some example code

deploy.py

@fabric.api.serial
def stop(app_name):
    fabric.api.run('service {} stop'.format(app_name))
    
@mock.patch('fabric.api.run')
def test_stop_runs_nice_command(run_mock):
    stop("awesome-app")
    run_mock.verify_called_with("service awesome-app stop")

# More low-level commands like that, with similar test cases, then higher level code

def restart(application_config):
    app_name = application_config.name
    hosts = application_config.hosts
    for host in hosts:
      fabric.api.execute(stop, app_name, hosts=hosts)
      fabric.api.execute(start, app_name, hosts=hosts)
      
@mock.patch('fabric.api.execute')
def test_that_app_is_stopped_only_on_one_server_at_a_time(execute_mock):
    application_config = ApplicationConfig("awesome-app", ["server-1", "server-2"])
    restart(application_config)
    assert execute_mock.has_calls([
        mock.call(stop, "awesome-app", hosts=["server-1"]),
        mock.call(start, "awesome-app", hosts=["server-2"]),
        mock.call(stop, "awesome-app", hosts=["server-1"]),
        mock.call(start, "awesome-app", hosts=["server-2"])
    ])