diff --git a/.gitignore b/.gitignore
index 050c9d9..acd799b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,6 @@
 /log/*
 !/log/.keep
 /tmp
+
+# Ignore encrypted secrets key file.
+config/secrets.yml.key
diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..7f9e49d
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,12 @@
+Rails:
+  Enabled: true
+AllCops:
+  AutoCorrect: true
+  TargetRubyVersion: 2.4.0
+  Include:
+    - '**/Gemfile'
+    - '**/Rakefile'
+  Exclude:
+   - 'bin/*'
+   - 'db/seeds.rb'
+   - 'db/schema.rb'
diff --git a/Gemfile b/Gemfile
index 841e0c9..4604d1c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,34 +1,26 @@
-source 'https://rubygems.org'
+# frozen_string_literal: true
 
+source 'https://rubygems.org'
+ruby '2.4.1'
 
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
-gem 'rails', '4.2.6'
+gem 'rails', '5.2.1'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
-# Use SCSS for stylesheets
-gem 'sass-rails', '~> 5.0'
-# Use Uglifier as compressor for JavaScript assets
-gem 'uglifier', '>= 1.3.0'
-# Use CoffeeScript for .coffee assets and views
-gem 'coffee-rails', '~> 4.1.0'
 # See https://github.com/rails/execjs#readme for more supported runtimes
 # gem 'therubyracer', platforms: :ruby
 
-# Use jquery as the JavaScript library
-gem 'jquery-rails'
-# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
-gem 'turbolinks'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 gem 'jbuilder', '~> 2.0'
 # bundle exec rake doc:rails generates the API under doc/api.
 gem 'sdoc', '~> 0.4.0', group: :doc
 
-gem 'acts-as-taggable-on', '~> 3.5.0'
-gem 'acts_as_follower', '~> 0.2.1'
-gem 'devise', '~> 4.2.0'
+gem 'acts-as-taggable-on', git: 'https://github.com/mbleigh/acts-as-taggable-on'
+gem 'acts_as_follower'
+gem 'devise'
 gem 'jwt', '~> 1.5.4'
-gem 'rack-cors', '~> 0.4.0'
 gem 'puma'
+gem 'rack-cors', require: 'rack/cors'
 
 # Use ActiveModel has_secure_password
 # gem 'bcrypt', '~> 3.1.7'
@@ -42,13 +34,12 @@ gem 'puma'
 group :development, :test do
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
   gem 'byebug'
+  gem 'listen'
 end
 
