`rspec --configure autotest`抛出“未初始化的常数Class :: FileUtils”

rspec --configure autotest

Autotest loads RSpec\'s Autotest subclass when there is a .rspec file in the project\'s root directory.
/Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/backward_compatibility.rb:20:in `const_missing\': uninitialized constant Class::FileUtils (NameError)
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/command_line_configuration.rb:38:in `create_dot_rspec_file\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/command_line_configuration.rb:29:in `generate\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/command_line_configuration.rb:12:in `run\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/option_parser.rb:101:in `block (2 levels) in parser\'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1277:in `call\'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1277:in `block in parse_in_order\'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1264:in `catch\'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1264:in `parse_in_order\'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1258:in `order!\'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1349:in `permute!\'
    from /Users/brennon/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/optparse.rb:1370:in `parse!\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/option_parser.rb:18:in `parse!\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/option_parser.rb:4:in `parse!\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/configuration_options.rb:88:in `command_line_options\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/configuration_options.rb:122:in `custom_options_file\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/configuration_options.rb:65:in `parse_options\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/runner.rb:41:in `run\'
    from /Users/brennon/.rvm/gems/ruby-1.9.2-p0@timekeepa/gems/rspec-core-2.5.1/lib/rspec/core/runner.rb:10:in `block in autorun\'

rspec

autotest

require \'fileutils\'