Rails - Rspec/Capybara reporting fail unless sleep added - ruby-on-rails

Question

I have a page where a logged in user can set a favourite item by submitting an ajax request which calls the following controller method:
def create
item = Item.find(params[:id])
if params[:commit] == 'save'
item.unhide!(current_user) if item.is_hidden_by?(current_user)
item.save_as_favourite_for!(current_user)
else
item.remove_as_favourite!(current_user) if item.is_favourite_of?(current_user)
item.hide_for!(current_user)
end
respond_to do |format|
format.html { redirect_back_or items_path }
format.js {render "create", locals: {item: item, index: params[:index].to_i || nil, page:params[:page]} }
end
end
This all works as expected, but I have a request spec which is defined to test the front end functionality:
describe "saving items", js: true do
let!(:current_user) {FactoryGirl.create(:user, email: "user#example.com", active: true)}
let!(:favourite_item) {FactoryGirl.create(:item)}
before { sign_in current_user }
describe "when saving a item" do
it "should save the user against the item" do
expect do
click_button "save"
# sleep(0.02)
end.to change(favourite_item.savers, :count).by(1)
end
end
end
Notice the commented out sleep(0.02) statement. If this statement is commented out, the test (almost) always fails, however if I include the call, and immediately end the console interrupt, then the test passes every time. (any more time delay and it fails).
Is there a better way to write this test without the workaround and why might it be failing without the delay?

Answer 1

You can set a wait time using the dsl.
using_wait_time 3 do
expect do
click_button "save"
end.to change(favourite_item.savers, :count).by(1)
end
http://rubydoc.info/github/jnicklas/capybara/Capybara.using_wait_time
The default wait time is 2 seconds for JS tests if you use an Rspec matcher, which you are not for this test.
It'll probably also pass if you remove js: true unless you really need the js driver for the test.