diff --git a/lib/server.js b/lib/server.js
index 804745088..ff03553eb 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -102,12 +102,6 @@ class Server extends KarmaEventEmitter {
     this._injector = new di.Injector(modules)
   }
 
-  dieOnError (error) {
-    this.log.error(error)
-    process.exitCode = 1
-    process.kill(process.pid, 'SIGINT')
-  }
-
   async start () {
     const config = this.get('config')
     try {
@@ -122,7 +116,8 @@ class Server extends KarmaEventEmitter {
       config.port = this._boundServer.address().port
       await this._injector.invoke(this._start, this)
     } catch (err) {
-      this.dieOnError(`Server start failed on port ${config.port}: ${err}`)
+      this.log.error(`Server start failed on port ${config.port}: ${err}`)
+      this._close(1)
     }
   }
 
@@ -187,7 +182,8 @@ class Server extends KarmaEventEmitter {
     let singleRunBrowserNotCaptured = false
 
     webServer.on('error', (err) => {
-      this.dieOnError(`Webserver fail ${err}`)
+      this.log.error(`Webserver fail ${err}`)
+      this._close(1)
     })
 
     const afterPreprocess = () => {
@@ -206,7 +202,8 @@ class Server extends KarmaEventEmitter {
           })
         }
         if (this.loadErrors.length > 0) {
-          this.dieOnError(new Error(`Found ${this.loadErrors.length} load error${this.loadErrors.length === 1 ? '' : 's'}`))
+          this.log.error(new Error(`Found ${this.loadErrors.length} load error${this.loadErrors.length === 1 ? '' : 's'}`))
+          this._close(1)
         }
       })
     }
@@ -302,9 +299,9 @@ class Server extends KarmaEventEmitter {
       }
     })
 
-    this.on('stop', function (done) {
+    this.on('stop', (done) => {
       this.log.debug('Received stop event, exiting.')
-      disconnectBrowsers()
+      this._close()
       done()
     })
 
@@ -332,9 +329,9 @@ class Server extends KarmaEventEmitter {
         emitRunCompleteIfAllBrowsersDone()
       })
 
-      this.on('run_complete', function (browsers, results) {
+      this.on('run_complete', (browsers, results) => {
         this.log.debug('Run complete, exiting.')
-        disconnectBrowsers(results.exitCode)
+        this._close(results.exitCode)
       })
 
       this.emit('run_start', singleRunBrowsers)
@@ -350,52 +347,13 @@ class Server extends KarmaEventEmitter {
       })
     }
 
-    const webServerCloseTimeout = 3000
-    const disconnectBrowsers = (code) => {
-      const sockets = socketServer.sockets.sockets
-
-      Object.keys(sockets).forEach((id) => {
-        const socket = sockets[id]
-        socket.removeAllListeners('disconnect')
-        if (!socket.disconnected) {
-          process.nextTick(socket.disconnect.bind(socket))
-        }
-      })
-
-      this.emitExitAsync(code).catch((err) => {
-        this.log.error('Error while calling exit event listeners\n' + err.stack || err)
-        return 1
-      }).then((code) => {
-        socketServer.sockets.removeAllListeners()
-        socketServer.close()
-
-        let removeAllListenersDone = false
-        const removeAllListeners = () => {
-          if (removeAllListenersDone) {
-            return
-          }
-          removeAllListenersDone = true
-          webServer.removeAllListeners()
-          processWrapper.removeAllListeners()
-          done(code || 0)
-        }
-
-        const closeTimeout = setTimeout(removeAllListeners, webServerCloseTimeout)
-
-        webServer.close(() => {
-          clearTimeout(closeTimeout)
-          removeAllListeners()
-        })
-      })
-    }
-
-    processWrapper.on('SIGINT', () => disconnectBrowsers(process.exitCode))
-    processWrapper.on('SIGTERM', disconnectBrowsers)
+    processWrapper.on('SIGINT', () => this._close())
+    processWrapper.on('SIGTERM', () => this._close())
 
     const reportError = (error) => {
-      process.emit('infrastructure_error', error)
-      disconnectBrowsers(1)
       this.log.error(error)
+      process.emit('infrastructure_error', error)
+      this._close(1)
     }
 
     processWrapper.on('unhandledRejection', (error) => {
@@ -429,6 +387,56 @@ class Server extends KarmaEventEmitter {
     child.unref()
   }
 
