ActionController::RoutingError: uninitialized constant MicropostsController

ActionController::RoutingError: uninitialized constant MicropostsController

This is my first contribution here, feedback on improving this or future
postings is appreciated :)
Ruby on Rails Tutorial: Learn Web Development with Rails (4)
http://ruby.railstutorial.org/book/ruby-on-rails-tutorial?version=4.0
While working through chapter 10.3, I got stuck. In the end, a misspelled
file name had me chasing ghosts for a few days.
$ rspec spec/requests/authentication_pages_spec.rb No DRb server is
running. Running in local process instead ... ...FF................
Failures:
1) Authentication authorization for non-signed-in users in the Microposts
controller submitting to the create action Failure/Error: before { post
microposts_path } ActionController::RoutingError: uninitialized constant
MicropostsController
./spec/requests/authentication_pages_spec.rb:93:in `block (6 levels) in '
2) Authentication authorization for non-signed-in users in the Microposts
controller submitting to the destroy action Failure/Error: before { delete
micropost_path(FactoryGirl.create(:micropost)) }
ActionController::RoutingError: uninitialized constant
MicropostsController
./spec/requests/authentication_pages_spec.rb:98:in `block (6 levels) in '
Finished in 0.92253 seconds 21 examples, 2 failures
Failed examples:
rspec ./spec/requests/authentication_pages_spec.rb:94 # Authentication
authorization for non-signed-in users in the Microposts controller
submitting to the create action rspec
./spec/requests/authentication_pages_spec.rb:99 # Authentication
authorization for non-signed-in users in the Microposts controller
submitting to the destroy action