Immutable.js can create nested groups.js

var Immutable = require('immutable');

describe('Immutable', function () {
	it('can create nested groups', function () {
		var items = [
			{key1: 'a', key2: 'A'},
			{key1: 'a', key2: 'A'},
			{key1: 'a', key2: 'B'},
			{key1: 'b', key2: 'A'},
			{key1: 'b', key2: 'B'}
		];
		var result = Immutable.List(items)
		.groupBy(function (item) {
			return item.key1;
		})
		.map(function (items) {
			return items.groupBy(function (item) {
				return item.key2;
			});
		})
		.toJS();
		expect(result.a.A).toContain(items[0]);
		expect(result.a.A).toContain(items[1]);
		expect(result.a.B).toContain(items[2]);
		expect(result.b.A).toContain(items[3]);
		expect(result.b.B).toContain(items[4]);
	});
});