Nicer warnings when option not found for select

lib/capybara.rb

@@ -7,6 +7,7 @@ module Capybara
   class CapybaraError < StandardError; end
   class DriverNotFoundError < CapybaraError; end
   class ElementNotFound < CapybaraError; end
+  class OptionNotFound < ElementNotFound; end
   class NotSupportedByDriverError < CapybaraError; end
   class TimeoutError < CapybaraError; end
   class InfiniteRedirectError < TimeoutError; end

lib/capybara/driver/celerity_driver.rb

@@ -19,6 +19,9 @@ class Capybara::Driver::Celerity < Capybara::Driver::Base
 
     def select(option)
       node.select(option)
+    rescue
+      options = all(:xpath, "//option").map { |o| "'#{o.text}'" }.join(', ')
+      raise Capybara::OptionNotFound, "No such option '#{option}' in this select box. Available options: #{options}"
     end
 
     def click

lib/capybara/driver/rack_test_driver.rb

@@ -33,7 +33,12 @@ class Capybara::Driver::RackTest < Capybara::Driver::Base
 
     def select(option)
       node.xpath(".//option").each { |node| node.remove_attribute("selected") }
-      node.xpath(".//option[contains(.,'#{option}')]").first["selected"] = 'selected'
+      if option_node = node.xpath(".//option[contains(.,'#{option}')]").first
+        option_node["selected"] = 'selected'
+      else
+        options = node.xpath(".//option").map { |o| "'#{o.text}'" }.join(', ')
+        raise Capybara::OptionNotFound, "No such option '#{option}' in this select box. Available options: #{options}"
+      end
     end
 
     def click

lib/capybara/driver/selenium_driver.rb

@@ -29,6 +29,9 @@ class Capybara::Driver::Selenium < Capybara::Driver::Base
 
     def select(option)
       node.find_element(:xpath, ".//option[contains(.,'#{option}')]").select
+    rescue
+      options = node.find_elements(:xpath, "//option").map { |o| "'#{o.text}'" }.join(', ')
+      raise Capybara::OptionNotFound, "No such option '#{option}' in this select box. Available options: #{options}"
     end
 
     def click

spec/dsl/select_spec.rb

@@ -21,5 +21,11 @@ shared_examples_for "select" do
         running { @session.select('foo', :from => 'does not exist') }.should raise_error(Capybara::ElementNotFound)
       end
     end
+
+    context "with an option that doesn't exist" do
+      it "should raise an error" do
+        running { @session.select('Does not Exist', :from => 'form_locale') }.should raise_error(Capybara::OptionNotFound)
+      end
+    end
   end
 end