Sample Generator Error

Error

rails g model Stuff
      invoke  active_record
      create    db/migrate/20150312174626_create_stuffs.rb
      create    app/models/stuff.rb
[WARNING] Could not load generator "generators/rspec/model/model_generator". Error: uninitialized constant Rspec::Generators::Base::RSpec.
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-rails-3.2.0/lib/generators/rspec.rb:10:in `<class:Base>'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-rails-3.2.0/lib/generators/rspec.rb:9:in `<module:Generators>'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-rails-3.2.0/lib/generators/rspec.rb:7:in `<module:Rspec>'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-rails-3.2.0/lib/generators/rspec.rb:5:in `<top (required)>'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-rails-3.2.0/lib/generators/rspec/model/model_generator.rb:1:in `<top (required)>'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/generators.rb:334:in `block (2 levels) in lookup'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/generators.rb:330:in `each'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/generators.rb:330:in `block in lookup'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/generators.rb:329:in `each'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/generators.rb:329:in `lookup'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/generators.rb:138:in `find_by_namespace'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/generators/base.rb:336:in `prepare_for_invocation'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/group.rb:128:in `_invoke_from_option_test_framework'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/command.rb:27:in `run'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:126:in `invoke_command'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `block in invoke_all'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `each'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `map'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `invoke_all'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/group.rb:232:in `dispatch'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:115:in `invoke'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/group.rb:277:in `block in _invoke_for_class_method'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/shell.rb:68:in `with_padding'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/group.rb:266:in `_invoke_for_class_method'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/group.rb:133:in `_invoke_from_option_orm'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/command.rb:27:in `run'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:126:in `invoke_command'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `block in invoke_all'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `each'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `map'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/invocation.rb:133:in `invoke_all'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/group.rb:232:in `dispatch'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/thor-0.19.1/lib/thor/base.rb:440:in `start'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/generators.rb:157:in `invoke'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/commands/generate.rb:13:in `<top (required)>'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:123:in `require_command!'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:130:in `generate_or_destroy'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:50:in `generate'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
/opt/rubies/2.2.0/lib/ruby/gems/2.2.0/gems/railties-4.2.0/lib/rails/commands.rb:17:in `<top (required)>'
bin/rails:4:in `require'
bin/rails:4:in `<main>'
error    rspec [not found]