Karma Babel Preprocessor cannot parse ES6 lambda syntax () -> {};

file.js

window.temp = "world";

let test = "hello";
window.test = test;

var { one, two } = { one: 1, two: 2 };
window.one = one;
window.two = two;

window.foo = function (bar = "bar") {
	return bar;
};

//window.bar = () -> "foo"; // breaks

karma.conf.js

// Karma configuration
// Generated on Sat Aug 06 2016 23:33:56 GMT-0700 (Pacific Daylight Time)

module.exports = function(config) {
	config.set({
		// base path that will be used to resolve all patterns (eg. files, exclude)
		basePath: '',
		
		plugins: [ "karma-jasmine", "karma-phantomjs-launcher", "karma-babel-preprocessor" ],
		
		// frameworks to use
		// available frameworks: https://npmjs.org/browse/keyword/karma-adapter
		frameworks: ['jasmine'],
		
		
		// list of files / patterns to load in the browser
		files: [
			'file.js',
			'test.js'
		],
		
		
		// list of files to exclude
		exclude: [
		],
		
		
		// preprocess matching files before serving them to the browser
		// available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
		preprocessors: {
			'*.js': ['babel']
		},
		
		babelPreprocessor: {
			options: {
				presets: ['es2015'],
				sourceMap: 'inline'
			}
		},
		
		
		// test results reporter to use
		// possible values: 'dots', 'progress'
		// available reporters: https://npmjs.org/browse/keyword/karma-reporter
		reporters: ['progress'],
		
		
		// web server port
		port: 9876,
		
		
		// enable / disable colors in the output (reporters and logs)
		colors: true,
		
		
		// level of logging
		// possible values: config.LOG_DISABLE || config.LOG_ERROR || config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
		logLevel: config.LOG_INFO,
		
		
		// enable / disable watching file and executing tests whenever any file changes
		autoWatch: false,
		
		
		// start these browsers
		// available browser launchers: https://npmjs.org/browse/keyword/karma-launcher
		browsers: ['PhantomJS'],
		
		
		// Continuous Integration mode
		// if true, Karma captures browsers, runs the tests and exits
		singleRun: true,
		
		// Concurrency level
		// how many browser should be started simultaneously
		concurrency: Infinity
	});
};

package.json

{
  "name": "karma-es6",
  "version": "1.0.0",
  "scripts": {
    "test": "node ./node_modules/karma/bin/karma start"
  },
  "devDependencies": {
    "babel": "^6.5.2",
    "babel-preset-es2015": "^6.13.2",
    "jasmine-core": "^2.4.1",
    "karma": "^1.1.2",
    "karma-babel-preprocessor": "^6.0.1",
    "karma-jasmine": "^1.0.2",
    "karma-phantomjs-launcher": "^1.0.1"
  }
}

test.js

describe("Jasmine", function () {
	it("runs es5 source code", function () {
		expect(window.temp).toBe("world");
	});
	
	it("runs es6-compiled source code with let", function () {
		expect(window.test).toBe("hello");
	});
	
	it("runs es6-compiled source code with expansion", function () {
		expect(window.one).toBe(1);
		expect(window.two).toBe(2);
	});
	
	it("runs es6-compiled source code with default parameters", function () {
		expect(window.foo()).toBe("bar");
	});
	
	it("runs es6-compiled source code with lambda notation", function () {
		expect(window.bar()).toBe("foo");
	});
	
	it("runs es6-compiled tests with let", function () {
		let value = window.test;
		expect(value).toBe("hello");
	});
	
	it("runs es6-compiled tests with expansion", function () {
		var { one, two } = { one: 1, two: 2 };
		expect(one).toBe(1);
		expect(two).toBe(2);
	});
	
	it("runs es6-compiled tests with default parameters", function () {
		var foo = function (bar = "bar") { return bar; };
		expect(foo()).toBe("bar");
	});
	
	it("runs es6-compiled tests with lambda notation", function () {
		//var bar = () -> "foo"; // breaks
		expect(bar()).toBe("foo");
	});
});