I'm using actionview in a Sinatra app and noticed a regression during Mongoid.load! from actionview 4.1.6 to 4.2 which pulls in a couple of rails-* gems,

actionview (4.2.1)
activesupport (= 4.2.1)
builder (~> 3.1)
erubis (~> 2.7.0)
rails-dom-testing (~> 1.0, >= 1.0.5)
rails-html-sanitizer (~> 1.0, >= 1.0.1)

They are listed as dependencies in actionview 4.1.6 but not loaded it seems.

shared/bundle/ruby/2.0.0/gems/mongoid-4.0.2/lib/mongoid/config/environment.rb:22:in {{env_name': undefined method }}env' for Rails:Module (NoMethodError)
from shared/bundle/ruby/2.0.0/gems/mongoid-4.0.2/lib/mongoid/config/environment.rb:39:in `load_yaml'

Rails gets defined by these rails-* gem confusing mongoid into thinking it's a rails app but Rails.env isn't defined. A && defined?(Rails.env) would catch it.

Workaround is gem 'actionview', '~> 4.1.0' in Gemfile.