click.testing.CliRunner and handling SIGINT/SIGTERM signals

Question

I want to add few tests on how my cli app handles different signals (SIGTERM, etc). And I am using native testing solution click.testing.CliRunner alongside of pytest.

Test looks pretty standard and simple

def test_breaking_process(server, runner):

    address = server.router({'^/$': Page("").exists().slow()})

    runner = CliRunner(mix_stderr=True)
    args = [address, '--no-colors', '--no-progress']
    result = runner.invoke(main, args)
    assert result.exit_code == 0

And here I am stuck, how could I send SIGTERM to process in runner.invoke? I see no problem to do it if I use e2e tests (calling executable and not CLIrunner), but I would like to try to implement this (at least able to send os.kill)

is there a way to do it?

A signal is asynchronous. So you need someway to trigger it from a different thread. https://stackoverflow.com/questions/49474435/unit-test-python-signal-handler. — Stephen Rauch, Dec 12 '19 at 02:05

score 2 · Answer 1 · answered Dec 12 '19 at 11:42

So, if you want to test your click powered application for handling different signals, you can do next procedure.

def test_breaking_process(server, runner):

    from multiprocessing import Queue, Process
    from threading import Timer
    from time import sleep
    from os import kill, getpid
    from signal import SIGINT

    url = server.router({'^/$': Page("").slow().exists()})
    args = [url, '--no-colors', '--no-progress']

    q = Queue()

    # Running out app in SubProcess and after a while using signal sending 
    # SIGINT, results passed back via channel/queue  
    def background():
        Timer(0.2, lambda: kill(getpid(), SIGINT)).start()
        result = runner.invoke(main, args)
        q.put(('exit_code', result.exit_code))
        q.put(('output', result.output))

    p = Process(target=background)
    p.start()

    results = {}

    while p.is_alive():
        sleep(0.1)
    else:
        while not q.empty():
            key, value = q.get()
            results[key] = value

    assert results['exit_code'] == 0
    assert "Results can be inconsistent, as execution was terminated" in results['output']

click.testing.CliRunner and handling SIGINT/SIGTERM signals

1 Answers1