test('mapJoin should work with only two arguments', () => {
    var result = objectUtils.mapJoin({ a: 1, b: 2 }, (v, k) => k + '-' + v);
    expect(result, 'a-1b-2');
});
test('mapJoin should work', () => {
    var result = objectUtils.mapJoin({ a: 1, b: 2 }, '_', (v, k) => k + '-' + v);
    expect(result, 'a-1_b-2');
});