如果测试先决条件失败，完全退出 locust 进程的最干净的方法是什么？

Question

I have an 'on_test_start' hook that tests for the existence of some environmental variables before the test starts:

@events.test_start.add_listener
def on_test_start(**_kwargs):
    env_vars_present = check_vars.check_existence_of_env_vars(["VAR1", "VAR2"])
    if not env_vars_present:
        sys.exit()

This works, but I don't like using sys.exit() which is a rather dirty way to quit a process. Is there a better alternative? I've tried raising an exception, but this doesn't stop the runners. I've also tried environment.runner.quit() . This quits the runners, but locust process continues until run-time limit is reached. What's the cleanest way to exit the process if some prerequisite checks fail? Thanks!

Answer 1

You have the right idea with environment.runner.quit() you just need to have that happen on the master, not the workers. You need the workers to communicate the failure to the master and then the master can can quit, which will stop the master and all the workers.

You could either use other Event Hooks like request with a custom Name you could check a failure for, report_to_master to add in some extra data to the report payload sent to the master that you could check for its existence and quit on. Both of those you'd use worker_report on the master to trigger your check and quit. Doing it this way could help you get these steps in any test output data so you could clearly see what the problem was without doing much custom reporting work.

Along the same lines but maybe slightly cleaner and more direct would be to use the communication between nodes to have the workers send a message directly to the master and have the master quit when that message was received. Code would look something like this:

@events.init.add_listener
def quit_env_failure_message(environment, **_kwargs):
    global ENV
    ENV
    if isinstance(environment.runner, MasterRunner):
        environment.runner.register_message('env_failure', quit_on_env_failure)


def quit_on_env_failure(msg, **kwargs):
    ENV.runner.quit()


@events.test_start.add_listener
def on_test_start(**_kwargs):
    env_vars_present = check_vars.check_existence_of_env_vars(["VAR1", "VAR2"])
    if not env_vars_present:
        environment.runner.send_message('env_failure')

Doing it this way, you may need to do extra work to get whatever kind of tests result reporting you'd want. That would most likely go in quit_on_env_failure() .