Improve and extend test suite about three-elements

[hmans]

There will be tests. This library is a few days old. :)

Testing this is going to be interesting, and I will need to read up on the current state of the art of integration testing with WebGL. Please keep kicking my butt about this!

[hmans]

Thanks for pointing me towards @web/test-runner and @open-wc/testing. I've started adding tests to the library. What's there is still relatively simple, but it'll grow over time.

[daKmoR]

sweet - having the setup up and running is already a big step 👍

[CodyJasonBennett]

I'm curious if there's a way to test interactions in WebGL and WebXR here.

[hmans]

I'm curious if there's a way to test interactions in WebGL and WebXR here.

As far as I understand, testing that kind of stuff is really hard -- and mostly involves taking render snapshots and comparing them to catch regressions. It's definitely something I want to look deeper into.

[CodyJasonBennett]

It's a longshot, but I think we can focus on elements' lifecycles and DOM events for now.

[hmans]

Further work has been done here, especially in terms of moving things away from that big, almost-monolithic .html test, to smaller, case-specific .ts tests.

[hmans]

We now have a pretty solid test harness and are continuously adding new tests for added or changed features. I'm closing this ticket. Thanks for kicking my butt about this!