chore: import upstream snapshot with attribution

tests/github/test_pr_autoformat.py

@@ -0,0 +1,44 @@
+from __future__ import annotations
+
+import importlib.util
+import sys
+from pathlib import Path
+
+_SCRIPT = Path(__file__).parents[2] / ".github" / "scripts" / "pr-template" / "format_body.py"
+sys.path.insert(0, str(_SCRIPT.parent))
+_SPEC = importlib.util.spec_from_file_location("pr_autoformat", _SCRIPT)
+assert _SPEC is not None and _SPEC.loader is not None
+pr_autoformat = importlib.util.module_from_spec(_SPEC)
+_SPEC.loader.exec_module(pr_autoformat)
+
+
+def test_wraps_existing_description_in_summary_without_deleting_it() -> None:
+    formatted = pr_autoformat.format_body("Fix the important thing.")
+
+    assert formatted.startswith("## Summary\n\nFix the important thing.")
+    assert "## Type of change" in formatted
+    assert "- [ ] Bug fix" in formatted
+    assert "## Test coverage" in formatted
+    assert "- [ ] Unit tests added / updated" in formatted
+
+
+def test_preserves_existing_sections_and_adds_missing_optional_context() -> None:
+    original = "## Summary\n\nExisting summary.\n\n## Type of change\n\n- [x] Feature\n"
+    formatted = pr_autoformat.format_body(original)
+
+    assert "Existing summary." in formatted
+    assert "- [x] Feature" in formatted
+    assert formatted.count("## Summary") == 1
+    assert formatted.count("## Type of change") == 1
+    assert "## ELI5" in formatted
+    assert "## Diagram" in formatted
+    assert "## Test Plan" in formatted
+    assert "## Coverage notes" in formatted
+    assert "## Changelog" in formatted
+
+
+def test_scaffolds_changelog_section_with_delete_placeholder() -> None:
+    formatted = pr_autoformat.format_body("Fix the important thing.")
+    assert "## Changelog" in formatted
+    # The scaffolded section defaults to the delete-if-not-noteworthy placeholder.
+    assert formatted.rstrip().endswith("else delete this section>")