describe('takeWhile', function() it('produces an error if its parent errors', function() local observable = Rx.Observable.fromValue(''):map(function(x) return x() end) expect(observable.subscribe).to.fail() expect(observable:takeWhile(function() end).subscribe).to.fail() end) it('uses the identity function if no predicate is specified', function() local observable = Rx.Observable.fromTable({true, true, false}):takeWhile() expect(observable).to.produce(true, true) end) it('stops producing values once the predicate returns false', function() local function isEven(x) return x % 2 == 0 end local observable = Rx.Observable.fromTable({2, 3, 4}, ipairs):takeWhile(isEven) expect(observable).to.produce(2) end) it('produces no values if the predicate never returns true', function() local function isEven(x) return x % 2 == 0 end local observable = Rx.Observable.fromTable({1, 3, 5}):takeWhile(isEven) expect(observable).to.produce({}) end) end)