def METHOD_NAME(self, update_resource_tags):
    """Verifies we can add a new tag to a VM from values on the VM
    when values do not exist with default-value
    """
    action = self._get_action(
        {
            'tag': {
                'type': 'resource',
                'key': 'doesnotexist',
                'default-value': 'default_tag'
            },
            'value': {
                'type': 'resource',
                'key': 'doesnotexist',
                'default-value': 'default_value'
            }
        })
    resource = tools.get_resource(self.existing_tags)
    action.process([resource])
    tags = tools.get_tags_parameter(update_resource_tags)
    expected_tags = self.existing_tags.copy()
    expected_tags.update({'default_tag': 'default_value'})
    self.assertEqual(tags, expected_tags)