doc: improve docs around running javascript tests

[iloveitaly]

As far as I could tell, this was not documented anywhere. These tips + examples would have been helpful for a first-time contributor like myself.

[nodejs-github-bot]

Review requested:

• @nodejs/tsc

[aduh95]

I don't think that's true, it runs the full test suite for me.

Suggested change

	A filter can be applied to only run specific tests:
	```bash
	make jstest test/parallel/test-debugger-pid.js test/sequential/test-debugger-pid.js test/sequential/test-debugger-launch.mjs
	```
	A filter can be applied to only run specific tests:
	```bash
	./tools/test.py test/parallel/test-debugger-pid.js test/sequential/test-debugger-pid
	```

[aduh95]

It won't run all the tests, as its name implies it's only a subset of them.

Suggested change

	All tests can be executed by running the `jstest` target:
	Running the `jstest` target will execute all the tests for the `node` binary:

[joyeecheung]

I think there is still a catch in this...that internet tests aren't run with make jstest 😂

[aduh95]

Suggested change

	All tests can be executed by running the `jstest` target:
	Running the `jstest` target will execute all the tests for the `node` binary
	except those which require internet access:

[aduh95]

Suggested change

	make jstest
	make jstest -j12

[GeoffreyBooth]

You could also add that filters can be used to run all the tests for a particular subsystem. A command I use a lot is:

tools/test.py --mode=release --timeout=30 es-module

To run all the ESM tests in about 8 seconds on my machine.

Really this is just a filter on the es-module folder; as a long-term goal it would be nice to gradually break up the parallel folder into various folders based on subsystem, so that as you’re working on a particular subsystem you can quickly re-run that system’s set of tests often, and then run the full test suite when you’re ready to commit or push.

[Trott]

Not blocking this pull request but a suggestion for someone motivated to do it: This PR might contain information that we don't have elsewhere, but we do have "how to run tests" information in both BUILDING.md and doc/contributing/pull-requests.md. Not blocking on this pull request for this, but it would probably be good to consolidate how-to-run-tests info in one place and then put links to the One True Source Of Information in the docs that we remove it from. Part of me wants to suggest putting it all in test/README.md, but any of the places where it exists now would be fine, including the one being created in this PR.

[aduh95]

as a long-term goal it would be nice to gradually break up the parallel folder into various folders based on subsystem, so that as you’re working on a particular subsystem you can quickly re-run that system’s set of tests often, and then run the full test suite when you’re ready to commit or push.

You can already run a subset of tests in the parallel folder:

$ tools/test.py test/parallel/test-crypto*
[00:05|% 100|+  60|-   0]: Done                                               

All tests passed.

[GeoffreyBooth]

You can already run a subset of tests in the parallel folder:

TIL! That's pretty cool. Still though, I think a more sensible organization would avoid having over a thousand files in a single folder.