Ruby on rails 在rails 3中运行时，object.keys不是函数

我试图在rails 3环境中运行一些cumber文件。下面是相关文件的列表

gemfile:-

group :test do
  # Pretty printed test output
  gem 'turn', '< 0.8.3'
  gem 'capybara'#,'1.1.2'
  gem 'launchy','2.0.5'
  gem 'cucumber-rails','1.2.1'
  gem 'cucumber','1.1.4'
  gem 'rspec-rails','2.8.1'
  gem 'rspec-cells','0.1.2'
  gem 'email_spec' 
  gem 'machinist', '>= 2.0.0.beta2'
  gem "factory_girl_rails"
  gem "guard-rspec"
  gem "minitest"
  gem 'headless'
  gem 'minitest-rails'
  gem 'minitest-rails-capybara'
  # gem 'minitest-rails',:git => "git://github.com/rawongithub/minitest-rails.git"  
  # gem 'capybara_minitest_spec'
  gem 'rails_sql_views', :git => 'https://github.com/mremolt/rails_sql_views.git'
 end

当我运行rake ruby-S bundle exec cumber-p default时——需要特性/运行_文件/登录。特性：27

我得到这个错误

 And I fill in "user[email]" with "admin@newadmin.com"               # features/step_definitions/web_steps.rb:109
      Object.keys is not a function (Selenium::WebDriver::Error::UnknownError)
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:8169:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:388:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:390:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:8205:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:388:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:390:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:8206:in `injectAndExecuteScript'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:8211:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/command_processor.js:263:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/command_processor.js:10222:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/command_processor.js:10227:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/command_processor.js:10167:in `unknown'
      ./features/step_definitions/web_steps.rb:110:in `/^I fill in "([^"]*)" with "([^"]*)"$/'

---

我仍然无法找出原因。此外，我没有做任何重大更改。

错误发生在web_steps.rb中。你能把引起错误的代码贴在哪里吗？这不是新的吗，Selenium在幕后使用的是哪种浏览器？它的firefox 3.6.9…我仍在努力找出问题所在。

 And I fill in "user[email]" with "admin@newadmin.com"               # features/step_definitions/web_steps.rb:109
      Object.keys is not a function (Selenium::WebDriver::Error::UnknownError)
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:8169:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:388:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:390:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:8205:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:388:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:390:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:8206:in `injectAndExecuteScript'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/driver_component.js:8211:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/command_processor.js:263:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/command_processor.js:10222:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/command_processor.js:10227:in `unknown'
      [remote server] file:///tmp/webdriver-profile20121220-28325-14ft8a7/extensions/fxdriver@googlecode.com/components/command_processor.js:10167:in `unknown'
      ./features/step_definitions/web_steps.rb:110:in `/^I fill in "([^"]*)" with "([^"]*)"$/'