frontend/test-mocha/common/datetime/seconds_to_duration_test.js

import { assert } from 'chai';

import secondsToDuration from '../../../js/common/datetime/seconds_to_duration.js';

describe('secondsToDuration', () => {
  it('works', () => {
    assert.strictEqual(secondsToDuration(0), null);
    assert.strictEqual(secondsToDuration(65), '1:05');
    assert.strictEqual(secondsToDuration(3665), '1:01:05');
    assert.strictEqual(secondsToDuration(39665), '11:01:05');
  });
});