Duplicated test runs when using LiveServerTestCase with use_reloader = True

[alisaifee]

This isn't a bug in LiveServerTestCase itself but with running the flask application using wekzeug with multiprocessing when the use_reloader option set to true. It can be reproduced with the following snippet

import unittest
import multiprocessing
import flask
import time
import random

class FlaskAppMultiProcTest(unittest.TestCase):
    def runTest(self):
        app = flask.Flask(__name__)
        proc = multiprocessing.Process(target=app.run
                , kwargs = {"use_reloader":True})
        proc.start()
        time.sleep(1)
        proc.terminate()

if __name__ == "__main__":
    unittest.main()

• Changing use_reloader to False results in single execution.
• Running the above sample will show output from the double execution.
• Replacing unittest.main() with FlaskAppMultiProcTest().runTest() will also result in double execution.
• Running the test with nosetests also results in double execution.

[alisaifee]

Looks like the reason for the multiple execution is the run_with_reloader method which when first called results in a restart_with_reloader invocation. This will make a call to subprocess.call which will run the test again and thus create a new multiprocessing.Process instance for the flask app

[alisaifee]

I have a potential solution by using tornado to server the app here in this branch https://github.com/alisaifee/flask-testing/tree/live-server

[jarus]

Sorry for my late response. I'm sorry but I don't really understand the problem. Why do you want to start a dev server with reloader inside of a test case?

[alisaifee]

Hi @jarus, I don't want to use reloader while running tests, but having the DEBUG flag results in use_reloader being set to True by default in the Flask.run method - which will probably happen more often than not when someone is writing tests

[taalexander]

I'm running into the same problem currently, is there a fix available in the current release?

[eleweek]

I started using Selenium to test my app, but it turns out that setting DEBUG = true makes tests run twice(and makes Selenium open two browsers). I'd like to see stack traces and not just "Internal Error" pages. Unfortunately, can't do this.

Is there any fix/workaround available?

[eleweek]

Looks like you can simply pass use_reloader=False when starting app. I've made a pull request: #62

[jarus]

Fixes with pull request #62.