feat(validate/webidl): add Web IDL validator

[tidoust]

This adds an IDL validation step, enabled by default. The IDL gets extracted from the spec through Reffy and validated with WebIDL2.js.

The step gets skipped if no IDL can be extracted from the spec.

Enabling the step by default should not have any noticeable impact on "well-known" specs, typically those that are in browser-specs. In particular, the IDL patches that we currently need to maintain in Webref are for specs that do not use spec-prod, except for the DeviceOrientation Event specification, whose IDL fix is being tracked in w3c/deviceorientation#88.

@sidvishnoi, FYI, I note that, in order to test locally, and on top of the changes you suggested in #93 (comment), I also needed to:

1. Explicitly set the PUPPETEER_EXECUTABLE_PATH env variable to an empty string in src/build.ts line 182 through:

   process.env["PUPPETEER_EXECUTABLE_PATH"] = PUPPETEER_ENV.PUPPETEER_EXECUTABLE_PATH || '';
   

   ... as the code does not seem to like when the env variable is undefined.
2. Set the GITHUB_ENV and GITHUB_PATH env varibles to an empty string in test/index.test.ts line 11 instead of /dev/null (perhaps simply because I'm on a Windows machine)

This would fix #87.

[sidvishnoi]

@tidoust This looks great! 😍 Thanks for working on this! I'll do testing and review in day tomorrow.

---

I've quickly pushed two small changes to main branch:

• Run yarn lint to check for linting issues and yarn lint --write to autofix them (713c690).
• Use a cross platform null device in tests (4b53b84). Would love if you can test it on Windows.

[sidvishnoi]

Though, should we disable this check on ReSpec specs as ReSpec already does validation using webidl2?

[tidoust]

Use a cross platform null device in tests (4b53b84). Would love if you can test it on Windows.

Unless I'm missing something, that update does not work on Windows. The call to fs.existsSync done in the code of the @action/core returns false on Windows. FWIW, I tried to switch to Node.js v16.x in case there is some magic in that version that handles the null device but that does not change anything.

[tidoust]

Though, should we disable this check on ReSpec specs as ReSpec already does validation using webidl2?

When ReSpec detects invalid IDL, what happens in practice? If the build step fails, then we don't really need to add logic to the IDL validation step: it won't run since build fails. If the build still goes through with some reported errors, then I would actually prefer to keep the IDL validation in this step because it will actually block publication, which is what I think we want here: catch IDL errors early (typically in pull requests) so that they cannot get published in the first place.

[sidvishnoi]

By default, ReSpec build fails on IDL errors and action exits with error, so there's nothing to be done. But if BUILD_FAIL_ON: nothing is provided, build will pass regardless of errors - so we need IDL validation step only in this case. Though, that logic might require some work (as final toolchain isn't available to src/prepare-validate.ts yet), so lets leave it for now.

Unless I'm missing something, that update does not work on Windows.

Lets also skip it for now then 😄

[sidvishnoi]

[sidvishnoi]

Released in v2 ≡ v2.6.0 🎉