fix: restarted browsers not running tests (#3233)

* fix: restarted browsers not running tests

Currently whenever a browser disconnects completely (no socket.io connection loss), the launcher is instructed to "restart" the browser. Whenever the restarted browser now tries to "register" again, Karma considers the browser instance to be still executing and doesn't do anything about it (except setting the state to `EXECUTING` again).

This means that the browser is in the state of executing, but
practically it does nothing just waits. Resulting another disconnect
(repeat here).

* test: add unit test that covers disconnected restarted browsers

* fixup! test: add unit test that covers disconnected restarted browsers

Address feedback

* fixup! test: add unit test that covers disconnected restarted browsers

Improve comments & log messages

Author: devversion

client/karma.js

@@ -14,6 +14,11 @@ function Karma (socket, iframe, opener, navigator, location) {
   var resultsBufferLimit = 50
   var resultsBuffer = []
 
+  // This variable will be set to "true" whenever the socket lost connection and was able to
+  // reconnect to the Karma server. This will be passed to the Karma server then, so that
+  // Karma can differentiate between a socket client reconnect and a full browser reconnect.
+  var socketReconnect = false
+
   this.VERSION = constant.VERSION
   this.config = {}
 
@@ -227,20 +232,27 @@ function Karma (socket, iframe, opener, navigator, location) {
     this.complete()
   }.bind(this))
 
-  // report browser name, id
+  // Report the browser name and Id. Note that this event can also fire if the connection has
+  // been temporarily lost, but the socket reconnected automatically. Read more in the docs:
+  // https://socket.io/docs/client-api/#Event-%E2%80%98connect%E2%80%99
   socket.on('connect', function () {
     socket.io.engine.on('upgrade', function () {
       resultsBufferLimit = 1
     })
     var info = {
       name: navigator.userAgent,
-      id: browserId
+      id: browserId,
+      isSocketReconnect: socketReconnect
     }
     if (displayName) {
       info.displayName = displayName
     }
     socket.emit('register', info)
   })
+
+  socket.on('reconnect', function () {
+    socketReconnect = true
+  })
 }
 
 module.exports = Karma

lib/browser.js

@@ -7,8 +7,8 @@ const logger = require('./logger')
 const CONNECTED = 'CONNECTED' // The browser is connected but not yet been commanded to execute tests.
 const CONFIGURING = 'CONFIGURING' // The browser has been told to execute tests; it is configuring before tests execution.
 const EXECUTING = 'EXECUTING' // The browser is executing the tests.
-const EXECUTING_DISCONNECTED = 'EXECUTING_DISCONNECTED' // The browser is executing the tests, but temporarily disconnect (waiting for reconnecting).
-const DISCONNECTED = 'DISCONNECTED' // The browser got permanently disconnected (being removed from the collection and destroyed).
+const EXECUTING_DISCONNECTED = 'EXECUTING_DISCONNECTED' // The browser is executing the tests, but temporarily disconnect (waiting for socket reconnecting).
+const DISCONNECTED = 'DISCONNECTED' // The browser got completely disconnected (e.g. browser crash) and can be only restored with a restart of execution.
 
 class Browser {
   constructor (id, fullName, collection, emitter, socket, timer, disconnectDelay, noActivityTimeout) {
@@ -121,15 +121,21 @@ class Browser {
 
   reconnect (newSocket) {
     if (this.state === EXECUTING_DISCONNECTED) {
-      this.log.debug(`Reconnected on ${newSocket.id}.`)
+      this.log.debug(`Lost socket connection, but browser continued to execute. Reconnected ` +
+        `on socket ${newSocket.id}.`)
       this.setState(EXECUTING)
     } else if ([CONNECTED, CONFIGURING, EXECUTING].includes(this.state)) {
-      this.log.debug(`New connection ${newSocket.id} (already have ${this.getActiveSocketsIds()})`)
+      this.log.debug(`Rebinding to new socket ${newSocket.id} (already have ` +
+        `${this.getActiveSocketsIds()})`)
     } else if (this.state === DISCONNECTED) {
-      this.log.info(`Connected on socket ${newSocket.id} with id ${this.id}`)
+      this.log.info(`Disconnected browser returned on socket ${newSocket.id} with id ${this.id}.`)
       this.setState(CONNECTED)
 
