raise an error if Capybara is stuck in time

lib/capybara.rb

@@ -4,6 +4,7 @@
 module Capybara
   class CapybaraError < StandardError; end
   class DriverNotFoundError < CapybaraError; end
+  class FrozenInTime < CapybaraError; end
   class ElementNotFound < CapybaraError; end
   class ExpectationNotMet < ElementNotFound; end
   class FileNotFound < CapybaraError; end

lib/capybara/node/base.rb

@@ -49,6 +49,7 @@ def wait_until(seconds=Capybara.default_wait_time)
           raise e unless (driver.respond_to?(:invalid_element_errors) and driver.invalid_element_errors.include?(e.class)) or e.is_a?(Capybara::ElementNotFound)
           raise e if (Time.now - start_time) >= seconds
           sleep(0.05)
+          raise Capybara::FrozenInTime, "time appears to be frozen, Capybara does not work with libraries which freeze time, consider using time travelling instead" if Time.now == start_time
           reload if Capybara.automatic_reload
           retry
         end

lib/capybara/spec/session/javascript.rb

@@ -123,6 +123,15 @@
         @session.click_link('Click me')
         @session.find(:css, "a#has-been-clicked").text.should include('Has been clicked')
       end
+
+      context "with frozen time" do
+        it "raises an error suggesting that Capybara is stuck in time" do
+          @session.visit('/with_js')
+          now = Time.now
+          Time.stub(:now).and_return(now)
+          expect { @session.find('//isnotthere') }.to raise_error(Capybara::FrozenInTime)
+        end
+      end
     end
 
     describe '#wait_until' do