 group :development do
-  # Access an IRB console on exception pages or by using <%= console %> in views
-  gem 'web-console', '~> 2.0'
-
   # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
+  gem 'pry'
+  gem 'rubocop', require: false
   gem 'spring'
 end
-
diff --git a/Gemfile.lock b/Gemfile.lock
index d8a673f..023198f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,187 +1,203 @@
+GIT
+  remote: https://github.com/mbleigh/acts-as-taggable-on
+  revision: 69322267029b54fe42be9a05e248df9de289a65b
+  specs:
+    acts-as-taggable-on (6.0.1)
+      activerecord (~> 5.0)
+
 GEM
   remote: https://rubygems.org/
   specs:
-    actionmailer (4.2.6)
-      actionpack (= 4.2.6)
-      actionview (= 4.2.6)
-      activejob (= 4.2.6)
+    actioncable (5.2.1)
+      actionpack (= 5.2.1)
+      nio4r (~> 2.0)
+      websocket-driver (>= 0.6.1)
+    actionmailer (5.2.1)
+      actionpack (= 5.2.1)
+      actionview (= 5.2.1)
+      activejob (= 5.2.1)
       mail (~> 2.5, >= 2.5.4)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-    actionpack (4.2.6)
-      actionview (= 4.2.6)
-      activesupport (= 4.2.6)
-      rack (~> 1.6)
-      rack-test (~> 0.6.2)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionview (4.2.6)
-      activesupport (= 4.2.6)
-      builder (~> 3.1)
-      erubis (~> 2.7.0)
-      rails-dom-testing (~> 1.0, >= 1.0.5)
+      rails-dom-testing (~> 2.0)
+    actionpack (5.2.1)
+      actionview (= 5.2.1)
+      activesupport (= 5.2.1)
+      rack (~> 2.0)
+      rack-test (>= 0.6.3)
+      rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    activejob (4.2.6)
-      activesupport (= 4.2.6)
-      globalid (>= 0.3.0)
-    activemodel (4.2.6)
-      activesupport (= 4.2.6)
+    actionview (5.2.1)
+      activesupport (= 5.2.1)
       builder (~> 3.1)
-    activerecord (4.2.6)
-      activemodel (= 4.2.6)
-      activesupport (= 4.2.6)
-      arel (~> 6.0)
-    activesupport (4.2.6)
-      i18n (~> 0.7)
-      json (~> 1.7, >= 1.7.7)
+      erubi (~> 1.4)
+      rails-dom-testing (~> 2.0)
+      rails-html-sanitizer (~> 1.0, >= 1.0.3)
+    activejob (5.2.1)
+      activesupport (= 5.2.1)
+      globalid (>= 0.3.6)
+    activemodel (5.2.1)
+      activesupport (= 5.2.1)
+    activerecord (5.2.1)
+      activemodel (= 5.2.1)
+      activesupport (= 5.2.1)
+      arel (>= 9.0)
+    activestorage (5.2.1)
+      actionpack (= 5.2.1)
+      activerecord (= 5.2.1)
+      marcel (~> 0.3.1)
+    activesupport (5.2.1)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (>= 0.7, < 2)
       minitest (~> 5.1)
-      thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
-    acts-as-taggable-on (3.5.0)
-      activerecord (>= 3.2, < 5)
     acts_as_follower (0.2.1)
-    arel (6.0.3)
-    bcrypt (3.1.11)
-    binding_of_caller (0.7.2)
-      debug_inspector (>= 0.0.1)
-    builder (3.2.2)
-    byebug (9.0.5)
-    coffee-rails (4.1.1)
-      coffee-script (>= 2.2.0)
-      railties (>= 4.0.0, < 5.1.x)
-    coffee-script (2.4.1)
-      coffee-script-source
-      execjs
-    coffee-script-source (1.10.0)
-    concurrent-ruby (1.0.2)
-    debug_inspector (0.0.2)
-    devise (4.2.0)
+    arel (9.0.0)
+    ast (2.4.0)
+    bcrypt (3.1.12)
+    builder (3.2.3)
+    byebug (10.0.2)
+    coderay (1.1.2)
+    concurrent-ruby (1.0.5)
+    crass (1.0.4)
+    devise (4.5.0)
       bcrypt (~> 3.0)
       orm_adapter (~> 0.1)
-      railties (>= 4.1.0, < 5.1)
+      railties (>= 4.1.0, < 6.0)
       responders
       warden (~> 1.2.3)
-    erubis (2.7.0)
-    execjs (2.7.0)
-    globalid (0.3.6)
-      activesupport (>= 4.1.0)
-    i18n (0.7.0)
-    jbuilder (2.5.0)
-      activesupport (>= 3.0.0, < 5.1)
-      multi_json (~> 1.2)
-    jquery-rails (4.1.1)
-      rails-dom-testing (>= 1, < 3)
-      railties (>= 4.2.0)
-      thor (>= 0.14, < 2.0)
-    json (1.8.3)
-    jwt (1.5.4)
-    loofah (2.0.3)
+    erubi (1.7.1)
+    ffi (1.9.25)
+    globalid (0.4.1)
+      activesupport (>= 4.2.0)
+    i18n (1.1.1)
+      concurrent-ruby (~> 1.0)
+    jaro_winkler (1.5.1)
+    jbuilder (2.7.0)
+      activesupport (>= 4.2.0)
+      multi_json (>= 1.2)
+    json (1.8.6)
+    jwt (1.5.6)
+    listen (3.1.5)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+      ruby_dep (~> 1.2)
+    loofah (2.2.2)
+      crass (~> 1.0.2)
       nokogiri (>= 1.5.9)
-    mail (2.6.4)
-      mime-types (>= 1.16, < 4)
-    mime-types (3.1)
-      mime-types-data (~> 3.2015)
-    mime-types-data (3.2016.0521)
-    mini_portile2 (2.1.0)
-    minitest (5.9.0)
-    multi_json (1.12.1)
-    nokogiri (1.6.8)
-      mini_portile2 (~> 2.1.0)
-      pkg-config (~> 1.1.7)
