I'm following the Ruby on Rails tutorial at RailsTutorial.org and am on section 3.3.1 (/book/static_pages#cha-static_pages) for running 'rails test' for the first time. I'm using the Cloud9 IDE per the recommendation and as far as I can tell I have followed the script exactly. Everything has matched up to this point.
I have also done some searches on the error and come up with comments about something called tmux but I'm not sufficiently experienced enough in Ruby on Rails or Cloud9 to be sure of what I'm doing. Someone also recommended doing 'bundle exec rake test' as an alternative but I get the same error:
2 runs, 2 assertions, 0 failures, 0 errors, 0 skips
/usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/tmux/client.rb:12:in 'version': undefined method '[]' for nil:NilClass (NoMethodError)
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/tmux.rb:69:in '_check_available'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/base.rb:59:in 'initialize'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/detected.rb:100:in 'new'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/detected.rb:100:in '_add'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/detected.rb:62:in 'block (2 levels) in detect'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/detected.rb:60:in 'each'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/detected.rb:60:in 'detect'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/detected.rb:60:in 'block in detect'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/detected.rb:59:in 'each'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier/detected.rb:59:in 'detect'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier.rb:180:in '_detect_or_add_notifiers'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier.rb:198:in '_activate'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier.rb:87:in 'initialize'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier.rb:42:in 'new'
from /usr/local/rvm/gems/ruby-2.4.1/gems/notiffany-0.1.1/lib/notiffany/notifier.rb:42:in 'connect'
from /usr/local/rvm/gems/ruby-2.4.1/gems/guard-2.13.0/lib/guard/notifier.rb:11:in 'connect'
from /usr/local/rvm/gems/ruby-2.4.1/gems/guard-2.13.0/lib/guard/notifier.rb:31:in 'notify'
from /usr/local/rvm/gems/ruby-2.4.1/gems/guard-compat-1.2.1/lib/guard/compat/plugin.rb:113:in 'notify'
from /usr/local/rvm/gems/ruby-2.4.1/gems/guard-minitest-2.4.4/lib/guard/minitest/notifier.rb:31:in 'notify'
from /usr/local/rvm/gems/ruby-2.4.1/gems/guard-minitest-2.4.4/lib/guard/minitest/reporter.rb:10:in 'report'
from /usr/local/rvm/gems/ruby-2.4.1/gems/minitest-5.11.1/lib/minitest.rb:791:in 'each'
from /usr/local/rvm/gems/ruby-2.4.1/gems/minitest-5.11.1/lib/minitest.rb:791:in 'report'
from /usr/local/rvm/gems/ruby-2.4.1/gems/minitest-5.11.1/lib/minitest.rb:141:in 'run'
from /usr/local/rvm/gems/ruby-2.4.1/gems/minitest-5.11.1/lib/minitest.rb:63:in 'block in autorun'
I don't see anything called notiffany in the Gemfile, but I've found it's related to Guard. Since I'm using the specific version indicated by the tutorial, I'm not sure if looking for a newer version there is the fix.
It is possible I'm just not searching for the right keywords, so I apologize if this has been answered before. Any help is appreciated.
-Jay
来源：https://stackoverflow.com/questions/48504534/railstutorial-org-gems-notiffany-0-1-1-lib-notiffany-notifier-tmux-client-rb12