+Usage:
+    python check-pr-description.py --template-file TEMPLATE --pr-body-file BODY
+"""
+
+import argparse
+import re
+import sys
+from pathlib import Path
+
+
+def normalize(text: str) -> str:
+    """Strip HTML comments, trim lines, and remove blank lines."""
+    # Remove HTML comments (possibly multi-line)
+    text = re.sub(r"<!--.*?-->", "", text, flags=re.DOTALL)
+    # Strip each line and drop empties
+    lines = [line.strip() for line in text.splitlines()]
+    lines = [line for line in lines if line]
+    return "\n".join(lines)
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(
+        description="Check that a PR description differs from the template."
+    )
+    parser.add_argument(
+        "--template-file",
+        type=Path,
+        required=True,
+        help="Path to the pull request template file.",
+    )
+    parser.add_argument(
+        "--pr-body-file",
+        type=Path,
+        required=True,
+        help="Path to a file containing the PR body text.",
+    )
+    args = parser.parse_args()
+
+    template_path: Path = args.template_file
+    pr_body_path: Path = args.pr_body_file
+
+    if not template_path.is_file():
+        print(f"::error::Template file {template_path} not found")
+        return 1
+
+    if not pr_body_path.is_file():
+        print(f"::error::PR body file {pr_body_path} not found")
+        return 1
+
+    template = template_path.read_text(encoding="utf-8")
+    pr_body = pr_body_path.read_text(encoding="utf-8")
+
+    # Check if the PR body is empty or whitespace-only
+    if not pr_body.strip():
+        print(
+            "::error::PR description is empty. "
+            "Please fill in the pull request template."
+        )
+        return 1
+
+    norm_template = normalize(template)
+    norm_pr_body = normalize(pr_body)
+
+    if norm_pr_body == norm_template:
+        print(
+            "::error::PR description (ignoring HTML comments) is identical"
+            " to the template. Please fill in the details of your change."
+            f"\n\nVisible template content:\n---\n{norm_template}\n---"
+            f"\n\nVisible PR description content:\n---\n{norm_pr_body}\n---"
+        )
+        return 1
+
+    print("PR description has been customized from the template.")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())