Add a test framework to test the JS part of the course (#2471)

This is a first draft for a test framework for testing the JS part of
the book that is discussed in #2462

It is using [webdriverIO](https://webdriver.io/) and the webdriverIO
[Expect API](https://webdriver.io/docs/api/expect-webdriverio/) in
combination with [Mocha](https://mochajs.org/). WebdriverIO is taking
care of accessing the webpage with a real browser and can access the
state of the page so behavior can be asserted.

Currently only a small test for the speaker-notes implementation demos
the functionality.

The [Static Server
Service](https://webdriver.io/docs/static-server-service/) is used to
serve the book in a way that the test runner can access it.

A CI integration can look like https://webdriver.io/docs/githubactions/
and is implemented with a headless setup. In CI it uses the language
variable to set environment variable that configures where the built
book should be mounted from

---------

Co-authored-by: Martin Geisler <[email protected]>

.github/workflows/build.yml

@@ -181,6 +181,19 @@ jobs:
           MDBOOK_BOOK__LANGUAGE: ${{ matrix.language }}
         run: mdbook test
 
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 18
+      - name: Install test framework
+        run: npm install
+        working-directory: ./tests
+      - name: Test Javascript
+        run: npm test
+        env:
+          TEST_BOOK_DIR: ../book/comprehensive-rust-${{ matrix.language }}/html
+        working-directory: ./tests
+
   po-diff:
     name: Translation diff
     runs-on: ubuntu-latest

.gitignore

@@ -19,6 +19,7 @@ count.dat
 # Nodejs Files (dprint)
 node_modules/
 package.json
+!tests/package.json
 pnpm-lock.yaml
 
 # Crowdin Config (Contains API Keys)

tests/README.md

@@ -0,0 +1,20 @@
+# Testing Comprehensive Rust
+
+The course material contains JS code that can break and needs to be checked for
+functionality. Examples are `theme/speaker-notes.js` or `theme/book.js`.
+
+Comprehensive Rust is using [webdriverIO](https://webdriver.io/) and the
+[webdriverIO Expect API](https://webdriver.io/docs/api/expect-webdriverio/) in
+combination with [Mocha] (https://mochajs.org/). WebdriverIO is taking care of
+accessing the webpage with a real browser and can access the state of the page
+so behavior can be asserted.
+
+The [Static Server Service](https://webdriver.io/docs/static-server-service/) is
+used mainly in the [CI](../github/workflows/build.yml) to serve the book on port
+`localhost:8080` such that the test runner can access it. This mode is used when
+`npm start` or `npm test` is executed.
+
+For local testing and quick iterations it is possible to use `mdbook serve`
+which creates a small HTTP server on port 3000 by default. There is a special
+config that is invoked with `npm run test-mdbook` that uses
+`http://localhost:3000`