Class: Capybara::Lockstep::Client

Inherits:
Object
  • Object
show all
Includes:
Logging, PageAccess
Defined in:
lib/capybara-lockstep/client.rb

Constant Summary collapse

ERROR_SNIPPET_MISSING = 
'Cannot synchronize: capybara-lockstep JavaScript snippet is missing'
ERROR_PAGE_MISSING = 
'Cannot synchronize with empty page'
ERROR_ALERT_OPEN = 
'Cannot synchronize while an alert is open'
ERROR_WINDOW_CLOSED = 
'Cannot synchronize with closed window'
ERROR_NAVIGATED_AWAY = 
"Browser navigated away while synchronizing"
SYNCHRONIZED_IVAR = 
:@lockstep_synchronized_client

Instance Method Summary collapse

Methods included from PageAccess

#alert_present?, #javascript_driver?, #page

Methods included from Logging

#log

Instance Method Details

#synchronize ⇒ Object 



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# File 'lib/capybara-lockstep/client.rb', line 36

def synchronize
  # If synchronization fails below we consider us unsynchronized after.
  self.synchronized = false

  # Running the synchronization script while an alert is open would close the alert,
  # most likely causing subsequent expectations to fail.
  if alert_present?
    log ERROR_ALERT_OPEN
    # Don't raise an error, this will happen in an innocent test.
    # We will retry on the next Capybara synchronize call.
    return
  end

  start_time = Util.current_seconds

  begin
    Util.with_max_wait_time(timeout) do
      message_from_js = evaluate_async_script(<<~JS)
        let done = arguments[0]
        let synchronize = () => {
          if (window.CapybaraLockstep) {
            CapybaraLockstep.synchronize(done)
          } else {
            done(#{ERROR_SNIPPET_MISSING.to_json})
          }
        }
        const emptyDataURL = /^data:[^,]*,?$/
        if (emptyDataURL.test(location.href) || location.protocol === 'about:') {
          done(#{ERROR_PAGE_MISSING.to_json})
        } else if (document.readyState === 'complete') {
          // WebDriver always waits for the `load` event after a visit(),
          // unless a different page load strategy was configured.
          synchronize()
        } else {
          window.addEventListener('load', synchronize)
        }
      JS

      case message_from_js
      when ERROR_PAGE_MISSING
        log(message_from_js)
      when ERROR_SNIPPET_MISSING
        log(message_from_js)
      else
        log message_from_js
        end_time = Util.current_seconds
        ms_elapsed = ((end_time.to_f - start_time) * 1000).round
        log "Synchronized client successfully [#{ms_elapsed} ms]"
        self.synchronized = true
      end
    end
  rescue ::Selenium::WebDriver::Error::ScriptTimeoutError
    timeout_message = "Could not synchronize client within #{timeout} seconds"
    log timeout_message
    if timeout_with == :error
      raise Timeout, timeout_message
    else
      # Don't raise an error, this may happen if the server is slow to respond.
      # We will retry on the next Capybara synchronize call.
    end
  rescue ::Selenium::WebDriver::Error::UnexpectedAlertOpenError
    log ERROR_ALERT_OPEN
    # Don't raise an error, this will happen in an innocent test where a click opens an alert.
    # We will retry on the next Capybara synchronize call.
  rescue ::Selenium::WebDriver::Error::NoSuchWindowError
    log ERROR_WINDOW_CLOSED
    # Don't raise an error, this will happen in an innocent test where a click closes a window.
    # We will retry on the next Capybara synchronize call.
  rescue ::Selenium::WebDriver::Error::JavascriptError => e
    # When the URL changes while a script is running, my current selenium-webdriver
    # raises a Selenium::WebDriver::Error::JavascriptError with the message:
    # "javascript error: document unloaded while waiting for result".
    # We will retry on the next Capybara synchronize call, by then we should see
    # the new page.
    if e.message.include?('unload')
      log ERROR_NAVIGATED_AWAY
    else
      unhandled_synchronize_error(e)
    end
  rescue StandardError => e
    unhandled_synchronize_error(e)
  end
end

#synchronized=(value) ⇒ Object 



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# File 'lib/capybara-lockstep/client.rb', line 32

def synchronized=(value)
  page.instance_variable_set(SYNCHRONIZED_IVAR, value)
end

#synchronized? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/capybara-lockstep/client.rb', line 15

def synchronized?
  # The synchronized flag is per-session (page == Capybara.current_session).
  # This enables tests that use more than one browser, e.g. to test multi-user interaction:
  # https://makandracards.com/makandra/474480-how-to-make-a-cucumber-test-work-with-multiple-browser-sessions
  #
  # Ideally the synchronized flag would also be per-tab, per-frame and per-document.
  # We haven't found a way to patch this into Capybara, as there does not seem to be
  # a persistent object representing a document. Capybara::Node::Document just seems to
  # be a proxy accessing whatever is the current document. The way we work around this
  # is that we synchronize before switching tabs or frames.
  value = page.instance_variable_get(SYNCHRONIZED_IVAR)

  # We consider a new Capybara session to be synchronized.
  # This will be set to false after our first visit().
  value.nil? ? true : value
end