+    mail (2.7.1)
+      mini_mime (>= 0.1.1)
+    marcel (0.3.3)
+      mimemagic (~> 0.3.2)
+    method_source (0.9.0)
+    mimemagic (0.3.2)
+    mini_mime (1.0.1)
+    mini_portile2 (2.3.0)
+    minitest (5.11.3)
+    multi_json (1.13.1)
+    nio4r (2.3.1)
+    nokogiri (1.8.5)
+      mini_portile2 (~> 2.3.0)
     orm_adapter (0.5.0)
-    pkg-config (1.1.7)
-    puma (3.4.0)
-    rack (1.6.4)
-    rack-cors (0.4.0)
-    rack-test (0.6.3)
-      rack (>= 1.0)
-    rails (4.2.6)
-      actionmailer (= 4.2.6)
-      actionpack (= 4.2.6)
-      actionview (= 4.2.6)
-      activejob (= 4.2.6)
-      activemodel (= 4.2.6)
-      activerecord (= 4.2.6)
-      activesupport (= 4.2.6)
-      bundler (>= 1.3.0, < 2.0)
-      railties (= 4.2.6)
-      sprockets-rails
-    rails-deprecated_sanitizer (1.0.3)
-      activesupport (>= 4.2.0.alpha)
-    rails-dom-testing (1.0.7)
-      activesupport (>= 4.2.0.beta, < 5.0)
-      nokogiri (~> 1.6.0)
-      rails-deprecated_sanitizer (>= 1.0.1)
-    rails-html-sanitizer (1.0.3)
-      loofah (~> 2.0)
-    railties (4.2.6)
-      actionpack (= 4.2.6)
-      activesupport (= 4.2.6)
+    parallel (1.12.1)
+    parser (2.5.1.2)
+      ast (~> 2.4.0)
+    powerpack (0.1.2)
+    pry (0.11.3)
+      coderay (~> 1.1.0)
+      method_source (~> 0.9.0)
+    puma (3.12.0)
+    rack (2.0.5)
+    rack-cors (1.0.2)
+    rack-test (1.1.0)
+      rack (>= 1.0, < 3)
+    rails (5.2.1)
+      actioncable (= 5.2.1)
+      actionmailer (= 5.2.1)
+      actionpack (= 5.2.1)
+      actionview (= 5.2.1)
+      activejob (= 5.2.1)
+      activemodel (= 5.2.1)
+      activerecord (= 5.2.1)
+      activestorage (= 5.2.1)
+      activesupport (= 5.2.1)
+      bundler (>= 1.3.0)
+      railties (= 5.2.1)
+      sprockets-rails (>= 2.0.0)
+    rails-dom-testing (2.0.3)
+      activesupport (>= 4.2.0)
+      nokogiri (>= 1.6)
+    rails-html-sanitizer (1.0.4)
+      loofah (~> 2.2, >= 2.2.2)
+    railties (5.2.1)
+      actionpack (= 5.2.1)
+      activesupport (= 5.2.1)
+      method_source
       rake (>= 0.8.7)
-      thor (>= 0.18.1, < 2.0)
-    rake (11.2.2)
-    rdoc (4.2.2)
-      json (~> 1.4)
-    responders (2.2.0)
-      railties (>= 4.2.0, < 5.1)
-    sass (3.4.22)
-    sass-rails (5.0.5)
-      railties (>= 4.0.0, < 6)
-      sass (~> 3.1)
-      sprockets (>= 2.8, < 4.0)
-      sprockets-rails (>= 2.0, < 4.0)
-      tilt (>= 1.1, < 3)
-    sdoc (0.4.1)
+      thor (>= 0.19.0, < 2.0)
+    rainbow (3.0.0)
+    rake (12.3.1)
+    rb-fsevent (0.10.3)
+    rb-inotify (0.9.10)
+      ffi (>= 0.5.0, < 2)
+    rdoc (4.3.0)
+    responders (2.4.0)
+      actionpack (>= 4.2.0, < 5.3)
+      railties (>= 4.2.0, < 5.3)
+    rubocop (0.59.2)
+      jaro_winkler (~> 1.5.1)
+      parallel (~> 1.10)
+      parser (>= 2.5, != 2.5.1.1)
+      powerpack (~> 0.1)
+      rainbow (>= 2.2.2, < 4.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (~> 1.0, >= 1.0.1)
+    ruby-progressbar (1.10.0)
+    ruby_dep (1.5.0)
+    sdoc (0.4.2)
       json (~> 1.7, >= 1.7.7)
       rdoc (~> 4.0)
-    spring (1.7.2)
-    sprockets (3.6.3)
+    spring (2.0.2)
+      activesupport (>= 4.2)
+    sprockets (3.7.2)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
-    sprockets-rails (3.1.1)
+    sprockets-rails (3.2.1)
       actionpack (>= 4.0)
       activesupport (>= 4.0)
       sprockets (>= 3.0.0)
-    sqlite3 (1.3.11)
-    thor (0.19.1)
-    thread_safe (0.3.5)
-    tilt (2.0.5)
-    turbolinks (5.0.0)
-      turbolinks-source (~> 5)
-    turbolinks-source (5.0.0)
-    tzinfo (1.2.2)
+    sqlite3 (1.3.13)
+    thor (0.20.0)
+    thread_safe (0.3.6)
+    tzinfo (1.2.5)
       thread_safe (~> 0.1)
-    uglifier (3.0.0)
-      execjs (>= 0.3.0, < 3)
-    warden (1.2.6)
+    unicode-display_width (1.4.0)
+    warden (1.2.7)
       rack (>= 1.0)
-    web-console (2.3.0)
-      activemodel (>= 4.0)
-      binding_of_caller (>= 0.7.2)
-      railties (>= 4.0)
-      sprockets-rails (>= 2.0, < 4.0)
+    websocket-driver (0.7.0)
+      websocket-extensions (>= 0.1.0)
+    websocket-extensions (0.1.3)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  acts-as-taggable-on (~> 3.5.0)
-  acts_as_follower (~> 0.2.1)
+  acts-as-taggable-on!
+  acts_as_follower
   byebug
-  coffee-rails (~> 4.1.0)
-  devise (~> 4.2.0)
+  devise
   jbuilder (~> 2.0)
-  jquery-rails
   jwt (~> 1.5.4)
+  listen
+  pry
   puma
-  rack-cors (~> 0.4.0)
-  rails (= 4.2.6)
-  sass-rails (~> 5.0)
+  rack-cors
+  rails (= 5.2.1)
+  rubocop
   sdoc (~> 0.4.0)
   spring
   sqlite3
-  turbolinks
-  uglifier (>= 1.3.0)
-  web-console (~> 2.0)
+
+RUBY VERSION
+   ruby 2.4.1p111
 
