Used for https://github.com/Microsoft/vscode/issues/43754

browser.js

const puppeteer = require('puppeteer');

/**
 * This is a thin wrapper so that we use a singleton of
 * the browser that puppeteer creates
 */
class Browser {
  setUp(done) {
    const puppeteerOpts = this.options && this.options.puppeteer ?
      this.options.puppeteer :
      {};

    puppeteer.launch(puppeteerOpts).then(async b => {
      this.setBrowser(b);
      done();
    });
  }

  setBrowser(b) {
    this.browser = b;
    const oldNewPage = this.browser.newPage.bind(this.browser);

    this.browser.newPage = async function () {
      const page = await oldNewPage();
      this.lastPage = page;

      await page.setViewport({ width:1024, height:800});        

      return page;
    };
  }

  setOptions(opts) {
    this.options = opts;
  }

  test(promise) {

    return (done) => {
      //In CLI or attach this works, from code 
      //  this.browser is undefined
      console.log(this.browser);

      promise(this.browser, this.options)
        .then(() => done()).catch(done);
    };
  }
}

/*
 * Create a new browser and use a proxy to pass
 * any puppeteer calls to the inner browser
 */
module.exports = new Proxy(new Browser(), {
  get: function(target, name) {
    return name in target ? target[name].bind(target) : target.browser[name];
  }
});