Angular 4 karma test configuration

test.ts

import 'babel-polyfill/dist/polyfill.js';
import 'zone.js/dist/zone.js';
import 'zone.js/dist/long-stack-trace-zone';
import 'zone.js/dist/proxy.js';
import 'zone.js/dist/sync-test';
import 'zone.js/dist/jasmine-patch';
import 'zone.js/dist/async-test';
import 'zone.js/dist/fake-async-test';

import { getTestBed } from '@angular/core/testing';
import {
    BrowserDynamicTestingModule,
    platformBrowserDynamicTesting
} from '@angular/platform-browser-dynamic/testing';

declare const __karma__: any;
declare const require: any;

__karma__.loaded = function () {};

getTestBed().initTestEnvironment(
    BrowserDynamicTestingModule,
    platformBrowserDynamicTesting()
);
const context = require.context('./', true, /\.spec\.ts$/);

context.keys().map(context);

__karma__.start();