-      this.collection.add(this)
+      // Since the disconnected browser is already part of the collection and we want to
+      // make sure that the server can properly handle the browser like it's the first time
+      // connecting this browser (as we want a complete new execution), we need to emit the
+      // following events:
+      this.emitter.emit('browsers_change', this.collection)
       this.emitter.emit('browser_register', this)
     }
 

lib/server.js

@@ -232,10 +232,20 @@ class Server extends KarmaEventEmitter {
         let newBrowser = info.id ? (capturedBrowsers.getById(info.id) || singleRunBrowsers.getById(info.id)) : null
 
         if (newBrowser) {
+          // By default if a browser disconnects while still executing, we assume that the test
+          // execution still continues because just the socket connection has been terminated. Now
+          // since we know whether this is just a socket reconnect or full client reconnect, we
+          // need to update the browser state accordingly. This is necessary because in case a
+          // browser crashed and has been restarted, we need to start with a fresh execution.
+          if (!info.isSocketReconnect) {
+            newBrowser.setState(Browser.STATE_DISCONNECTED)
+          }
+
           newBrowser.reconnect(socket)
 
-          // We are restarting a previously disconnected browser.
-          if (newBrowser.state === Browser.STATE_DISCONNECTED && config.singleRun) {
+          // Since not every reconnected browser is able to continue with its previous execution,
+          // we need to start a new execution in case a browser has restarted and is now idling.
+          if (newBrowser.state === Browser.STATE_CONNECTED && config.singleRun) {
             newBrowser.execute(config.client)
           }
         } else {

test/client/karma.spec.js

@@ -147,6 +147,15 @@ describe('Karma', function () {
     assert(spyInfo.called)
   })
 
+  it('should mark "register" event for reconnected socket', function () {
+    socket.on('register', sinon.spy(function (info) {
+      assert(info.isSocketReconnect === true)
+    }))
+
+    socket.emit('reconnect')
+    socket.emit('connect')
+  })
+
   it('should report browser id', function () {
     windowLocation.search = '?id=567'
     socket = new MockSocket()

test/unit/browser.spec.js

@@ -297,6 +297,19 @@ describe('Browser', () => {
 
       expect(browser.isConnected()).to.equal(true)
     })
+
+    it('should not add a disconnected browser to the collection multiple times', () => {
+      browser = new Browser('id', 'Chrome 25.0', collection, emitter, socket, null, 10)
+      browser.init()
+
+      expect(collection.length).to.equal(1)
+
+      browser.state = Browser.STATE_DISCONNECTED
+
+      browser.reconnect(mkSocket())
+
+      expect(collection.length).to.equal(1)
+    })
   })
 
   describe('onResult', () => {

test/unit/server.spec.js

@@ -2,6 +2,7 @@ const Server = require('../../lib/server')
 const BundleUtils = require('../../lib/utils/bundle-utils')
 const NetUtils = require('../../lib/utils/net-utils')
 const BrowserCollection = require('../../lib/browser_collection')
+const Browser = require('../../lib/browser')
 
 describe('server', () => {
   let mockConfig
@@ -10,13 +11,15 @@ describe('server', () => {
   let fileListOnReject
   let mockLauncher
   let mockWebServer
+  let mockServerSocket
   let mockSocketServer
   let mockBoundServer
   let mockExecutor
   let doneSpy
   let server = mockConfig = browserCollection = webServerOnError = null
   let fileListOnResolve = fileListOnReject = mockLauncher = null
   let mockFileList = mockWebServer = mockSocketServer = mockExecutor = doneSpy = null
+  let mockSocketEventListeners = new Map()
 
   // Use regular function not arrow so 'this' is mocha 'this'.
   beforeEach(function () {
@@ -67,14 +70,21 @@ describe('server', () => {
       kill: () => true
     }
 
