“require 'capybara/rails'”给出“未初始化的常量 Rack::Builder”

Question

我一直在我的应用程序中使用 cucumber，这是一个在 ruby​​ 1.8.6 中运行的 rails 2.2.2 应用程序（现在不能升级）。黄瓜很好，现在我正在尝试使用水豚。我已经安装了capybara (1.1.1) gem 并将require 'capybara/rails' 行放在我的features/support/env.rb file 中。

现在，当我运行 cucumber 时，出现此错误：

Using the default profile...
uninitialized constant Rack::Builder (NameError)
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:445:in `load_missing_constant'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:77:in `const_missing'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/capybara-1.1.1/lib/capybara/rails.rb:4
/home/max/.rvm/rubies/ruby-1.8.6-p420/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
/home/max/.rvm/rubies/ruby-1.8.6-p420/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `require'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/activesupport-2.2.2/lib/active_support/dependencies.rb:155:in `require'
/home/max/work/charanga/elearn_container/elearn/features/support/env.rb:10
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/rb_support/rb_language.rb:143:in `load'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/rb_support/rb_language.rb:143:in `load_code_file'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/runtime/support_code.rb:171:in `load_file'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/runtime/support_code.rb:83:in `load_files!'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/runtime/support_code.rb:82:in `each'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/runtime/support_code.rb:82:in `load_files!'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/runtime.rb:137:in `load_step_definitions'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/runtime.rb:39:in `run!'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/cli/main.rb:43:in `execute!'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/../lib/cucumber/cli/main.rb:20:in `execute'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/cucumber-1.1.1/bin/cucumber:14
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/bin/cucumber:19:in `load'
/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/bin/cucumber:19

这是错误文件：

#/home/max/.rvm/gems/ruby-1.8.6-p420@elearning-resource/gems/capybara-1.1.1/lib/capybara/rails.rb
require 'capybara'
require 'capybara/dsl'

Capybara.app = Rack::Builder.new do
  map "/" do
    if Rails.version.to_f >= 3.0
      run Rails.application  
    else # Rails 2
      use Rails::Rack::Static
      run ActionController::Dispatcher.new
    end
  end
end.to_app

Capybara.asset_root = Rails.root.join('public')
Capybara.save_and_open_page_path = Rails.root.join('tmp/capybara')

因此，第 4 行正在使用 Rack::Builder.new 行创建错误。但为什么？有任何想法吗？我已经安装了 Rack gem。

谢谢，马克斯

Answer 1

尝试在features/support/env.rb 中的require 'capybara/rails' 之前添加require 'rack/builder'。低于 2.3 的 Rails 版本不会在内部使用 Rack，因此不会像 capybara 假设的那样加载 Rack::Builder。

Answer 2

您是否使用了 cucumber-rails gem？

https://github.com/jnicklas/capybara 说，要么使用 gem，要么，如果你没有使用 rails，把这两行都放进去：

require 'capybara/cucumber'
Capybara.app = MyRackApp

Answer 3

试试这个

  gem install rack

  require 'rack' # in features/support/env.rb before every require

Rack::Builder 在机架库中定义。