refactor: devtools log (#1669)

* contain in driver, s/MessageLog/DevtoolsLog

lighthouse-core/gather/connections/connection.js

@@ -18,7 +18,6 @@
 
 const EventEmitter = require('events').EventEmitter;
 const log = require('../../lib/log.js');
-const MessageLog = require('./message-log');
 
 class Connection {
 
@@ -27,7 +26,6 @@ class Connection {
     /** @type {!Map<number, {resolve: function(*), reject: function(*), method: string}>}*/
     this._callbacks = new Map();
     this._eventEmitter = new EventEmitter();
-    this.log = new MessageLog();
   }
 
   /**
@@ -111,7 +109,6 @@ class Connection {
       }));
     }
 
-    this.log.record(object);
     log.formatProtocol('<= event',
         {method: object.method, params: object.params}, 'verbose');
     this.emitNotification(object.method, object.params);

lighthouse-core/gather/connections/message-log.js → lighthouse-core/gather/devtools-log.js

@@ -16,14 +16,23 @@
  */
 'use strict';
 
-class MessageLog {
-  constructor() {
+/**
+ * @fileoverview This class saves all protocol messages whose method match a particular
+ *    regex filter. Used when saving assets for later analysis by another tool such as
+ *    Webpagetest.
+ */
+class DevtoolsLog {
+  /**
+   * @param {RegExp=} regexFilter
+   */
+  constructor(regexFilter) {
+    this._filter = regexFilter;
     this._messages = [];
     this._isRecording = false;
   }
 
   /**
-   * @return {!Array<Object>}
+   * @return {!Array<{method: string, params: !Object}>}
    */
   get messages() {
     return this._messages;
@@ -42,13 +51,14 @@ class MessageLog {
   }
 
   /**
-   * @param {{method: string, params: Object}} message
+   * Records a message if method matches filter and recording has been started.
+   * @param {{method: string, params: !Object}} message
    */
   record(message) {
-    if (this._isRecording && /^(Page|Network)\./.test(message.method)) {
+    if (this._isRecording && (!this._filter || this._filter.test(message.method))) {
       this._messages.push(message);
     }
   }
 }
 
-module.exports = MessageLog;
+module.exports = DevtoolsLog;

lighthouse-core/gather/driver.js

@@ -23,6 +23,7 @@ const EventEmitter = require('events').EventEmitter;
 const URL = require('../lib/url-shim');
 
 const log = require('../lib/log.js');
+const DevtoolsLog = require('./devtools-log');
 
 const MAX_WAIT_FOR_FULLY_LOADED = 25 * 1000;
 const PAUSE_AFTER_LOAD = 500;
@@ -37,7 +38,12 @@ class Driver {
     this._traceCategories = Driver.traceCategories;
     this._eventEmitter = new EventEmitter();
     this._connection = connection;
-    connection.on('notification', event => this._eventEmitter.emit(event.method, event.params));
+    // currently only used by WPT where just Page and Network are needed
+    this._devtoolsLog = new DevtoolsLog(/^(Page|Network)\./);
+    connection.on('notification', event => {
+      this._devtoolsLog.record(event);
+      this._eventEmitter.emit(event.method, event.params);
+    });
     this.online = true;
     this._domainEnabledCounts = new Map();
   }
@@ -62,8 +68,11 @@ class Driver {
     ];
   }
 
+  /**
+   * @return {!Array<{method: string, params: !Object}>}
+   */
   get devtoolsLog() {
-    return this._connection.log.messages;
+    return this._devtoolsLog.messages;
   }
 
   /**
@@ -575,8 +584,8 @@ class Driver {
       throw new Error('DOM domain enabled when starting trace');
     }
 
-    this._connection.log.reset();
-    this._connection.log.beginRecording();
+    this._devtoolsLog.reset();
+    this._devtoolsLog.beginRecording();
 
     // Enable Page domain to wait for Page.loadEventFired
     return this.sendCommand('Page.enable')
@@ -587,7 +596,7 @@ class Driver {
     return new Promise((resolve, reject) => {
       // When the tracing has ended this will fire with a stream handle.
       this.once('Tracing.tracingComplete', streamHandle => {
-        this._connection.log.endRecording();
+        this._devtoolsLog.endRecording();
         this._readTraceFromStream(streamHandle)
             .then(traceContents => resolve(traceContents), reject);
       });

lighthouse-core/test/gather/connections/message-log-test.js → lighthouse-core/test/gather/devtools-log-test.js

@@ -18,15 +18,15 @@
 /* eslint-env mocha */
 
 const assert = require('assert');
-const MessageLog = require('../../../gather/connections/message-log');
+const DevtoolsLog = require('../../gather/devtools-log');
 
-describe('MessageLog', () => {
+describe('DevtoolsLog', () => {
   let messageLog;
   const pageMsg = {method: 'Page.frameStartedLoading'};
   const networkMsg = {method: 'Network.requestWillBeSent'};
   const otherMsg = {method: 'Storage.cleared'};
 
-  beforeEach(() => messageLog = new MessageLog());
+  beforeEach(() => messageLog = new DevtoolsLog(/^(Page|Network)/));
 
   it('returns an array', () => {
     assert.deepEqual(messageLog.messages, []);
@@ -42,7 +42,7 @@ describe('MessageLog', () => {
     assert.equal(messageLog.messages[0].method, networkMsg.method);
   });
 
-  it('does not record non-Network/Page events', () => {
+  it('does not record non-matching events', () => {
     messageLog.beginRecording();
     messageLog.record(pageMsg); // will record
     messageLog.record(networkMsg); // will record
@@ -52,6 +52,15 @@ describe('MessageLog', () => {
     assert.equal(messageLog.messages[0].method, pageMsg.method);
   });
 
+  it('records everything when no filter provided', () => {
+    messageLog = new DevtoolsLog();
+    messageLog.beginRecording();
+    messageLog.record(pageMsg);
+    messageLog.record(networkMsg);
+    messageLog.record(otherMsg);
+    assert.equal(messageLog.messages.length, 3);
+  });
+
   it('resets properly', () => {
     messageLog.beginRecording();
     messageLog.record(pageMsg);