test: deliver colorful debug messages, do not pipe stdio (#3477)

test/runner/runner.js

@@ -184,9 +184,11 @@ class Worker extends EventEmitter {
       detached: false,
       env: {
         FORCE_COLOR: process.stdout.isTTY ? 1 : 0,
+        DEBUG_COLORS: process.stdout.isTTY ? 1 : 0,
         ...process.env
       },
-      stdio: ['ignore', 'pipe', 'pipe', 'ipc']
+      // Can't pipe since piping slows down termination for some reason.
+      stdio: ['ignore', 'ignore', 'ignore', 'ipc']
     });
     this.process.on('exit', () => this.emit('exit'));
     this.process.on('message', message => {
@@ -195,18 +197,23 @@ class Worker extends EventEmitter {
     });
     this.stdout = [];
     this.stderr = [];
-    this.process.stdout.on('data', data => {
+    this.on('stdout', data => {
       if (runner._options.dumpio)
         process.stdout.write(data);
       else
-        this.stdout.push(data.toString());
+        this.stdout.push(data);
     });
-
-    this.process.stderr.on('data', data => {
+    this.on('stderr', data => {
       if (runner._options.dumpio)
         process.stderr.write(data);
       else
-        this.stderr.push(data.toString());
+        this.stderr.push(data);
+    });
+    this.on('debug', data => {
+      if (runner._options.dumpio)
+        process.stderr.write(data + '\n');
+      else
+        this.stderr.push(data + '\n');
     });
   }
 

test/runner/worker.js

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-const path = require('path');
+const debug = require('debug');
 const Mocha = require('mocha');
 const { fixturesUI, fixturePool } = require('./fixturesUI');
 const { gracefullyCloseAll } = require('../../lib/server/processLauncher');
@@ -29,6 +29,18 @@ extendExpects();
 
 let closed = false;
 
+process.stdout.write = chunk => {
+  sendMessageToParent('stdout', chunk);
+};
+
+process.stderr.write = chunk => {
+  sendMessageToParent('stderr', chunk);
+};
+
+debug.log = data => {
+  sendMessageToParent('debug', data);
+};
+
 process.on('message', async message => {
   if (message.method === 'init')
     process.env.JEST_WORKER_ID = message.params.workerId;