+  /**
+   * Cleanup all resources allocated by Karma and call the `done` callback
+   * with the result of the tests execution.
+   *
+   * @param [exitCode] - Optional exit code. If omitted will be computed by
+   * 'exit' event listeners.
+   */
+  _close (exitCode) {
+    const webServer = this._injector.get('webServer')
+    const socketServer = this._injector.get('socketServer')
+    const done = this._injector.get('done')
+
+    const webServerCloseTimeout = 3000
+    const sockets = socketServer.sockets.sockets
+
+    Object.keys(sockets).forEach((id) => {
+      const socket = sockets[id]
+      socket.removeAllListeners('disconnect')
+      if (!socket.disconnected) {
+        process.nextTick(socket.disconnect.bind(socket))
+      }
+    })
+
+    this.emitExitAsync(exitCode).catch((err) => {
+      this.log.error('Error while calling exit event listeners\n' + err.stack || err)
+      return 1
+    }).then((code) => {
+      socketServer.sockets.removeAllListeners()
+      socketServer.close()
+
+      let removeAllListenersDone = false
+      const removeAllListeners = () => {
+        if (removeAllListenersDone) {
+          return
+        }
+        removeAllListenersDone = true
+        webServer.removeAllListeners()
+        processWrapper.removeAllListeners()
+        done(code || 0)
+      }
+
+      const closeTimeout = setTimeout(removeAllListeners, webServerCloseTimeout)
+
+      webServer.close(() => {
+        clearTimeout(closeTimeout)
+        removeAllListeners()
+      })
+    })
+  }
+
   stop () {
     return this.emitAsync('stop')
   }
diff --git a/test/unit/server.spec.js b/test/unit/server.spec.js
index 01121213e..6523a709d 100644
--- a/test/unit/server.spec.js
+++ b/test/unit/server.spec.js
@@ -15,11 +15,11 @@ describe('server', () => {
   let mockSocketServer
   let mockBoundServer
   let mockExecutor
-  let doneSpy
+  let doneStub
   let logErrorSpy
   let server = mockConfig = browserCollection = webServerOnError = null
   let fileListOnResolve = fileListOnReject = mockLauncher = null
-  let mockFileList = mockWebServer = mockSocketServer = mockExecutor = doneSpy = null
+  let mockFileList = mockWebServer = mockSocketServer = mockExecutor = doneStub = null
   const mockSocketEventListeners = new Map()
 
   // Use regular function not arrow so 'this' is mocha 'this'.
@@ -27,13 +27,11 @@ describe('server', () => {
     // The first call to new Server() loads plugins and it can take >2000ms.
     this.timeout(4000)
     browserCollection = new BrowserCollection()
-    doneSpy = sinon.spy()
+    doneStub = sinon.stub()
     logErrorSpy = sinon.spy(logger.create('karma-server'), 'error')
 
     fileListOnResolve = fileListOnReject = null
 
-    doneSpy = sinon.spy()
-
     mockConfig = {
       frameworks: [],
       port: 9876,
@@ -49,7 +47,7 @@ describe('server', () => {
       browserNoActivityTimeout: 0
     }
 
-    server = new Server(mockConfig, doneSpy)
+    server = new Server(mockConfig, doneStub)
 
     sinon.stub(server._injector, 'invoke').returns([])
 
@@ -120,10 +118,10 @@ describe('server', () => {
       close: sinon.spy((callback) => callback && callback())
     }
 
-    sinon
-      .stub(server._injector, 'get')
-      .withArgs('webServer').returns(mockWebServer)
-      .withArgs('socketServer').returns(mockSocketServer)
+    const injectorStub = sinon.stub(server._injector, 'get')
+    injectorStub.withArgs('socketServer').returns(mockSocketServer)
+    injectorStub.withArgs('webServer').returns(mockWebServer)
+    injectorStub.callThrough()
 
     webServerOnError = null
   })
@@ -185,7 +183,7 @@ describe('server', () => {
     })
 
     it('should start the web server after all files have been preprocessed successfully', async () => {
-      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneSpy)
+      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
       expect(mockFileList.refresh).to.have.been.called
       expect(fileListOnResolve).not.to.be.null
@@ -199,7 +197,7 @@ describe('server', () => {
     })
 
     it('should start the web server after all files have been preprocessed with an error', async () => {
-      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneSpy)
+      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
       expect(mockFileList.refresh).to.have.been.called
       expect(fileListOnReject).not.to.be.null
@@ -215,7 +213,7 @@ describe('server', () => {
     })
 
     it('should launch browsers after the web server has started', async () => {
-      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneSpy)
+      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
       expect(mockWebServer.listen).not.to.have.been.called
       expect(webServerOnError).not.to.be.null
@@ -227,7 +225,7 @@ describe('server', () => {
     })
 
