Add none helper

[magistrula]

Given the following test...

it('can clear the Roster', function() {
  RosterPageObject.clearRoster();

  // expect Roster to be in its initial state
  expect(RosterPageObject.rosterNames().count).to.equal(0);
  expect(RosterPageObject.nameInputValue).to.equal('');
  expect(RosterPageObject.isClearButtonVisible).to.be.false;
});

It may be helpful for the PageObject to define what it means for the Roster to be "empty" so that the tests don't have to check each individual criterion, and so that these criteria do not need to be repeated every time we need to check whether the roster is empty. A none helper would be useful in this case:

const RosterPageObject = create({
  rosterNames: collection({
    itemScope: '.roster-name'
  }),
  nameInputValue: value('.name-input'),
  isClearButtonVisible: isVisible('.clear-button'),

  isRosterBlank: none('rosterNames', 'nameInputValue', 'isClearButtonVisible')
});

This would allow the test above to be rewritten as follows:

it('can clear the Roster', function() {
  RosterPageObject.clearRoster();

  expect(RosterPageObject.isRosterBlank).to.be.true;
});

[ro0gr]

Closing, since it can be achieved with getters. see #300 (comment)