 BUNDLED WITH
-   1.10.6
+   1.16.0
diff --git a/Rakefile b/Rakefile
index ba6b733..da4efd5 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Add your own tasks in files placed in lib/tasks ending in .rake,
 # for example lib/tasks/capistrano.rake, and they will automatically be available to Rake.
 
diff --git a/app/assets/images/.keep b/app/assets/images/.keep
deleted file mode 100644
index e69de29..0000000
diff --git a/app/assets/javascripts/application.js b/app/assets/javascripts/application.js
deleted file mode 100644
index e07c5a8..0000000
--- a/app/assets/javascripts/application.js
+++ /dev/null
@@ -1,16 +0,0 @@
-// This is a manifest file that'll be compiled into application.js, which will include all the files
-// listed below.
-//
-// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, vendor/assets/javascripts,
-// or any plugin's vendor/assets/javascripts directory can be referenced here using a relative path.
-//
-// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
-// compiled file.
-//
-// Read Sprockets README (https://github.com/rails/sprockets#sprockets-directives) for details
-// about supported directives.
-//
-//= require jquery
-//= require jquery_ujs
-//= require turbolinks
-//= require_tree .
diff --git a/app/assets/stylesheets/application.css b/app/assets/stylesheets/application.css
deleted file mode 100644
index f9cd5b3..0000000
--- a/app/assets/stylesheets/application.css
+++ /dev/null
@@ -1,15 +0,0 @@
-/*
- * This is a manifest file that'll be compiled into application.css, which will include all the files
- * listed below.
- *
- * Any CSS and SCSS file within this directory, lib/assets/stylesheets, vendor/assets/stylesheets,
- * or any plugin's vendor/assets/stylesheets directory can be referenced here using a relative path.
- *
- * You're free to add application-wide styles to this file and they'll appear at the bottom of the
- * compiled file so the styles you add here take precedence over styles defined in any styles
- * defined in the other CSS/SCSS files in this directory. It is generally better to create a new
- * file per style scope.
- *
- *= require_tree .
- *= require_self
- */
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 5e6b91b..d3cf437 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -1,11 +1,10 @@
-class ApplicationController < ActionController::Base
-  # Prevent CSRF attacks by raising an exception.
-  # For APIs, you may want to use :null_session instead.
-  protect_from_forgery with: :null_session
+# frozen_string_literal: true
 
+class ApplicationController < ActionController::API
   respond_to :json
 
-  before_action :underscore_params!
+  include ActionController::HttpAuthentication::Token::ControllerMethods
+
   before_action :configure_permitted_parameters, if: :devise_controller?
   before_action :authenticate_user
 
@@ -16,20 +15,20 @@ def configure_permitted_parameters
   end
 
   def authenticate_user
-    if request.headers['Authorization'].present?
-      authenticate_or_request_with_http_token do |token|
-        begin
-          jwt_payload = JWT.decode(token, Rails.application.secrets.secret_key_base).first
-
-          @current_user_id = jwt_payload['id']
-        rescue JWT::ExpiredSignature, JWT::VerificationError, JWT::DecodeError
-          head :unauthorized
-        end
+    return if request.headers['Authorization'].blank?
+
+    authenticate_or_request_with_http_token do |token|
+      begin
+        jwt_payload = JWT.decode(token, Rails.application.secrets.secret_key_base).first
+
+        @current_user_id = jwt_payload['id']
+      rescue JWT::ExpiredSignature, JWT::VerificationError, JWT::DecodeError
+        head :unauthorized
       end
     end
   end
 
-  def authenticate_user!(options = {})
+  def authenticate_user!(_options = {})
     head :unauthorized unless signed_in?
   end
 
@@ -40,8 +39,4 @@ def current_user
   def signed_in?
     @current_user_id.present?
   end
-
-  def underscore_params!
-    params.deep_transform_keys!(&:underscore)
-  end
 end
diff --git a/app/controllers/articles_controller.rb b/app/controllers/articles_controller.rb
index 8c12015..2888939 100644
--- a/app/controllers/articles_controller.rb
+++ b/app/controllers/articles_controller.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 class ArticlesController < ApplicationController
-  before_action :authenticate_user!, except: [:index, :show]
+  before_action :authenticate_user!, except: %i[index show]
 
   def index
     @articles = Article.all.includes(:user)
@@ -35,11 +37,11 @@ def create
   end
 
   def show
-    @article = Article.find_by_slug!(params[:slug])
+    @article = Article.find_by!(slug: params[:slug])
   end
 
   def update
-    @article = Article.find_by_slug!(params[:slug])
+    @article = Article.find_by!(slug: params[:slug])
 
     if @article.user_id == @current_user_id
       @article.update_attributes(article_params)
@@ -51,7 +53,7 @@ def update
   end
 
   def destroy
-    @article = Article.find_by_slug!(params[:slug])
+    @article = Article.find_by!(slug: params[:slug])
 
     if @article.user_id == @current_user_id
       @article.destroy
diff --git a/app/controllers/comments_controller.rb b/app/controllers/comments_controller.rb
index 2961226..b5b1e39 100644
--- a/app/controllers/comments_controller.rb
+++ b/app/controllers/comments_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CommentsController < ApplicationController
   before_action :authenticate_user!, except: [:index]
   before_action :find_article!
@@ -31,6 +33,6 @@ def comment_params
   end
 
   def find_article!
-    @article = Article.find_by_slug!(params[:article_slug])
+    @article = Article.find_by!(slug: params[:article_slug])
   end
 end
diff --git a/app/controllers/favorites_controller.rb b/app/controllers/favorites_controller.rb
index c1cb2eb..28e38b1 100644
--- a/app/controllers/favorites_controller.rb
+++ b/app/controllers/favorites_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class FavoritesController < ApplicationController
   before_action :authenticate_user!
   before_action :find_article!
@@ -17,6 +19,6 @@ def destroy
   private
 
   def find_article!
-    @article = Article.find_by_slug!(params[:article_slug])
+    @article = Article.find_by!(slug: params[:article_slug])
   end
 end
diff --git a/app/controllers/follows_controller.rb b/app/controllers/follows_controller.rb
index d1a62c2..fa6f674 100644
--- a/app/controllers/follows_controller.rb
+++ b/app/controllers/follows_controller.rb
@@ -1,8 +1,10 @@
+# frozen_string_literal: true
+
 class FollowsController < ApplicationController
   before_action :authenticate_user!
 
