XHR PUT/DELETE Requests on Electron Browser fail with Http Failure Response

[andrewryan1906]

Current behavior:

I have a set of tests that run against an Angular 7 application with no problem on the Chrome browser. This same set, however, fails when running on the Electron 59 browser. It's consistent and reproducible for me; upon further inspection, I noticed that all of the tests that fail do so when making PUT or DELETE requests to my back end REST API; POST requests function properly, and the tests that use them pass. So my "create" tests pass, whereas my "edit" and "delete" tests fail. The error screen:

You can see the error Http failure response for (unknown url): 0 Unknown Error

I turned on debugging and was unable to see anything in the XHDR outputs in the logs, and thus could not reproduce the problem.

Desired behavior:

Tests should run properly both in Electron 59 and in Chrome.

Steps to reproduce: (app code and test code)

If you'd like, I can add you to my application repo so you can run the failing test yourself. As I said, the challenge is that it only fails when running Electron; it behaves properly in Chrome. Reply with your username and I will give you access to the repo.

Versions

Cypress 3.1.3, Windows 10
Using API Gateway/Lambda for the backend, and CORS is properly configured.

[andrewryan1906]

A bit more info.. I ran the Electron browser headed and was able to reproduce. This time, I got access to the developer console, and the error I'm seeing is:

XMLHttpRequest cannot load https://api.rolodex.us-east-2-992899858538.mydomain.com/v1/tests/customActivityTypes/CYPRESS_ACTIVITY_TYPE. Method PUT is not allowed by Access-Control-Allow-Methods in preflight response.

This doesn't make sense, since I have CORS enabled and all of my API gateways, everything works in Chrome, and it's been working for ages. I double checked and the pre-flight OPTIONS request is indeed returning properly... screenshot:

So the problem is, the Electron browser is not honoring the response from the pre-flight OPTIONS request the way Chrome is. Can't find anything on the web about what might be causing this.... any help appreciated.

[andrewryan1906]

OK,

I've done a bit more work and was able to identify the issue. I thought it was really weird that Electron accepted the CORS headers for GET/POST, but not PUT/DELETE. For giggles, I tried to delineate all of the CORS methods that were allowed, so I went to API Gateway and changed the CORS output from:

Access-Control-Allow-Methods: '*'

to

Access-Control-Allow-Methods: 'GET,PUT,POST,DELETE,OPTIONS'

And lo and behold, everything works. Not sure why this is, but I'm going to leave this issue open in case you have additional insights/comments.