私は activeadmin gem を使用しています。 bundle install を実行すると、sass がインストールされます。bundle show を実行すると、sass(3.2.5) が存在することがわかります。ただし、:assets グループから sass を削除すると、rake コマンドで例外が発生して失敗します。
rake aborted!
cannot load such file -- sass-rails
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:251:in `require'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:251:in `block in require'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:236:in `load_dependency'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:251:in `require'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activeadmin-0.5.1/lib/active_admin/sass/helpers.rb:3:in `<top (required)>'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:251:in `require'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:251:in `block in require'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:236:in `load_dependency'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:251:in `require'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activeadmin-0.5.1/lib/active_admin.rb:11:in `<top (required)>'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activeadmin-0.5.1/lib/activeadmin.rb:1:in `require'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/activeadmin-0.5.1/lib/activeadmin.rb:1:in `<top (required)>'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385/gems/bundler-1.2.4/lib/bundler/runtime.rb:68:in `require'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385/gems/bundler-1.2.4/lib/bundler/runtime.rb:68:in `block (2 levels) in require'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385/gems/bundler-1.2.4/lib/bundler/runtime.rb:66:in `each'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385/gems/bundler-1.2.4/lib/bundler/runtime.rb:66:in `block in require'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385/gems/bundler-1.2.4/lib/bundler/runtime.rb:55:in `each'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385/gems/bundler-1.2.4/lib/bundler/runtime.rb:55:in `require'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385/gems/bundler-1.2.4/lib/bundler.rb:128:in `require'
/Users/kc025858/webApp/data-source-onboarding/config/application.rb:10:in `<top (required)>'
/Users/kc025858/webApp/data-source-onboarding/Rakefile:4:in `require'
/Users/kc025858/webApp/data-source-onboarding/Rakefile:4:in `<top (required)>'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/lib/rake/rake_module.rb:25:in `load'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/lib/rake/rake_module.rb:25:in `load_rakefile'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/lib/rake/application.rb:604:in `raw_load_rakefile'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/lib/rake/application.rb:89:in `block in load_rakefile'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/lib/rake/application.rb:160:in `standard_exception_handling'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/lib/rake/application.rb:88:in `load_rakefile'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/lib/rake/application.rb:72:in `block in run'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/lib/rake/application.rb:160:in `standard_exception_handling'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/lib/rake/application.rb:70:in `run'
/Users/kc025858/webApp/data-source-onboarding/vendor/cache/ruby/1.9.1/gems/rake-0.9.6/bin/rake:37:in `<top (required)>'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385@global/bin/rake:19:in `load'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385@global/bin/rake:19:in `<main>'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385/bin/ruby_noexec_wrapper:14:in `eval'
/Users/kc025858/.rvm/gems/ruby-1.9.3-p385/bin/ruby_noexec_wrapper:14:in `<main>
ActiveAdmin を既にインクルードしているのに、なぜ sass を ur gemfile にインクルードする必要があるのですか?
dependency.txt を見ると、sass が activeadmin の一部であることがわかります。
activeadmin (0.5.1)
arbre (>= 1.0.1)
bourbon (>= 1.0.0)
devise (>= 1.1.2)
fastercsv
formtastic (>= 2.0.0)
inherited_resources (>= 1.3.1)
jquery-rails (>= 1.0.0)
kaminari (>= 0.13.0)
meta_search (>= 0.9.2)
rails (>= 3.0.0)
sass (>= 3.1.0)