我正在关注http://ruby.railstutorial.org/上的教程，现在我无法启动服务器。在我的 gemfile 中，我使用的是 ruby 2.0.0 和 rails 4.0.0.rc1 - 然后我尝试改回 ruby 1.9.3 和 rails 3.2.13 - 仍然无法正常工作
这是终端告诉我的：
/config/environments/development.rb:1:in `<top (required)>': uninitialized constant FourTest (NameError)
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/engine.rb:591:in `block (2 levels) in <class:Engine>'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/engine.rb:590:in `each'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/engine.rb:590:in `block in <class:Engine>'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/initializable.rb:30:in `instance_exec'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/initializable.rb:30:in `run'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/initializable.rb:55:in `block in run_initializers'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:150:in `block in tsort_each'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:183:in `block (2 levels) in each_strongly_connected_component'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:210:in `block (2 levels) in each_strongly_connected_component_from'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:219:in `each_strongly_connected_component_from'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:209:in `block in each_strongly_connected_component_from'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/initializable.rb:44:in `each'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/initializable.rb:44:in `tsort_each_child'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:203:in `each_strongly_connected_component_from'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:182:in `block in each_strongly_connected_component'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:180:in `each'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:180:in `each_strongly_connected_component'
from /Users/markustorok/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/tsort.rb:148:in `tsort_each'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/initializable.rb:54:in `run_initializers'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/application.rb:214:in `initialize!'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/railtie/configurable.rb:30:in `method_missing'
from /Users/markustorok/Dropbox/2Working/WebDesign/Ruby/rails_projects/speiseplan/config/environment.rb:5:in `<top (required)>'
from /Users/markustorok/Dropbox/2Working/WebDesign/Ruby/rails_projects/speiseplan/config.ru:3:in `require'
from /Users/markustorok/Dropbox/2Working/WebDesign/Ruby/rails_projects/speiseplan/config.ru:3:in `block in <main>'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `instance_eval'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `initialize'
from /Users/markustorok/Dropbox/2Working/WebDesign/Ruby/rails_projects/speiseplan/config.ru:in `new'
from /Users/markustorok/Dropbox/2Working/WebDesign/Ruby/rails_projects/speiseplan/config.ru:in `<main>'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `eval'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `new_from_string'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.5.2/lib/rack/builder.rb:40:in `parse_file'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.5.2/lib/rack/server.rb:277:in `build_app_and_options_from_config'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.5.2/lib/rack/server.rb:199:in `app'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/commands/server.rb:48:in `app'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/rack-1.5.2/lib/rack/server.rb:314:in `wrapped_app'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/commands/server.rb:75:in `start'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/commands.rb:80:in `block in <top (required)>'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/commands.rb:75:in `tap'
from /Users/markustorok/.rvm/gems/ruby-2.0.0-p0/gems/railties-4.0.0.rc1/lib/rails/commands.rb:75:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'