listDartSources function
Every .dart file under root, recursively, in path order.
Implementation
List<String> listDartSources(String root) {
final dir = Directory(root);
if (!dir.existsSync()) return const [];
return dir
.listSync(recursive: true)
.whereType<File>()
.map((f) => f.path)
.where((path) => p.extension(path) == '.dart')
.toList()
..sort();
}