Simplify documentation linter

This patch simplifies documentation linter, basically
addressing the comments from #47.

References #14.

test/doclint/MDOutline.js

@@ -3,29 +3,39 @@ const commonmark = require('commonmark');
 const Browser = require('../../lib/Browser');
 
 class MDOutline {
-  constructor(text) {
-    this.classes = [];
-    this.html = MDOutline.compile(text);
-  }
-
-  static compile(text) {
+  /**
+   * @return {!MDOutline}
+   */
+  static async create(text) {
+    // Render markdown as HTML.
     const reader = new commonmark.Parser();
     const parsed = reader.parse(text);
     const writer = new commonmark.HtmlRenderer();
     const html = writer.render(parsed);
-    return html;
-  }
 
-  async collectHeadings() {
+    // Extract headings.
     const browser = new Browser({args: ['--no-sandbox']});
     const page = await browser.newPage();
-    await page.setContent(this.html);
-    this.headings = await page.evaluate(getTOCHeadings);
+    await page.setContent(html);
+    const headings = await page.evaluate(() => {
+      let headings = {};
+      let methods = [];
+      for (let header of document.body.querySelectorAll('h3,h4')) {
+        if (header.matches('h3')) {
+          methods = [];
+          headings[header.textContent] = methods;
+        } else {
+          methods.push(header.textContent);
+        }
+      }
+      return headings;
+    });
     await browser.close();
+    return new MDOutline(headings);
   }
 
-  buildClasses() {
-    const headings = this.headings;
+  constructor(headings) {
+    this.classes = [];
     const classHeading = /^class: (\w+)$/;
     const constructorRegex = /^new (\w+)\((.*)\)$/;
     const methodRegex = /^(\w+)\.(\w+)\((.*)\)$/;
@@ -68,18 +78,4 @@ class MDOutline {
   }
 }
 
-function getTOCHeadings(){
-  const headings = {};
-  document.querySelectorAll('h3').forEach((domainEl, i) => {
-    const methods = [];
-    let currElem = domainEl;
-    while ((currElem = currElem.nextElementSibling) && !currElem.matches('h3')) {
-      if (currElem.matches('h4'))
-        methods.push(currElem.textContent);
-    }
-    headings[domainEl.textContent] = methods;
-  });
-  return headings;
-}
-
 module.exports = MDOutline;

test/doclint/lint.js

@@ -9,11 +9,12 @@ const PROJECT_DIR = path.join(__dirname, '..', '..');
 const apiMdText = fs.readFileSync(path.join(PROJECT_DIR, 'docs', 'api.md'), 'utf8');
 
 let EXCLUDE_CLASSES = new Set([
-  'Helper',
+  'Connection',
   'FrameManager',
+  'Helper',
   'Navigator',
   'NetworkManager',
-  'Connection'
+  'ProxyStream'
 ]);
 
 let EXCLUDE_METHODS = new Set([
@@ -55,16 +56,15 @@ let mdClassesArray;
 
 beforeAll(SX(async function() {
   // Build up documentation from MD sources.
-  let mdOutline = new MDOutline(apiMdText);
-  await mdOutline.collectHeadings();
-  mdOutline.buildClasses();
+  let mdOutline = await MDOutline.create(apiMdText);
   mdClassesArray = mdOutline.classes;
 }));
 
 describe('table of contents', function() {
   it('should match markdown-toc\'s output', () => {
     const newApiMdText = markdownToc.insert(apiMdText);
-    expect(apiMdText === newApiMdText).toBe(true, 'markdown TOC is outdated, run `yarn generate-toc`');
+    if (apiMdText !== newApiMdText)
+      fail('markdown TOC is outdated, run `yarn generate-toc`');
   });
 });