Add support for JSDOM to JSIO

[armanbilge]

The JSDOM JSEnv runs in a sandbox within Node.js, so it has access to the same APIs via a sandbox-breaking technique. See:

• How can a script escape the sandbox? jsdom/jsdom#2729
• Implement polyfill for JSDOM scala-js/scala-js-macrotask-executor#17
• Add support for JSDOM JSEnv scoverage/scalac-scoverage-plugin#456

[valencik]

How would someone test that this works?

[armanbilge]

It's slightly annoying to setup, but we have to find a way to run the test suite in the JSDOM JSEnv in addition to Node.js.
https://github.com/scala-js/scala-js-env-jsdom-nodejs/

scoverage/scalac-scoverage-plugin#456 is one example of how to do that.

[armanbilge]

There we go. Enjoy your 1000+ lines of lockfiles :P

[armanbilge]

Confirmed that JSDOM fails in CI without my changes in #530.

[valencik]

Oh wow, thanks for that.

Is the idea that you could now run your munit tests in a browser environment?
I admit, I'm a tiny bit confused what this enables. It seems like using munit and jsdom was previously possible: https://github.com/scala-js/scala-js-env-jsdom-nodejs/#usage---writing-a-test

But this is different in that munit itself could run within the jsdom environment?

[armanbilge]

Yes that's right, it was already possible to use it as a test environment. But any file based features were not working (such as diffs and line numbers) because browsers don't have access to file system. Since JSDOM is a mere sandbox emulating the browser, we can break out to access the relevant APIs.

[armanbilge]

See also:

• partial error reporting using chromedriver #492

[armanbilge]

And also:

• Avoid relying on Node's fs when running in browser-based JSEnv  #247

[valencik]

This is really cool. Tested locally and everything works swell!

Just noting that this only runs the tests in the JSDOM environment in our CI, there isn't a new project within sbt that runs the tests.

You can manually run them in a sbt shell by changing your jsEnv:

set testsJS / jsEnv := {new org.scalajs.jsenv.jsdomnodejs.JSDOMNodeJSEnv}`

And then run the js tests with:
testsJS / test

[olafurpg]

LGTM it's great that we can support jsdom 👏