Writing automated tests is an essential part of writing reliable software. Automated tests are scripts that check the functionality of your program and verify that it is working correctly. PsyNet provides easy-to-use tools for writing tests for your own experiment implementations; we recommend you use them whenever designing your own experiment.
All the demos in the PsyNet package are set up already with simple
automated tests. For this tutorial, we recommend you open up the
static_audio demo to see how this is done.
The convention is for PsyNet experiment directories to contain a
test.py file. This
test.py file does not typically
contain any experiment-specific code; every demo has the same file.
This file uses the
pytest package to invoke a generic testing method
defined on the Experiment class.
You can run this test by navigating to the experiment directory
and entering the following in your command line:
psynet test local
or, if using PsyNet within Docker:
bash docker/psynet test local
This command takes a few moments to start as it has to spin up a
PsyNet local server. Once the server is ready,
Experiment.test_experiment method is called.
This creates one or more ‘bots’, or virtual participants;
these bots progress through the experiment one page at a time.
Once the bots all reach the end of the experiment, and all relevant
checks have passed, the test script concludes.
If an error occurs, then a traceback is printed, giving you a
chance to debug it.
class Experiment(...): ... test_n_bots = 1 def test_experiment(self): os.environ["PASSTHROUGH_ERRORS"] = "True" os.environ["DEPLOYMENT_PACKAGE"] = "True" bots = self.test_create_bots() self.test_run_bots(bots) self.test_check_bots(bots)
The default behavior of the
test_experiment is to create
one bot and run it through the entire experiment, one page at a time.
Unless you tell it otherwise, the bot will generate a random plausible
response for most page types. For example, if the page asks for
a multiple-choice response, the bot will typically choose its response
at random. This behavior can be customized by setting the
argument when a page is created, either to a fixed value that the
bot always returns (e.g.
True), or to a function that is invoked
each time the bot reaches that page.
The ‘static audio’ demo shows an example where audio is recorded
from a participant. In this case we set
bot_response_media="example-bier.wav" within the
AudioRecordControl; this tells the test to use the
file as the bot’s response in all cases.
By default all the test does is check that the bot can get to the
end of the experiment without errors. However it’s often sensible
to implement some additional checks to make sure that the state of
the experiment is as you expect it. One way of doing this
is to override the
This method is run when the bot completes the experiment.
At this point you can run some custom code to check that the
bot has the right status. In the ‘static audio’ demo,
is used to verify that the bot has taken the right number of trials.
def test_check_bot(self, bot: Bot, **kwargs): assert len(bot.alive_trials) == len(nodes)
These customizations are often enough for simple use cases. However, it’s possible to provide arbitrarily complex logic for these tests. For an example of a complex test, have a look at the “rock, paper, scissors” demo, which has multiple bots take the experiment at the same time, and coordinates how they step through the experiment together.
class Experiment(...): ... test_n_bots = 2 def test_run_bots(self, bots: List[Bot]): from psynet.page import WaitPage advance_past_wait_pages(bots) page = bots.get_current_page() assert page.label == "choose_action" bots.take_page(page, response="rock") page = bots.get_current_page() assert isinstance(page, WaitPage) page = bots.get_current_page() assert page.label == "choose_action" bots.take_page(page, response="paper") advance_past_wait_pages(bots) pages = [bot.get_current_page() for bot in bots] assert pages.content == "You chose rock, your partner chose paper. You lost." assert pages.content == "You chose paper, your partner chose rock. You won!" bots.take_page() bots.take_page() advance_past_wait_pages(bots) bots.take_page(page, response="scissors") bots.take_page(page, response="paper") advance_past_wait_pages(bots) pages = [bot.get_current_page() for bot in bots] assert ( pages.content == "You chose scissors, your partner chose paper. You won!" ) assert ( pages.content == "You chose paper, your partner chose scissors. You lost." ) bots.take_page() bots.take_page() advance_past_wait_pages(bots) bots.take_page(page, response="scissors") bots.take_page(page, response="scissors") advance_past_wait_pages(bots) pages = [bot.get_current_page() for bot in bots] assert ( pages.content == "You chose scissors, your partner chose scissors. You drew." ) assert ( pages.content == "You chose scissors, your partner chose scissors. You drew." ) bots.take_page() bots.take_page() advance_past_wait_pages(bots) pages = [bot.get_current_page() for bot in bots] for page in pages: assert isinstance(page, SuccessfulEndPage)
By default the PsyNet experiment test just sends one bot through the entire experiment. It is possible however to send more bots through the same experiment, and to tell PsyNet to run those bots through the experiment in parallel, to give a better simulation of the load incurred by a real experiment. To change the default behavior for a given experiment, you can set the relevant attributes on the experiment class, like this:
class Experiment(...): ... test_n_bots = 5 test_modes = ["parallel"]
Alternatively, you can set these options when you call
psynet test, for example by writing:
psynet test --n-bots 5 --parallel
Testing on remote servers#
Sometimes it’s useful to test an experiment on remote server to get a better idea of how the server will cope with large numbers of participants. First you need to launch a debug experiment to the server:
psynet debug ssh --app my-experiment
Then you invoke
psynet test, similar to before but with
ssh instead of
psynet test ssh --app my-experiment --n-bots 5 --parallel
The tests described above focus on testing the back-end logic of your
PsyNet experiment. They catch errors to do with the instantiation of pages,
the running of code blocks, the growing of networks, and so on.
They do not catch logic to do with the front-end display of your
experiment. Writing such tests is more complicated, and we haven’t
provided a tutorial for this yet; however, if you are interested in writing
your own such tests, please have a look at corresponding tests in the
PsyNet source code, for example
The front-end testing patterns mentioned above (e.g.
have certain restrictions, most notably that they do not test concurrency.
To bypass these restrictions, some PsyNet users have found it useful to write custom Selenium tests.
Here is a minimal example of a custom Selenium test (provided without warranty) that could be extended
to test multiple concurrent users, which you would run by executing
python3 bot.py --app test-app.
Thanks Pol van Rijn for this example!
import argparse parser = argparse.ArgumentParser() parser.add_argument("--app", help="Enter app name here", required=True) parser.add_argument("--headless", default=1, type=int, help="Headless") args = parser.parse_args() from selenium import webdriver from selenium.webdriver.common.action_chains import ActionChains import random import time import os import psycopg2 chrome_options = webdriver.ChromeOptions() chrome_options.add_argument('--disable-extensions') if args.headless == 1: chrome_options.add_argument('--headless') chrome_options.add_argument("--disable-plugins-discovery") driver = webdriver.Chrome('/usr/local/bin/chromedriver', chrome_options=chrome_options) driver.delete_all_cookies() driver.set_window_size(800,800) driver.set_window_position(0,0) APP_NAME = args.app credentials = os.popen('heroku pg:credentials:url -a dlgr-%s' % APP_NAME).read().split('\n').lstrip()[1:-1].split(' ') creds = dict([c.split('=') for c in credentials]) # Remove fingerprint_hash conn = psycopg2.connect(dbname=creds['dbname'], user=creds['user'], password=creds['password'], host=creds['host']) with conn: with conn.cursor() as cur: cur.execute('select id,fingerprint_hash from participant') for id, fingerprint_hash in cur.fetchall(): cur.execute('UPDATE "public"."participant" SET "fingerprint_hash"=NULL WHERE "id"=%d' % id) conn.close() hash = random.getrandbits(16) recruitment = 'https://dlgr-%s.herokuapp.com/ad?recruiter=hotair&assignmentId=%s&hitId=%s&workerId=%s&mode=debug' % (APP_NAME, hash, hash, hash) driver.get(recruitment) # Begin experiment driver.find_element_by_xpath('//*[@id="begin-button"]').click() # Move to popup window_after = driver.window_handles driver.switch_to_window(window_after) # Accept consent 1 and 2 driver.execute_script("next_consent_page();") driver.execute_script("window.location='/start?';") time.sleep(10) while True: try: next_btn = driver.find_element_by_xpath('//*[@id="next_button"]') status = next_btn.get_attribute('disabled') if status is None: next_btn.click() else: slider = driver.find_element_by_id("sliderpage_slider") move = ActionChains(driver) offset = random.randint(0, 500) if random.randint(0, 1) == 0: offset = offset * -1 move.click_and_hold(slider).move_by_offset(offset, 0).release().perform() time.sleep(2) except: print('Finished') driver.close() break