JS tests depend on Cloudflare CDN for every run

[Hugo Herter]

Running the Javascript tests requires an internet connection to ​https://cdnjs.cloudflare.com .

This makes the tests dependent on an extra third party, provides that third party with the IP address of developers and test runners, and prevents developers from running the tests without a connection to Cloudflare.

The relevant line is in js_tests/tests.html:

<script src='​https://cdnjs.cloudflare.com/ajax/libs/ol3/4.6.5/ol.js'></script>

How to reproduce

1. Install the dependencies using npm

git clone ​https://github.com/django/django.git
cd django/
npm install

2. Serve the page via a web server and open in in a browser

python3 -m http.server --bind 127.0.0.1

Open ​http://localhost:8000 with the network inspector open.

[Mariusz Felisiak]

This was intentionally changed in b1d6b0a7b121eec860b518b4903d7c8c74f7773b (see also #26098). I'm not sure what kind of alternative you're proposing, we definitely don't want to copy OpenLayers.js to the Django repository. It's also ​documented that cdnjs.cloudflare.com is used for OpenLayersWidget.

[Claude Paroz]

I'm not very happy, too, to have this connection on test runs, but as Mariusz said, we do not have satisfying alternatives yet. I hope that in the future, we might have some way of local caching of such external dependencies.