Rspec with Capybara sometimes not pass tests - ruby-on-rails

Question

I have problem with testing Rails Application. My tests generally work perfectly. But sometimes tests will fail when I type some features test for modal bootstrap window, or notify with success/error [js]. How can I resolve this problem ?
I'm using Rspec, Capybara, Rails4.2, PhantomJs, Poltergeist as JS driver. Tests is running locally and in Wercker. In test mode, every bootstrap animation is disabled. What perhaps I do wrong ?
Test:
scenario 'return deutsch default title' do
find('.f-edit-item', match: :first).click
find('a', :text => 'Lang').click
find('a', :text => t('menu.languages.de')).click
find('.f-reset-button', match: :first).click
expect(page).to have_field('menu_item[title]', with: 'Exhibitions_de')
end
Output:
Objects Restore Language restore title translations exist for deutsch translation return deutsch default title
Failure/Error: expect(page).to have_field('object_item[title]', with: 'Exhibitions_de')
expected to find field "object_item[title]" with value "Exhibitions_de" but there were no matches. Also found "", "", which matched the selector but not all filters.
When I click manually, everything is working. When I run this test, sometimes passed, sometimes not. Form is in bootstrap modal. Curiosity: When I add save_and_open_page before find('.f-reset-button', match: :first).click test is passed always(5x in a row)

Answer 1

Because the tests are to do with a Bootstrap modal, my guess is that the test is searching the page for the matching elements, BEFORE the modal has loaded in the DOM.
Edit: As #TomWalpole pointed out, it should be enough to override Capybara's max wait time like so:
expect(page).to have_field('menu_item[title]', with: 'Exhibitions_de', wait: 1.0)
But if you are loading the contents of your modal via AJAX, you may need to force a wait for AJAX to complete the expect line. Here is a good guide on how to do this.
Specifically you need:
# spec/support/wait_for_ajax.rb
module WaitForAjax
def wait_for_ajax
Timeout.timeout(Capybara.default_wait_time) do
loop until finished_all_ajax_requests?
end
end
def finished_all_ajax_requests?
page.evaluate_script('jQuery.active').zero?
end
end
RSpec.configure do |config|
config.include WaitForAjax, type: :feature
end
And then your test would become:
scenario 'return deutsch default title' do
find('.f-edit-item', match: :first).click
find('a', :text => 'Lang').click
find('a', :text => t('menu.languages.de')).click
find('.f-reset-button', match: :first).click
wait_for_ajax
expect(page).to have_field('menu_item[title]', with: 'Exhibitions_de')
end