refactor(cli): move parser creation to a function

src/jcloud_docsgen/cli/cli.py

@@ -50,7 +50,15 @@ def error(message: str, exit_code: int = 1):
     print(f'{_PROGRAM_NAME}: error: {message}', file = sys.stderr)
     return exit_code
 
-def main(argv = None) -> int:
+def create_argument_parser() -> argparse.ArgumentParser:
+    '''
+    Prepares a parser to parse the command-line arguments using
+    argparse.
+
+    :return: The parser.
+    :rtype: argparse.ArgumentParser
+    '''
+
     common_parser = argparse.ArgumentParser(add_help = False)
     common_parser.add_argument(
         'project_directory',
@@ -103,6 +111,10 @@ def main(argv = None) -> int:
         help = 'indicates whether Markdown tables are allowed in the documentation. By default, Markdown tables are disabled. Warning: Markdown tables are not CommonMark.'
     )
 
+    return argument_parser
+
+def main(argv = None) -> int:
+    argument_parser = create_argument_parser()
     args = argument_parser.parse_args(argv)
 
     if args.output_dir is None: