es6 flatten test

flatten.test.js

import { flatten } from "./flatten";

test('flatten works', () => {

    expect(
        flatten(
            [1, 2, [3, 4, 5], 6, [7], 8, 9, 10]
        )
    ).toEqual(
        [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    );

});

test('flatten works with multiple levels of nested arrays', () => {

    expect(
        flatten(
            [1, 2, [3, 4, 5], 6, [7, [8, [9]], 10]]
        )
    ).toEqual(
        [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    );

});


test('flatten works with no nesting', () => {

    expect(
        flatten(
            [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
        )
    ).toEqual(
        [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    );

});