Angular2 + Karma (very simple setup)

index.spec.ts

import 'core-js/es6';
import 'core-js/es7/reflect';
import 'reflect-metadata';

import 'zone.js/dist/zone';
import 'zone.js/dist/long-stack-trace-zone';
import 'zone.js/dist/proxy';
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 { TestBed } from '@angular/core/testing';
import { BrowserDynamicTestingModule, platformBrowserDynamicTesting } from '@angular/platform-browser-dynamic/testing';

TestBed.initTestEnvironment(BrowserDynamicTestingModule, platformBrowserDynamicTesting());

karma.conf.js

module.exports = function (config) {
  var _config = {

    frameworks: [ 'jasmine', 'karma-typescript' ],

    files: [
      { pattern: 'index.spec.ts' },
      { pattern: 'src/**/*.+(ts|html)' }
    ],

    preprocessors: {
      "**/*.ts": [ 'karma-typescript' ]
    },

    karmaTypescriptConfig: {
      tsconfig: './tsconfig.test.json'
    },

    reporters: [ 'progress', 'karma-typescript' ],
    port: 9876,
    colors: true,
    logLevel: config.LOG_INFO,
    autoWatch: false,
    browsers: [ 'Chrome' ],
    singleRun: true
  };

  config.set(_config);
};

tsconfig.test.json

{
  "compileOnSave": false,
  "compilerOptions": {
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "sourceMap": true,
    "target": "es5",
    "module": "commonjs",
    "lib": ["dom", "es6"]
  },
  "exclude": [
    "node_modules"
  ]
}