运行时Ruby / Rails rspec下载错误

运行时出现以下错误

saasbook@saasbook:~/Documents/ruby-calisthenics$ rspec

错误信息

/home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/formatters.rb:167:in `find_formatter': Formatter 'nested' unknown - maybe you meant 'documentation' or 'progress'?. (ArgumentError)
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/formatters.rb:126:in `add'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/configuration.rb:624:in `add_formatter'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/configuration_options.rb:106:in `block in load_formatters_into'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/configuration_options.rb:106:in `each'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/configuration_options.rb:106:in `load_formatters_into'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/configuration_options.rb:24:in `configure'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/runner.rb:96:in `setup'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/runner.rb:85:in `run'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/runner.rb:70:in `run'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/lib/rspec/core/runner.rb:38:in `invoke'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/gems/rspec-core-3.0.3/exe/rspec:4:in `<top (required)>'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/bin/rspec:23:in `load'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/bin/rspec:23:in `<main>'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/bin/ruby_executable_hooks:15:in `eval'
from /home/saasbook/.rvm/gems/ruby-2.0.0-p481/bin/ruby_executable_hooks:15:in `<main>'

我是Ruby和Rails的新手。我一直都在遇到兼容性问题，我们将不胜感激！

试图在以下位置运行rspec的文件目录的背景有点 这是我正在参加的在线课程的文件。它包含所需的lib和spec文件。但是错误即时消息似乎与我的rspec下载有关。