describe('count', function()
  it('passes through errors', function()
    local observable = Rx.Observable.create(function(observer) observer:onError() end)
    expect(observable.subscribe).to.fail()
    expect(observable:count().subscribe).to.fail()
  end)

  it('produces a single value representing the number of elements produced by the source', function()
    local observable = Rx.Observable.fromRange(5):count()
    expect(observable).to.produce(5)
  end)

  it('uses the predicate to filter for values if it is specified', function()
    local observable = Rx.Observable.fromRange(5):count(function(x) return x > 3 end)
    expect(observable).to.produce(2)
  end)
end)