     it('should emit a listening event once server begin accepting connections', async () => {
-      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneSpy)
+      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
       const listening = sinon.spy()
       server.on('listening', listening)
@@ -239,7 +237,7 @@ describe('server', () => {
     })
 
     it('should emit a browsers_ready event once all the browsers are captured', async () => {
-      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneSpy)
+      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
       const browsersReady = sinon.spy()
       server.on('browsers_ready', browsersReady)
@@ -254,7 +252,7 @@ describe('server', () => {
     })
 
     it('should emit a browser_register event for each browser added', async () => {
-      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneSpy)
+      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
       const browsersReady = sinon.spy()
       server.on('browsers_ready', browsersReady)
@@ -276,43 +274,28 @@ describe('server', () => {
         })
       }
 
-      it('1 on load errors', async () => {
-        mockProcess(process)
+      beforeEach(() => {
+        doneStub.callsFake((exitCode) => resolveExitCode(exitCode))
+      })
 
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+      it('1 on load errors', async () => {
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
         server.loadErrors.push(['TestError', 'Test'])
         fileListOnResolve()
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
-
         expect(await exitCode()).to.have.equal(1)
       })
 
       it('given on run_complete', async () => {
-        mockProcess(process)
-
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
         server.emit('run_complete', browserCollection, { exitCode: 15 })
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
         expect(await exitCode()).to.have.equal(15)
       })
 
       it('given on run_complete with exit event listener (15)', async () => {
-        mockProcess(process)
-
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
         // last non-zero exit code will be taken
         server.on('exit', (done) => {
@@ -328,18 +311,11 @@ describe('server', () => {
         // Provided run_complete exitCode will be overridden by exit listeners
         server.emit('run_complete', browserCollection, { exitCode: 5 })
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
         expect(await exitCode()).to.have.equal(15)
       })
 
       it('given on run_complete with exit event listener (0)', async () => {
-        mockProcess(process)
-
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
         // exit listeners can't set exit code back to 0
         server.on('exit', (done) => {
@@ -348,18 +324,11 @@ describe('server', () => {
 
         server.emit('run_complete', browserCollection, { exitCode: 15 })
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
         expect(await exitCode()).to.have.equal(15)
       })
 
       it('1 on run_complete with exit event listener throws', async () => {
-        mockProcess(process)
-
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
         server.on('exit', (done) => {
           throw new Error('async error from exit event listener')
@@ -367,18 +336,11 @@ describe('server', () => {
 
         server.emit('run_complete', browserCollection, { exitCode: 0 })
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
         expect(await exitCode()).to.have.equal(1)
       })
 
       it('1 on run_complete with exit event listener rejects', async () => {
-        mockProcess(process)
-
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
         function onExit (done) {
           // Need to remove listener to prevent endless loop via unhandledRejection handler
@@ -390,71 +352,40 @@ describe('server', () => {
 
         server.emit('run_complete', browserCollection, { exitCode: 0 })
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
         expect(await exitCode()).to.have.equal(1)
       })
 
       it('0 on server stop', async () => {
-        mockProcess(process)
-
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
         server.stop()
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
         expect(await exitCode()).to.have.equal(0)
       })
 
       it('1 on browser_process_failure (singleRunBrowserNotCaptured)', async () => {
-        mockProcess(process)
-
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
         server.emit('browser_process_failure', { id: 'fake' })
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
         expect(await exitCode()).to.have.equal(1)
       })
 
       it('0 on browser_complete_with_no_more_retries', async () => {
-        mockProcess(process)
-
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
         server.emit('browser_complete_with_no_more_retries', { id: 'fake', remove: () => {} })
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
         expect(await exitCode()).to.have.equal(0)
       })
 
       it('1 on browser_complete_with_no_more_retries with config.failOnEmptyTestSuite', async () => {
-        mockProcess(process)
-
         mockConfig.failOnEmptyTestSuite = true
 
-        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, (exitCode) => {
-          resolveExitCode(exitCode)
-        })
+        await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
         server.emit('browser_complete_with_no_more_retries', { id: 'fake', remove: () => {} })
 
-        function mockProcess (process) {
-          sinon.stub(process, 'kill').callsFake((pid, ev) => process.emit(ev))
-        }
         expect(await exitCode()).to.have.equal(1)
       })
     })
@@ -465,7 +396,7 @@ describe('server', () => {
 
     beforeEach(async () => {
       browserCollection = new BrowserCollection(server)
-      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneSpy)
+      await server._start(mockConfig, mockLauncher, null, mockFileList, browserCollection, mockExecutor, doneStub)
 
       mockBrowserSocket = {
         id: 'browser-socket-id',