   def create
-    @user = User.find_by_username!(params[:profile_username])
+    @user = User.find_by!(username: params[:profile_username])
 
     current_user.follow(@user) if current_user.id != @user.id
 
@@ -10,7 +12,7 @@ def create
   end
 
   def destroy
-    @user = User.find_by_username!(params[:profile_username])
+    @user = User.find_by!(username: params[:profile_username])
 
     current_user.stop_following(@user) if current_user.id != @user.id
 
diff --git a/app/controllers/profiles_controller.rb b/app/controllers/profiles_controller.rb
index a0b2bda..95898c8 100644
--- a/app/controllers/profiles_controller.rb
+++ b/app/controllers/profiles_controller.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 class ProfilesController < ApplicationController
   def show
-    @user = User.find_by_username(params[:username])
+    @user = User.find_by(username: params[:username])
   end
 end
diff --git a/app/controllers/sessions_controller.rb b/app/controllers/sessions_controller.rb
index 8324f36..f2cdf07 100644
--- a/app/controllers/sessions_controller.rb
+++ b/app/controllers/sessions_controller.rb
@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 class SessionsController < Devise::SessionsController
   def create
-    user = User.find_by_email(sign_in_params[:email])
+    user = User.find_by(email: sign_in_params[:email])
 
     if user && user.valid_password?(sign_in_params[:password])
       @current_user = user
diff --git a/app/controllers/tags_controller.rb b/app/controllers/tags_controller.rb
index 07a90f1..ac376ad 100644
--- a/app/controllers/tags_controller.rb
+++ b/app/controllers/tags_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class TagsController < ApplicationController
   def index
     render json: { tags: Article.tag_counts.most_used.map(&:name) }
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 05ce519..43e2eec 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -1,8 +1,9 @@
+# frozen_string_literal: true
+
 class UsersController < ApplicationController
   before_action :authenticate_user!
 
-  def show
-  end
+  def show; end
 
   def update
     if current_user.update_attributes(user_params)
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index de6be79..15b06f0 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 module ApplicationHelper
 end
diff --git a/app/models/application_record.rb b/app/models/application_record.rb
new file mode 100644
index 0000000..71fbba5
--- /dev/null
+++ b/app/models/application_record.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class ApplicationRecord < ActiveRecord::Base
+  self.abstract_class = true
+end
diff --git a/app/models/article.rb b/app/models/article.rb
index fb97283..3ec81a2 100644
--- a/app/models/article.rb
+++ b/app/models/article.rb
@@ -1,10 +1,12 @@
-class Article < ActiveRecord::Base
+# frozen_string_literal: true
+
+class Article < ApplicationRecord
   belongs_to :user
   has_many :favorites, dependent: :destroy
   has_many :comments, dependent: :destroy
 
   scope :authored_by, ->(username) { where(user: User.where(username: username)) }
-  scope :favorited_by, -> (username) { joins(:favorites).where(favorites: { user: User.where(username: username) }) }
+  scope :favorited_by, ->(username) { joins(:favorites).where(favorites: { user: User.where(username: username) }) }
 
   acts_as_taggable
 
diff --git a/app/models/comment.rb b/app/models/comment.rb
index 21b0ceb..d3627db 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -1,4 +1,6 @@
-class Comment < ActiveRecord::Base
+# frozen_string_literal: true
+
+class Comment < ApplicationRecord
   belongs_to :user
   belongs_to :article
 
diff --git a/app/models/favorite.rb b/app/models/favorite.rb
index 249d476..3e5b435 100644
--- a/app/models/favorite.rb
+++ b/app/models/favorite.rb
@@ -1,4 +1,6 @@
-class Favorite < ActiveRecord::Base
+# frozen_string_literal: true
+
+class Favorite < ApplicationRecord
   belongs_to :user
   belongs_to :article, counter_cache: true
 end
diff --git a/app/models/follow.rb b/app/models/follow.rb
index 125ec68..0746982 100644
--- a/app/models/follow.rb
+++ b/app/models/follow.rb
@@ -1,5 +1,6 @@
-class Follow < ActiveRecord::Base
+# frozen_string_literal: true
 
+class Follow < ApplicationRecord
   extend ActsAsFollower::FollowerLib
   extend ActsAsFollower::FollowScopes
 
@@ -8,7 +9,6 @@ class Follow < ActiveRecord::Base
   belongs_to :follower,   polymorphic: true
 
   def block!
-    self.update_attribute(:blocked, true)
+    update_attribute(:blocked, true)
   end
-
 end
diff --git a/app/models/user.rb b/app/models/user.rb
index 39e9c0b..dfd056d 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -1,4 +1,6 @@
-class User < ActiveRecord::Base
+# frozen_string_literal: true
+
+class User < ApplicationRecord
   # Include default devise modules. Others available are:
   # :confirmable, :lockable, :timeoutable and :omniauthable
   devise :database_authenticatable, :registerable,
@@ -11,7 +13,6 @@ class User < ActiveRecord::Base
   acts_as_follower
   acts_as_followable
 
