🏗 Introduction of coverage-map task. (ampproject#29519)

* moved script to tasks and added package requirements

* lint fix

* progress on making task

* remove test.json

* additional lint fixes

* fixed according to comments

* several changes in coverage-map

* lint

* clarify description

* change to use async writefile

* review flag

* OK in window.scrollBy()

* lint

* added source-map-explorer to package.json

* Some changes based on feedback

* additional updated based on feedback

* small change

* added separate package.json

* package specific changes

* undo changes in root package.json

* added yarn.lock

* several changes

* revert yarn.lock

* lock file

* delete package-lock.json

* update gulpfile.js

* lazy importing

* revert change

* remove package-lock

* Update package.json

* yarn.lock

* prettify

* excluded coverage-map for getComputedStyle

* additional feedback

Co-authored-by: Derek Tse <[email protected]>

build-system/tasks/coverage-map/index.js

@@ -0,0 +1,119 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+const argv = require('minimist')(process.argv.slice(2));
+const fs = require('fs').promises;
+const log = require('fancy-log');
+const {dist} = require('../dist');
+const {installPackages} = require('../../common/utils');
+const {startServer, stopServer} = require('../serve');
+
+let puppeteer;
+let explore;
+
+const coverageJsonName = argv.json || 'coverage.json';
+const testUrl =
+  argv.url || 'http://localhost:8000/examples/everything.amp.html';
+const outHtml = argv.html || 'coverage.html';
+const scrollDistance = 100;
+
+async function collectCoverage() {
+  log(`Opening browser and navigating to ${testUrl}...`);
+  const browser = await puppeteer.launch({
+    defaultViewport: {width: 1200, height: 800},
+  });
+  const page = await browser.newPage();
+
+  // Enable JavaScript coverage
+  await page.coverage.startJSCoverage();
+  // Navigate to page
+  await page.goto(testUrl);
+  await page.waitFor(
+    () =>
+      !!document.querySelector('style[amp-runtime]') &&
+      !!document.body &&
+      getComputedStyle(document.body).visibility === 'visible'
+  );
+  log('Scrolling to the end of the page...');
+  await autoScroll(page);
+  log('Testing completed.');
+  const jsCoverage = await page.coverage.stopJSCoverage();
+  const data = JSON.stringify(jsCoverage);
+  log(`Writing to ${coverageJsonName} in dist/${coverageJsonName}...`);
+  await fs.writeFile(`dist/${coverageJsonName}`, data, () => {});
+  await browser.close();
+}
+
+// Source: https://github.com/chenxiaochun/blog/issues/38s
+async function autoScroll(page) {
+  await page.evaluate(async () => {
+    await new Promise((resolve, opt_) => {
+      let totalHeight = 0;
+      const distance = scrollDistance;
+      const timer = setInterval(() => {
+        const {scrollHeight} = document.body;
+        window./*OK*/ scrollBy(0, distance);
+        totalHeight += distance;
+
+        if (totalHeight >= scrollHeight) {
+          clearInterval(timer);
+          resolve();
+        }
+      }, 100);
+    });
+  });
+}
+
+async function generateMap() {
+  log(
+    `Generating heat map in dist/${outHtml}, based on ${coverageJsonName}...`
+  );
+  await explore('dist/v0.js', {
+    output: {format: 'html', filename: `${outHtml}`},
+    coverage: `dist/${coverageJsonName}`,
+    onlyMapped: true,
+  });
+}
+
+async function coverageMap() {
+  installPackages(__dirname);
+
+  puppeteer = require('puppeteer');
+  explore = require('source-map-explorer').explore;
+
+  await dist();
+  await startServer(
+    {host: 'localhost', port: 8000},
+    {quiet: true},
+    {compiled: true}
+  );
+  await collectCoverage();
+  await generateMap();
+  await stopServer();
+}
+
+module.exports = {coverageMap};
+
+coverageMap.description =
+  'Generates a code coverage "heat map" HTML visualization on v0.js based on code traversed during puppeteer test via source map explorer';
+
+coverageMap.flags = {
+  json:
+    '  Customize the name of the JSON output from puppeteer (out.json by default).',
+  url:
+    '  Set the URL for puppeteer testing, starting with  "http://localhost:8000..." (http://localhost:8000/examples/everything.amp.html by default).',
+  html:
+    '  Customize the name of the HTML output from source map explorer (out.html by default).',
+};

build-system/tasks/coverage-map/package.json

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+{
+  "private": true,
+  "name": "gulp-coverage-map",
+  "version": "0.1.0",
+  "description": "Gulp coverage map.",
+  "dependencies": {
+    "puppeteer": "5.2.1",
+    "source-map-explorer": "2.4.2"
+  }
+}