Tools: Initial import of check-examples script

check-examples/.eslintrc.js

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+module.exports = {
+    "extends": "google",
+    "env": {
+        "browser": true 
+    },
+    "parserOptions": {
+        "ecmaVersion": 2017
+    },
+    "parser": "babel-eslint",
+    "rules": {
+        "require-jsdoc": "off",
+        "eol-last":  "off",
+        "comma-dangle": "off",
+        "no-unused-vars": "off",
+        "quotes": "off",
+        "max-len": "off",
+    },
+    "plugins": [
+        "html"
+    ],
+};

check-examples/README.md

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+# Check Examples
+A script that extracts the example code snippets from the specification and
+runs a code linter on them.
+
+## Install and Run
+`$ npm install`
+`$ node check.js ../webrtc.html`
+
+## Self Linting
+Run the linter on the script itself with the same rules that are used for
+specification examples:
+`$ npm run linter`

check-examples/check.js

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+const fs = require('fs');
+const {spawn} = require('child_process');
+const htmlparser = require('htmlparser2');
+const Entities = require('html-entities').XmlEntities;
+
+const entities = new Entities();
+let isExampleText = false;
+let exampleCounter = 0;
+let nonPassingCounter = 0;
+
+const parser = new htmlparser.Parser({
+    onopentag: (tagName, attributes) => {
+        if (tagName === 'pre' && 'class' in attributes && attributes.class.includes('example')) {
+            isExampleText = true;
+        }
+    },
+    ontext: (text) => {
+        if (isExampleText) {
+            checkExample(text);
+            isExampleText = false;
+        }
+    },
+}, {decodeEntities: false});
+
+function printWithLineNumbers(str) {
+    let count = 1;
+    const out = str.replace(/^|\n/g, () => `\n${String(count++).padStart(3, '0')}  `);
+    console.log(out);
+}
+
+function checkExample(tagText) {
+    let text = entities.decode(tagText).trim();
+    const testName = `Example_${++exampleCounter}`;
+    const fileExt = text.includes('<script') ? 'html' : 'js';
+
+    const check = spawn('node_modules/.bin/eslint', [
+        '--stdin',
+        '--stdin-filename',
+        `${testName}.${fileExt}`, // A filename helps to load plugins
+    ]);
+
+    // If the "bare" code contains await statements it needs to be wrapped in an async function
+    if (fileExt != 'html' && text.includes('await ')) {
+        text = `async () => {\n${text}\n};`;
+    }
+
+    // ESLint doesn't seem to like anonymous objects
+    if (text.startsWith('{') && text.endsWith('}')) {
+        text = `temp = ${text};`;
+    }
+
+    check.stdin.setEncoding('utf-8');
+    check.stdin.write(text);
+    check.stdin.end();
+
+    function printOutput(data) {
+        console.log(`=== ${testName} ===`);
+        printWithLineNumbers(text);
+        console.log('=== Linter output ===');
+        console.log(data.toString());
+    }
+
+    check.stdout.on('data', printOutput);
+    check.stderr.on('data', printOutput);
+
+    check.on('close', (code) => {
+        if (code == 0) {
+            console.log(`${testName}: Passed`);
+        } else {
+            console.error(`${testName}: Linter process exited with code ${code}\n`);
+            nonPassingCounter++;
+        }
+        parser.resume();
+    });
+
+    parser.pause();
+}
+
+process.on('exit', () => {
+    const message = nonPassingCounter == 0 ? 'All examples passed'
+        : `${nonPassingCounter} of ${exampleCounter} examples did not pass`;
+    console.log(`\nSummary: ${message}`);
+});
+
+const filenameIndex = process.argv[0].includes('node') ? 2 : 1;
+if (process.argv.length < filenameIndex + 1) {
+    console.warn('Missing filename');
+    process.exit();
+}
+
+const filename = process.argv[filenameIndex];
+fs.readFile(filename, 'utf8', (err, data) => {
+    if (err) {
+        console.error(err.toString());
+        return;
+    }
+
+    console.info(`Checking ${filename}`);
+    parser.write(data);
+    parser.end();
+});

check-examples/package.json

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+{
+  "name": "check-examples",
+  "version": "1.0.0",
+  "description": "Validate example code snippets in a W3C specification.",
+  "main": "check.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "linter": "eslint check.js"
+  },
+  "author": "adambe",
+  "dependencies": {
+    "babel-eslint": "^8.0.1",
+    "eslint": "^4.9.0",
+    "eslint-plugin-html": "^3.2.2",
+    "html-entities": "^1.2.1",
+    "htmlparser2": "^3.9.2",
+    "eslint-config-google": "^0.9.1"
+  }
+}