-
   validates :username, uniqueness: { case_sensitive: true },
                        format: { with: /\A[a-zA-Z0-9]+\z/ },
                        presence: true,
diff --git a/app/views/articles/_article.json.jbuilder b/app/views/articles/_article.json.jbuilder
index ff25e82..8bf1117 100644
--- a/app/views/articles/_article.json.jbuilder
+++ b/app/views/articles/_article.json.jbuilder
@@ -1,4 +1,6 @@
-json.(article, :title, :slug, :body, :created_at, :updated_at, :description, :tag_list)
+# frozen_string_literal: true
+
+json.call(article, :title, :slug, :body, :created_at, :updated_at, :description, :tag_list)
 json.author article.user, partial: 'profiles/profile', as: :user
 json.favorited signed_in? ? current_user.favorited?(article) : false
 json.favorites_count article.favorites_count || 0
diff --git a/app/views/articles/index.json.jbuilder b/app/views/articles/index.json.jbuilder
index 0273f37..974df02 100644
--- a/app/views/articles/index.json.jbuilder
+++ b/app/views/articles/index.json.jbuilder
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 json.articles do |json|
   json.array! @articles, partial: 'articles/article', as: :article
 end
diff --git a/app/views/articles/show.json.jbuilder b/app/views/articles/show.json.jbuilder
index 57d5fbb..84ecc16 100644
--- a/app/views/articles/show.json.jbuilder
+++ b/app/views/articles/show.json.jbuilder
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 json.article do |json|
   json.partial! 'articles/article', article: @article
 end
diff --git a/app/views/comments/_comment.json.jbuilder b/app/views/comments/_comment.json.jbuilder
index 24f463b..5f82280 100644
--- a/app/views/comments/_comment.json.jbuilder
+++ b/app/views/comments/_comment.json.jbuilder
@@ -1,2 +1,4 @@
-json.(comment, :id, :created_at, :updated_at, :body)
+# frozen_string_literal: true
+
+json.call(comment, :id, :created_at, :updated_at, :body)
 json.author comment.user, partial: 'profiles/profile', as: :user
diff --git a/app/views/comments/create.json.jbuilder b/app/views/comments/create.json.jbuilder
index ccf728d..e9773ab 100644
--- a/app/views/comments/create.json.jbuilder
+++ b/app/views/comments/create.json.jbuilder
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 json.comment do |json|
   json.partial! 'comments/comment', comment: @comment
 end
diff --git a/app/views/comments/index.json.jbuilder b/app/views/comments/index.json.jbuilder
index a79c11e..502bea2 100644
--- a/app/views/comments/index.json.jbuilder
+++ b/app/views/comments/index.json.jbuilder
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 json.comments do |json|
   json.array! @comments, partial: 'comments/comment', as: :comment
 end
diff --git a/app/views/devise/registrations/create.json.jbuilder b/app/views/devise/registrations/create.json.jbuilder
index c5ec3e5..60f1da9 100644
--- a/app/views/devise/registrations/create.json.jbuilder
+++ b/app/views/devise/registrations/create.json.jbuilder
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 json.user do |json|
   json.partial! 'users/user', user: current_user
 end
diff --git a/app/views/devise/sessions/create.json.jbuilder b/app/views/devise/sessions/create.json.jbuilder
index c5ec3e5..60f1da9 100644
--- a/app/views/devise/sessions/create.json.jbuilder
+++ b/app/views/devise/sessions/create.json.jbuilder
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 json.user do |json|
   json.partial! 'users/user', user: current_user
 end
diff --git a/app/views/layouts/application.html.erb b/app/views/layouts/application.html.erb
deleted file mode 100644
index 77d37b8..0000000
--- a/app/views/layouts/application.html.erb
+++ /dev/null
@@ -1,14 +0,0 @@
-<!DOCTYPE html>
-<html>
-<head>
-  <title>Conduit</title>
-  <%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track' => true %>
-  <%= javascript_include_tag 'application', 'data-turbolinks-track' => true %>
-  <%= csrf_meta_tags %>
-</head>
-<body>
-
-<%= yield %>
-
-</body>
-</html>
diff --git a/app/views/profiles/_profile.json.jbuilder b/app/views/profiles/_profile.json.jbuilder
index e5834e6..ded3482 100644
--- a/app/views/profiles/_profile.json.jbuilder
+++ b/app/views/profiles/_profile.json.jbuilder
@@ -1,3 +1,5 @@
-json.(user, :username, :bio)
+# frozen_string_literal: true
+
+json.call(user, :username, :bio)
 json.image user.image || 'https://static.productionready.io/images/smiley-cyrus.jpg'
 json.following signed_in? ? current_user.following?(user) : false
diff --git a/app/views/profiles/show.json.jbuilder b/app/views/profiles/show.json.jbuilder
index 6aaeac2..887ba8e 100644
--- a/app/views/profiles/show.json.jbuilder
+++ b/app/views/profiles/show.json.jbuilder
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 json.profile do |json|
   json.partial! 'profiles/profile', user: @user
 end
diff --git a/app/views/users/_user.json.jbuilder b/app/views/users/_user.json.jbuilder
index c361ada..a7ff346 100644
--- a/app/views/users/_user.json.jbuilder
+++ b/app/views/users/_user.json.jbuilder
@@ -1,2 +1,4 @@
-json.(user, :id, :email, :username, :bio, :image)
+# frozen_string_literal: true
+
+json.call(user, :id, :email, :username, :bio, :image)
 json.token user.generate_jwt
diff --git a/app/views/users/show.json.jbuilder b/app/views/users/show.json.jbuilder
index c5ec3e5..60f1da9 100644
--- a/app/views/users/show.json.jbuilder
+++ b/app/views/users/show.json.jbuilder
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 json.user do |json|
   json.partial! 'users/user', user: current_user
 end
diff --git a/bin/bundle b/bin/bundle
index 7ee2081..66e9889 100755
--- a/bin/bundle
+++ b/bin/bundle
@@ -1,3 +1,3 @@
-#!/usr/bin/env ruby2.2
+#!/usr/bin/env ruby
 ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
 load Gem.bin_path('bundler', 'bundle')
diff --git a/bin/rails b/bin/rails
index efa17f8..0739660 100755
--- a/bin/rails
+++ b/bin/rails
@@ -1,9 +1,4 @@
-#!/usr/bin/env ruby2.2
-begin
-  load File.expand_path('../spring', __FILE__)
-rescue LoadError => e
-  raise unless e.message.include?('spring')
-end
-APP_PATH = File.expand_path('../../config/application', __FILE__)
+#!/usr/bin/env ruby
+APP_PATH = File.expand_path('../config/application', __dir__)
 require_relative '../config/boot'
 require 'rails/commands'
diff --git a/bin/rake b/bin/rake
index 3d6d183..1724048 100755
--- a/bin/rake
+++ b/bin/rake
@@ -1,9 +1,4 @@
-#!/usr/bin/env ruby2.2
-begin
-  load File.expand_path('../spring', __FILE__)
-rescue LoadError => e
-  raise unless e.message.include?('spring')
-end
+#!/usr/bin/env ruby
 require_relative '../config/boot'
 require 'rake'
 Rake.application.run
diff --git a/bin/setup b/bin/setup
index a242dbb..78c4e86 100755
--- a/bin/setup
+++ b/bin/setup
@@ -1,29 +1,38 @@
-#!/usr/bin/env ruby2.2
+#!/usr/bin/env ruby
 require 'pathname'
+require 'fileutils'
+include FileUtils
 