+    mockServerSocket = {
+      id: 'socket-id',
+      on: (name, handler) => mockSocketEventListeners.set(name, handler),
+      emit: () => {},
+      removeListener: () => {}
+    }
+
     mockSocketServer = {
       close: () => {},
       flashPolicyServer: {
         close: () => {}
       },
       sockets: {
         sockets: {},
-        on: () => {},
+        on: (name, handler) => handler(mockServerSocket),
         emit: () => {},
         removeAllListeners: () => {}
       }
@@ -277,4 +287,44 @@ describe('server', () => {
       }
     })
   })
+
+  describe('reconnecting browser', () => {
+    let mockBrowserSocket
+
+    beforeEach(() => {
+      browserCollection = new BrowserCollection(server)
+      server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneSpy)
+
+      mockBrowserSocket = {
+        id: 'browser-socket-id',
+        on: () => {},
+        emit: () => {}
+      }
+    })
+
+    it('should re-configure disconnected browser which has been restarted', () => {
+      const testBrowserId = 'my-id'
+      const browser = new Browser(testBrowserId, 'Chrome 19.0', browserCollection, server,
+        mockBrowserSocket, null, 0)
+      const registerFn = mockSocketEventListeners.get('register')
+
+      browser.init()
+      browserCollection.add(browser)
+
+      // We assume that our browser was running when it disconnected randomly.
+      browser.setState(Browser.STATE_EXECUTING_DISCONNECTED)
+
+      // We now simulate a "connect" event from the Karma client where it registers
+      // a previous browser that disconnected while executing. Usually if it was just a
+      // socket.io reconnect, we would not want to restart the execution, but since this is
+      // a complete reconnect, we want to configure the browser and start a new execution.
+      registerFn({
+        name: 'fake-name',
+        id: testBrowserId,
+        isSocketReconnect: false
+      })
+
+      expect(browser.state).to.equal(Browser.STATE_CONFIGURING)
+    })
+  })
 })

yarn.lock

@@ -2795,6 +2795,11 @@ flat-cache@^1.2.1:
     graceful-fs "^4.1.2"
     write "^0.2.1"
 
+flatted@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/flatted/-/flatted-2.0.0.tgz#55122b6536ea496b4b44893ee2608141d10d9916"
+  integrity sha512-R+H8IZclI8AAkSBRQJLVOsxwAoHd6WC40b4QTNWIjzAa6BXOBfQcM587MXDTVPeYaopFNWHUFLx7eNmHDSxMWg==
+
 for-in@^1.0.1, for-in@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/for-in/-/for-in-1.0.2.tgz#81068d295a8142ec0ac726c6e2200c30fb6d5e80"
@@ -4216,11 +4221,6 @@ json-stringify-safe@^5.0.1, json-stringify-safe@~5.0.1:
   resolved "https://registry.yarnpkg.com/json-stringify-safe/-/json-stringify-safe-5.0.1.tgz#1296a2d58fd45f19a0f6ce01d65701e2c735b6eb"
   integrity sha1-Epai1Y/UXxmg9s4B1lcB4sc1tus=
 
-json3@^3.3.2:
-  version "3.3.2"
-  resolved "https://registry.yarnpkg.com/json3/-/json3-3.3.2.tgz#3c0434743df93e2f5c42aee7b19bcb483575f4e1"
-  integrity sha1-PAQ0dD35Pi9cQq7nsZvLSDV19OE=
-
 jsonfile@^3.0.0:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/jsonfile/-/jsonfile-3.0.1.tgz#a5ecc6f65f53f662c4415c7675a0331d0992ec66"
@@ -4583,6 +4583,11 @@ lodash@^4.0.0, lodash@^4.14.0, lodash@^4.16.6, lodash@^4.17.2, lodash@^4.17.4, l
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.4.tgz#78203a4d1c328ae1d86dca6460e369b57f4055ae"
   integrity sha1-eCA6TRwyiuHYbcpkYONptX9AVa4=
 
