feat(config): socket.io server pingTimeout config option.

docs/config/01-configuration-file.md

@@ -59,10 +59,10 @@ Under the hood Karma uses ts-node to transpile TypeScript to JavaScript. If the
 Create a JavaScript configuration file that overrides the module format.
 ```javascript
 // karma.conf.js
-require('ts-node').register({ 
-  compilerOptions: { 
-    module: 'commonjs' 
-  } 
+require('ts-node').register({
+  compilerOptions: {
+    module: 'commonjs'
+  }
 });
 require('./karma.conf.ts');
 ```
@@ -678,6 +678,14 @@ Note: Just about all additional reporters in Karma (other than progress) require
 
 The CLI option should be a path to a file that exports the format function.  This can be a function exported at the root of the module or an export named `formatError`.
 
+## pingTimeout
+**Type** Number
+
+**Default** 5000
+
+**Description** Socket.io pingTimeout in ms, https://socket.io/docs/server-api/#new-Server-httpServer-options.
+Very slow networks may need values up to 60000. Larger values delay discovery of deadlock in tests or browser crashes.
+
 ## restartOnFileChange
 **Type:** Boolean
 

lib/config.js

@@ -204,6 +204,10 @@ function normalizeConfig (config, configFilePath) {
     assert(helper.isNumber(config.browserSocketTimeout), 'Invalid configuration: browserSocketTimeout option must be a number.')
   }
 
+  if (config.pingTimeout) {
+    assert(helper.isNumber(config.pingTimeout), 'Invalid configuration: pingTimeout option must be a number.')
+  }
+
   const defaultClient = config.defaultClient || {}
   Object.keys(defaultClient).forEach(function (key) {
     const option = config.client[key]
@@ -299,6 +303,7 @@ class Config {
     this.singleRun = false
     this.browsers = []
     this.captureTimeout = 60000
+    this.pingTimeout = 5000
     this.proxies = {}
     this.proxyValidateSSL = true
     this.preprocessors = {}

lib/server.js

@@ -44,7 +44,9 @@ function createSocketIoServer (webServer, executor, config) {
     destroyUpgrade: false,
     path: config.urlRoot + 'socket.io/',
     transports: config.transports,
-    forceJSONP: config.forceJSONP
+    forceJSONP: config.forceJSONP,
+    // Default is 5000 in socket.io v2.x.
+    pingTimeout: config.pingTimeout || 5000
   })
 
   // hack to overcome circular dependency

test/unit/config.spec.js

@@ -383,6 +383,15 @@ describe('config', () => {
 
       expect(invalid).to.throw('Invalid configuration: formatError option must be a function.')
     })
+
+    it('should prevent non-numeric input for numeric options', () => {
+      const invalid = function () {
+        normalizeConfigWithDefaults({
+          pingTimeout: '10000'
+        })
+      }
+      expect(invalid).to.throw('Invalid configuration: pingTimeout option must be a number.')
+    })
   })
 
   describe('createPatternObject', () => {