def subnet_absent(name, virtual_network, resource_group, connection_auth=None):
    '''
    .. versionadded:: 2019.2.0

    Ensure a virtual network does not exist in the virtual network.

    :param name:
        Name of the subnet.

    :param virtual_network:
        Name of the existing virtual network containing the subnet.

    :param resource_group:
        The resource group assigned to the virtual network.

    :param connection_auth:
        A dict with subscription and authentication parameters to be used in connecting to the
        Azure Resource Manager API.
    '''
    ret = {
        'name': name,
        'result': False,
        'comment': '',
        'changes': {}
    }

    if not isinstance(connection_auth, dict):
        ret['comment'] = 'Connection information must be specified via connection_auth dictionary!'
        return ret

    snet = __salt__['azurearm_network.subnet_get'](
        name,
        virtual_network,
        resource_group,
        azurearm_log_level='info',
        **connection_auth
    )

    if 'error' in snet:
        ret['result'] = True
        ret['comment'] = 'Subnet {0} was not found.'.format(name)
        return ret

    elif __opts__['test']:
        ret['comment'] = 'Subnet {0} would be deleted.'.format(name)
        ret['result'] = None
        ret['changes'] = {
            'old': snet,
            'new': {},
        }
        return ret

    deleted = __salt__['azurearm_network.subnet_delete'](name, virtual_network, resource_group, **connection_auth)

    if deleted:
        ret['result'] = True
        ret['comment'] = 'Subnet {0} has been deleted.'.format(name)
        ret['changes'] = {
            'old': snet,
            'new': {}
        }
        return ret

    ret['comment'] = 'Failed to delete subnet {0}!'.format(name)
    return ret