+lodash@^4.17.5:
+  version "4.17.11"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.11.tgz#b39ea6229ef607ecd89e2c8df12536891cac9b8d"
+  integrity sha512-cQKh8igo5QUhZ7lg38DYWAxMvjSAKG0A8wGSVimP07SIUEK2UO+arSRKbRZWtelMtN5V0Hkwh5ryOto/SshYIg==
+
 lodash@~4.3.0:
   version "4.3.0"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.3.0.tgz#efd9c4a6ec53f3b05412429915c3e4824e4d25a4"
@@ -4641,10 +4646,13 @@ lower-case@^1.1.1:
   resolved "https://registry.yarnpkg.com/lower-case/-/lower-case-1.1.4.tgz#9a2cabd1b9e8e0ae993a4bf7d5875c39c42e8eac"
   integrity sha1-miyr0bno4K6ZOkv31YdcOcQujqw=
 
-lru-cache@2.2.x:
-  version "2.2.4"
-  resolved "https://registry.yarnpkg.com/lru-cache/-/lru-cache-2.2.4.tgz#6c658619becf14031d0d0b594b16042ce4dc063d"
-  integrity sha1-bGWGGb7PFAMdDQtZSxYELOTcBj0=
+lru-cache@4.1.x:
+  version "4.1.5"
+  resolved "https://registry.yarnpkg.com/lru-cache/-/lru-cache-4.1.5.tgz#8bbe50ea85bed59bc9e33dcab8235ee9bcf443cd"
+  integrity sha512-sWZlbEP2OsHNkXrMl5GYk/jKk70MBng6UU4YI/qGDYbgf6YbP4EvmqISbXCoJiRKs+1bSpFHVgQxvJ17F2li5g==
+  dependencies:
+    pseudomap "^1.0.2"
+    yallist "^2.1.2"
 
 lru-cache@^4.0.1:
   version "4.1.1"
@@ -6277,10 +6285,10 @@ signal-exit@^3.0.0, signal-exit@^3.0.2:
   resolved "https://registry.yarnpkg.com/signal-exit/-/signal-exit-3.0.2.tgz#b5fdc08f1287ea1178628e415e25132b73646c6d"
   integrity sha1-tf3AjxKH6hF4Yo5BXiUTK3NkbG0=
 
-sinon-chai@^2.7.0:
-  version "2.14.0"
-  resolved "https://registry.yarnpkg.com/sinon-chai/-/sinon-chai-2.14.0.tgz#da7dd4cc83cd6a260b67cca0f7a9fdae26a1205d"
-  integrity sha512-9stIF1utB0ywNHNT7RgiXbdmen8QDCRsrTjw+G9TgKt1Yexjiv8TOWZ6WHsTPz57Yky3DIswZvEqX8fpuHNDtQ==
+sinon-chai@^3.0.0:
+  version "3.3.0"
+  resolved "https://registry.yarnpkg.com/sinon-chai/-/sinon-chai-3.3.0.tgz#8084ff99451064910fbe2c2cb8ab540c00b740ea"
+  integrity sha512-r2JhDY7gbbmh5z3Q62pNbrjxZdOAjpsqW/8yxAZRSqLZqowmfGZPGUZPFf3UX36NLis0cv8VEM5IJh9HgkSOAA==
 
 sinon@^6.1.5:
   version "6.3.5"
@@ -7149,12 +7157,12 @@ use@^3.1.0:
   dependencies:
     kind-of "^6.0.2"
 
-useragent@2.2.1:
-  version "2.2.1"
-  resolved "https://registry.yarnpkg.com/useragent/-/useragent-2.2.1.tgz#cf593ef4f2d175875e8bb658ea92e18a4fd06d8e"
-  integrity sha1-z1k+9PLRdYdei7ZY6pLhik/QbY4=
+useragent@2.3.0:
+  version "2.3.0"
+  resolved "https://registry.yarnpkg.com/useragent/-/useragent-2.3.0.tgz#217f943ad540cb2128658ab23fc960f6a88c9972"
+  integrity sha512-4AoH4pxuSvHCjqLO04sU6U/uE65BYza8l/KKBS0b0hnUPWi+cQ2BpeTEwejCSx9SPV5/U03nniDTrWx5NrmKdw==
   dependencies:
-    lru-cache "2.2.x"
+    lru-cache "4.1.x"
     tmp "0.0.x"
 
 util-arity@^1.0.2: