add getSpecs.js for gfm

package.json

@@ -30,6 +30,7 @@
   ],
   "devDependencies": {
     "@markedjs/html-differ": "^2.0.1",
+    "cheerio": "^1.0.0-rc.3",
     "commonmark": "0.x",
     "eslint": "^5.15.1",
     "eslint-config-standard": "^12.0.0",

test/specs/gfm/getSpecs.js

@@ -0,0 +1,44 @@
+const fetch = require('node-fetch');
+const cheerio = require('cheerio');
+const marked = require('../../../');
+const htmlDiffer = require('../../helpers/html-differ.js');
+const fs = require('fs');
+
+fetch('https://github.github.com/gfm/')
+  .then(res => res.text())
+  .then(html => cheerio.load(html))
+  .then($ => {
+    const version = $('.version').text().match(/\d+\.\d+/)[0];
+    if (!version) {
+      throw new Error('No version found');
+    }
+    const specs = [];
+    $('.extension').each((i, ext) => {
+      const section = $('.definition', ext).text().trim().replace(/^\d+\.\d+(.*?) \(extension\)[\s\S]*$/, '$1');
+      $('.example', ext).each((j, exa) => {
+        const example = $(exa).attr('id').replace(/\D/g, '');
+        const markdown = $('.language-markdown', exa).text().trim();
+        const html = $('.language-html', exa).text().trim();
+        specs.push({
+          section,
+          html,
+          markdown,
+          example
+        });
+      });
+    });
+
+    return [version, specs];
+  })
+  .then(([version, specs]) => {
+    specs.forEach(spec => {
+      const html = marked(spec.markdown, {gfm: true});
+      if (!htmlDiffer.isEqual(html, spec.html)) {
+        spec.shouldFail = true;
+      }
+    });
+    fs.writeFileSync(`gfm.${version}.json`, JSON.stringify(specs, null, 2) + '\n');
+  })
+  .catch((err) => {
+    console.error(err);
+  });