 # path to your application root.
-APP_ROOT = Pathname.new File.expand_path('../../',  __FILE__)
+APP_ROOT = Pathname.new File.expand_path('../../', __FILE__)
 
-Dir.chdir APP_ROOT do
+def system!(*args)
+  system(*args) || abort("\n== Command #{args} failed ==")
+end
+
+chdir APP_ROOT do
   # This script is a starting point to setup your application.
-  # Add necessary setup steps to this file:
+  # Add necessary setup steps to this file.
+
+  puts '== Installing dependencies =='
+  system! 'gem install bundler --conservative'
+  system('bundle check') || system!('bundle install')
+
+  # Install JavaScript dependencies if using Yarn
+  # system('bin/yarn')
 
-  puts "== Installing dependencies =="
-  system "gem install bundler --conservative"
-  system "bundle check || bundle install"
 
   # puts "\n== Copying sample files =="
-  # unless File.exist?("config/database.yml")
-  #   system "cp config/database.yml.sample config/database.yml"
+  # unless File.exist?('config/database.yml')
+  #   cp 'config/database.yml.sample', 'config/database.yml'
   # end
 
   puts "\n== Preparing database =="
-  system "bin/rake db:setup"
+  system! 'bin/rails db:setup'
 
   puts "\n== Removing old logs and tempfiles =="
-  system "rm -f log/*"
-  system "rm -rf tmp/cache"
+  system! 'bin/rails log:clear tmp:clear'
 
   puts "\n== Restarting application server =="
-  system "touch tmp/restart.txt"
+  system! 'bin/rails restart'
 end
diff --git a/bin/update b/bin/update
new file mode 100755
index 0000000..a8e4462
--- /dev/null
+++ b/bin/update
@@ -0,0 +1,29 @@
+#!/usr/bin/env ruby
+require 'pathname'
+require 'fileutils'
+include FileUtils
+
+# path to your application root.
+APP_ROOT = Pathname.new File.expand_path('../../', __FILE__)
+
+def system!(*args)
+  system(*args) || abort("\n== Command #{args} failed ==")
+end
+
+chdir APP_ROOT do
+  # This script is a way to update your development environment automatically.
+  # Add necessary update steps to this file.
+
+  puts '== Installing dependencies =='
+  system! 'gem install bundler --conservative'
+  system('bundle check') || system!('bundle install')
+
+  puts "\n== Updating database =="
+  system! 'bin/rails db:migrate'
+
+  puts "\n== Removing old logs and tempfiles =="
+  system! 'bin/rails log:clear tmp:clear'
+
+  puts "\n== Restarting application server =="
+  system! 'bin/rails restart'
+end
diff --git a/bin/yarn b/bin/yarn
new file mode 100755
index 0000000..c2bacef
--- /dev/null
+++ b/bin/yarn
@@ -0,0 +1,11 @@
+#!/usr/bin/env ruby
+VENDOR_PATH = File.expand_path('..', __dir__)
+Dir.chdir(VENDOR_PATH) do
+  begin
+    exec "yarnpkg #{ARGV.join(" ")}"
+  rescue Errno::ENOENT
+    $stderr.puts "Yarn executable was not detected in the system."
+    $stderr.puts "Download Yarn at https://yarnpkg.com/en/docs/install"
+    exit 1
+  end
+end
diff --git a/config.ru b/config.ru
index bd83b25..61c04e1 100644
--- a/config.ru
+++ b/config.ru
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This file is used by Rack-based servers to start the application.
 
