RuntimeError: can't modify frozen Array when running rspec in rails 5.1

Question

I recently upgraded to Rails 5.1 from v4.3 and am now getting this error when running tests:

An error occurred while loading 

./spec/controllers/admin/capac         


        

Answer 1

In my case recent rails_admin required some addition

RuntimeError: Required middlewares for RailsAdmin are not added
To fix tihs, add

config.middleware.use ActionDispatch::Flash

to config/application.rb.

Then all rspecs became green again.