Succeed or sleep and try again (for Capybara js)

.Succeed or sleep (for capybara js)

 Succeed or sleep and try again (for Capybara js)

README.md

Succeed or sleep and try again (for Capybara js)

Using Capybara and Selenium in a rails system / feature spec, I get random errors sometimes on CI (rarely locally) which come from either a StaleElementReferenceError or also sometimes just a Capybara ElementNotFound error (often because I have failed to explicitly look for some change).

Sometimes I can work around this with enough expect...to have or expect...not_to have, but sometimes I just can't. It feels awful (and actually slows down everything) to put in random sleep amounts.

But, inspired by https://accidentaltechnologist.com/ruby-on-rails/fixing-staleelementreferenceerror-when-using-capybara/, how about only sleeping when it fails?

Here's my response to this:

Sample usage:

describe "something that is temperamental", js: true do
  visit "some/path"
  click_on "some button"
  succeed_or_sleep do
    expect(page).to have_content("some new content")
  end
end

Attached are the support file, and a spec for testing the support file

succeed_or_sleep_support.rb

# frozen_string_literal: true

RSpec.configure do |config|
  RSpec.shared_context "SucceedOrSleepSupport" do
    def succeed_or_sleep(time_to_sleep_if_it_fails = 1)
      yield
    rescue Selenium::WebDriver::Error::StaleElementReferenceError, Capybara::CapybaraError
      if @succeed_or_sleep_already_run
        raise
      else
        @succeed_or_sleep_already_run = true
        sleep time_to_sleep_if_it_fails
        retry
      end
    end
  end

  config.include_context "SucceedOrSleepSupport", js: true
end

succeed_or_sleep_support_spec.rb

# frozen_string_literal: true

require "rails_helper"

describe "SucceedOrSleepSupport", type: :feature, js: true do
  it "rescues and retries" do
    already_run = false
    succeed_or_sleep(0) do
      next if already_run
      already_run = true
      raise Selenium::WebDriver::Error::StaleElementReferenceError
    end
  end

  # rubocop:disable RSpec/InstanceVariable
  it "rescues and retries only once" do
    @iteration = 0
    succeed_or_sleep(0) do
      @iteration += 1
      case @iteration
      when 1
        raise Selenium::WebDriver::Error::StaleElementReferenceError
      when 2
        raise Selenium::WebDriver::Error::StaleElementReferenceError
      else
        flunk "expected it to only retry once, but it has run #{iteration - 1} times"
      end
    end
  rescue Selenium::WebDriver::Error::StaleElementReferenceError
    expect(@iteration).to eq(2)
    # in which case this is an expected error
  end
  # rubocop:enable RSpec/InstanceVariable
end