fix(Launcher): fix dumpio bug (#2071)

This patch fixes `dumpio` launcher option.

Fixes #2046

lib/Launcher.js

@@ -100,10 +100,9 @@ class Launcher {
     if (Array.isArray(options.args))
       chromeArguments.push(...options.args);
 
-    const stdio = options.dumpio ? ['inherit', 'inherit', 'inherit'] : ['pipe', 'pipe', 'pipe'];
+    const stdio = ['pipe', 'pipe', 'pipe'];
     if (options.appMode)
       stdio.push('pipe', 'pipe');
-
     const chromeProcess = childProcess.spawn(
         chromeExecutable,
         chromeArguments,
@@ -114,6 +113,11 @@ class Launcher {
         }
     );
 
+    if (options.dumpio) {
+      chromeProcess.stderr.pipe(process.stderr);
+      chromeProcess.stdout.pipe(process.stdout);
+    }
+
     let chromeClosed = false;
     const waitForChromeToClose = new Promise((fulfill, reject) => {
       chromeProcess.once('close', () => {

test/fixtures/dumpio.js

@@ -0,0 +1,9 @@
+(async() => {
+  const [, , puppeteerRoot, options, emptyPage, dumpioTextToLog] = process.argv;
+  const browser = await require(puppeteerRoot).launch(JSON.parse(options));
+  const page = await browser.newPage();
+  await page.goto(emptyPage);
+  await page.evaluate(_dumpioTextToLog => console.log(_dumpioTextToLog), dumpioTextToLog);
+  await page.close();
+  await browser.close();
+})();

test/test.js

@@ -271,6 +271,18 @@ describe('Puppeteer', function() {
       const args = puppeteer.defaultArgs();
       expect(args).toContain('--no-first-run');
     });
+    it('should dump browser process stderr', async({server}) => {
+      const dumpioTextToLog = 'MAGIC_DUMPIO_TEST';
+      let dumpioData = '';
+      const {spawn} = require('child_process');
+      const options = Object.assign({dumpio: true}, defaultBrowserOptions);
+      const res = spawn('node',
+          [path.join(__dirname, 'fixtures', 'dumpio.js'), PROJECT_ROOT, JSON.stringify(options), server.EMPTY_PAGE, dumpioTextToLog]);
+      res.stderr.on('data', data => dumpioData += data.toString('utf8'));
+      await new Promise(resolve => res.on('close', resolve));
+
+      expect(dumpioData).toContain(dumpioTextToLog);
+    });
   });
   describe('Puppeteer.connect', function() {
     it('should be able to connect multiple times to the same browser', async({server}) => {