add gems rails-spec and capybara. do rails generate rpec:install
in the top page when not signed in, test that the page have h1 Articles and title Articles
in the top page when signed in, test the page has link "Sign in the with Twitter"
add bootstrap
add some style to custom.css.scss
change value of the text in have_link of articles_pages_rspec.rb
add faker gem and add dummy data to sample_data.rake
add will_paginate in Gemfile and implement paginate, but do not test pagination.
make twitter_ominauth_helper.rb and modify some files
remove sessions_helper.rb
add spork and twitter gems to Gemfile. test the authentication by using mock.