Attempt at a custom Jasmine matcher for ES6 Map equality testing, using the spread operator

gistfile1.js

import cfg from '../lib/config-parser';

var customMatchers = {
    toEqualMap: (util, customEqualityTesters) => {
        return {
            compare: (actual, expected) => {
                var result = {};
                result.pass = util.equals([...actual], [...expected], customEqualityTesters);

                if(!result.pass) {
                    result.message = `Expected map:\n${[...actual]} to equal\n${[...expected]}`;
                }

                return result;
            }
        };
    }
};

describe("Config parser", () => {
    beforeEach(() => {
        jasmine.addMatchers(customMatchers);
    });

    it("should parse an empty config", () => {
        var result = cfg.parse('');
        var expected = new Map([]);

        expect(result).toEqualMap(expected);
    });

    it("should parse a config with no sections", () => {
        var result = cfg.parse(`key1 = value1
key2 = value2
key with spaces = value with spaces
akey = avalue`);

        var expected = new Map([
            ['key1', 'value1'],
            ['key2', 'value2'],
            ['key with spaces', 'value with spaces'],
            ['akey', 'avalue']
        ]);

        expect(result).toEqualMap(expected);
    });
});

Any feedback welcome as I am not sure if this is a good way to do this or not