Make jest-worker use jest-serializer

packages/jest-worker/package.json

@@ -8,6 +8,7 @@
   "license": "MIT",
   "main": "build/index.js",
   "dependencies": {
+    "jest-serializer": "^22.3.0",
     "merge-stream": "^1.0.1"
   }
 }

packages/jest-worker/src/__tests__/channel.test.js

@@ -0,0 +1,95 @@
+/**
+ * Copyright (c) 2018-present, Facebook, Inc. All rights reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+import EventEmitter from 'events';
+import Channel from '../channel';
+import serializer from 'jest-serializer';
+
+let stream;
+let channel;
+
+beforeEach(() => {
+  stream = Object.assign(new EventEmitter(), {
+    write: jest.fn(),
+  });
+
+  channel = new Channel(stream);
+});
+
+it('sends data prefixed with length', () => {
+  const data = {
+    bar: [0, true, '2'],
+    foo: 42,
+  };
+
+  const buffer = serializer.serialize(data);
+
+  channel.send(data);
+
+  // Verify that the length is sent first.
+  expect(stream.write.mock.calls[0]).toEqual([
+    new Buffer([buffer.length, 0, 0, 0]),
+  ]);
+
+  // Then the corresponding serialized message as a buffer.
+  expect(stream.write.mock.calls[1]).toEqual([buffer]);
+});
+
+it('processes a single message split into different buffers', () => {
+  const data = {
+    bar: [0, true, '2'],
+    foo: 42,
+  };
+
+  const message = serializer.serialize(data);
+  const received = jest.fn();
+
+  channel.on('message', received);
+
+  // Just received the length.
+  stream.emit('data', Buffer.from([message.length, 0, 0, 0]));
+  expect(received).not.toBeCalled();
+
+  // Now received half of the buffer.
+  stream.emit('data', message.slice(0, message.length / 2));
+  expect(received).not.toBeCalled();
+
+  // And now the full buffer.
+  stream.emit('data', message.slice(message.length / 2));
+  expect(received).toHaveBeenCalledTimes(1);
+
+  expect(received.mock.calls[0][0]).toEqual(data);
+});
+
+it('can process multiple messages into a single buffer', () => {
+  const data1 = {
+    bar: [0, true, '2'],
+    foo: 42,
+  };
+
+  const data2 = [null, 'red', {}];
+
+  const message1 = serializer.serialize(data1);
+  const message2 = serializer.serialize(data2);
+  const message = Buffer.allocUnsafe(8 + message1.length + message2.length);
+  const received = jest.fn();
+
+  message.writeUInt32LE(message1.length, 0);
+  message1.copy(message, 4);
+
+  message.writeUInt32LE(message2.length, 4 + message1.length);
+  message2.copy(message, 8 + message1.length);
+
+  channel.on('message', received);
+  stream.emit('data', message);
+
+  expect(received).toHaveBeenCalledTimes(2);
+  expect(received.mock.calls[0][0]).toEqual(data1);
+  expect(received.mock.calls[1][0]).toEqual(data2);
+});