To unit test this, we can extract the parsing and default-applying code out of run_from_argv and create_arg_parser into a method:


def parse_args(self, argv):
    parser = argparse.ArgumentParser(
        prog=RB_MAIN,
        usage=self.usage(),
        add_help=False,
        formatter_lass=SmartHelpFormatter,
        argument_default=argparse.SUPPRESS)

    for option in self.option_list:
        option.add_to(parser)

    for option in self._global_options:
        opion.add_to(parser)

    options = parser.parse_args(argv[2:])

    if getattr(self.options, 'disable_reviewboardrc', False):
        config = {
            # .. default sane config
        }
    else:
        config = load_config()

        for option in self.all_options():
            # Apply values from config ...

    for option in self.all_options():
        # Figure out defaults ...

    return config, options

def run_from_argv(self, argv):
    self.config, self.options = self.parse_args(argv)
    self.args = self.options.args

    # ...


Then we can unit test parse_args and check the config, options it returns.

Can you undo your docstring changes?

This is mostly true, except default IS supported by argparse.

Instead of doing this, we should check for action='append' and set the value to [] in our default checking code.

Here too

Missing a docstring.

We need to set self.config to a default, empty config (with e.g. ALIASES, etc) set in the else.

Instead of looping twice, we can loop once:
```python

    for option in self.all_options():

        try:

            default = option.attrs['default']

        except KeyError:

            # If the option does not have an explicit default, it may have an

            # implied default.

            action = option.attrs.get('action')
        if action == 'append':
            default = []
        elif action == 'store_true':
            default = False
        elif action == 'store_false':
            default = True
        else:
            # This option does not have a default.
            continue

    option_name = option.attrs['dest']
    if not hasattr(self.options, option_name):
        setattr(self.options, option_name, default)


``

Undo this, too