rustdoc: document JS/TS checks via tidy; move note out of GUI test doc

Author: ali90h

src/rustdoc-internals/rustdoc-gui-test-suite.md

@@ -7,34 +7,6 @@ For other rustdoc-specific test suites, see [Rustdoc test suites].
 
 These use a NodeJS-based tool called [`browser-UI-test`] that uses [puppeteer] to run tests in a headless browser and check rendering and interactivity. For information on how to write this form of test, see [`tests/rustdoc-gui/README.md`][rustdoc-gui-readme] as well as [the description of the `.goml` format][goml-script]
 
-### Rustdoc frontend checks in CI (ESLint & TypeScript)
-
-Rustdoc's JS/TS **linting and type-checking** are **not** performed by `compiletest`. In CI they run under the tidy "extra checks" step, which invokes ESLint and `tsc` on rustdoc's frontend sources.
-
-To reproduce locally (mirrors CI behavior for rustdoc's frontend suites):
-
-```bash
-./x.py test --stage 2 tests/rustdoc-js
-./x.py test --stage 2 tests/rustdoc-js-std
-./x.py test --stage 2 tests/rustdoc-gui
-```
-
-You can also run the linters directly in the frontend sources:
-
-```bash
-cd rust/src/librustdoc/html/static/js
-npm ci
-npx tsc -p tsconfig.json
-npx eslint .
-```
-
-**Notes**
-
-On macOS you may see small pixel/position diffs that fail some rustdoc-gui tests locally; CI's Linux baseline is authoritative.
-
-Running `npx tsc` directly depends on your local TypeScript environment (DOM vs Node types). Prefer the suites above when in doubt.
-
-In CI, these checks run inside the dedicated "tidy" job (see the "tidy" job in GitHub Actions). It installs tidy and runs `./x.py test tidy -vv`, which triggers the ESLint/TypeScript steps described above.
 
 [Rustdoc test suites]: ../tests/compiletest.md#rustdoc-test-suites
 [`browser-UI-test`]: https://github.com/GuillaumeGomez/browser-UI-test/

src/rustdoc.md

@@ -60,6 +60,17 @@ does is call the `main()` that's in this crate's `lib.rs`, though.)
 * Use `./x test tests/rustdoc*` to run the tests using a stage1
   rustdoc.
   * See [Rustdoc internals] for more information about tests.
+* Use `./x test tidy --extra-checks=js` to run ESLint/TSC checks on rustdoc's frontend code.
+
+### Frontend CI checks
+
+Rustdoc's JavaScript and TypeScript are checked by ESLint and `tsc` during CI, not by compiletest. These run as part of the tidy job:
+
+```bash
+./x.py test tidy --extra-checks=js
+```
+
+The `--extra-checks=js` flag enables the frontend linting that runs in CI.
 
 [`bootstrap.toml`]: ./building/how-to-build-and-run.md