 require ::File.expand_path('../config/environment', __FILE__)
diff --git a/config/application.rb b/config/application.rb
index 8951f9a..f7afc96 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -1,4 +1,6 @@
-require File.expand_path('../boot', __FILE__)
+# frozen_string_literal: true
+
+require_relative 'boot'
 
 require 'rails/all'
 
@@ -8,19 +10,21 @@
 
 module Conduit
   class Application < Rails::Application
+    # Initialize configuration defaults for originally generated Rails version.
+    config.load_defaults 5.1
+    config.api_only = true
+
     # Settings in config/environments/* take precedence over those specified here.
     # Application configuration should go into files in config/initializers
     # -- all .rb files in that directory are automatically loaded.
+    config.middleware.insert_before 0, Rack::Cors, debug: true, logger: (-> { Rails.logger }) do
+      allow do
+        origins Rails.application.secrets[:client_root_url]
 
-    # Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
-    # Run "rake -D time" for a list of tasks for finding time zone names. Default is UTC.
-    # config.time_zone = 'Central Time (US & Canada)'
-
-    # The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
-    # config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
-    # config.i18n.default_locale = :de
-
-    # Do not swallow errors in after_commit/after_rollback callbacks.
-    config.active_record.raise_in_transactional_callbacks = true
+        resource '/api/*',
+                 headers: :any,
+                 methods: %i[get post delete put patch options head]
+      end
+    end
   end
 end
diff --git a/config/boot.rb b/config/boot.rb
index 6b750f0..30e594e 100644
--- a/config/boot.rb
+++ b/config/boot.rb
@@ -1,3 +1,5 @@
-ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
+# frozen_string_literal: true
+
+ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../Gemfile', __dir__)
 
 require 'bundler/setup' # Set up gems listed in the Gemfile.
diff --git a/config/environment.rb b/config/environment.rb
index ee8d90d..d5abe55 100644
--- a/config/environment.rb
+++ b/config/environment.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 # Load the Rails application.
-require File.expand_path('../application', __FILE__)
+require_relative 'application'
 
 # Initialize the Rails application.
 Rails.application.initialize!
diff --git a/config/environments/development.rb b/config/environments/development.rb
index b55e214..a07ca6d 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
@@ -9,13 +11,28 @@
   # Do not eager load code on boot.
   config.eager_load = false
 
-  # Show full error reports and disable caching.
-  config.consider_all_requests_local       = true
-  config.action_controller.perform_caching = false
+  # Show full error reports.
+  config.consider_all_requests_local = true
+
+  # Enable/disable caching. By default caching is disabled.
+  if Rails.root.join('tmp/caching-dev.txt').exist?
+    config.action_controller.perform_caching = true
+
+    config.cache_store = :memory_store
+    config.public_file_server.headers = {
+      'Cache-Control' => "public, max-age=#{2.days.seconds.to_i}"
+    }
+  else
+    config.action_controller.perform_caching = false
+
+    config.cache_store = :null_store
+  end
 
   # Don't care if the mailer can't send.
   config.action_mailer.raise_delivery_errors = false
 
+  config.action_mailer.perform_caching = false
+
   # Print deprecation notices to the Rails logger.
   config.active_support.deprecation = :log
 
@@ -27,15 +44,15 @@
   # number of complex assets.
   config.assets.debug = true
 
-  # Asset digests allow you to set far-future HTTP expiration dates on all assets,
-  # yet still be able to expire them through the digest params.
-  config.assets.digest = true
-
-  # Adds additional error checking when serving assets at runtime.
-  # Checks for improperly declared sprockets dependencies.
-  # Raises helpful error messages.
-  config.assets.raise_runtime_errors = true
+  # Suppress logger output for asset requests.
+  config.assets.quiet = true
 
   # Raises error for missing translations
   # config.action_view.raise_on_missing_translations = true
+
+  # Use an evented file watcher to asynchronously detect changes in source code,
+  # routes, locales, etc. This feature depends on the listen gem.
+  config.file_watcher = ActiveSupport::EventedFileUpdateChecker
+
+  config.debug_exception_response_format = :default
 end
diff --git a/config/environments/production.rb b/config/environments/production.rb
index 5c1b32e..8a6a409 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
@@ -14,15 +16,14 @@
   config.consider_all_requests_local       = false
   config.action_controller.perform_caching = true
 
-  # Enable Rack::Cache to put a simple HTTP cache in front of your application
-  # Add `rack-cache` to your Gemfile before enabling this.
-  # For large-scale production use, consider using a caching reverse proxy like
-  # NGINX, varnish or squid.
-  # config.action_dispatch.rack_cache = true
+  # Attempt to read encrypted secrets from `config/secrets.yml.enc`.
+  # Requires an encryption key in `ENV["RAILS_MASTER_KEY"]` or
+  # `config/secrets.yml.key`.
+  config.read_encrypted_secrets = true
 
   # Disable serving static files from the `/public` folder by default since
   # Apache or NGINX already handles this.
-  config.serve_static_files = ENV['RAILS_SERVE_STATIC_FILES'].present?
+  config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?
 
   # Compress JavaScripts and CSS.
   config.assets.js_compressor = :uglifier
@@ -31,16 +32,20 @@
   # Do not fallback to assets pipeline if a precompiled asset is missed.
   config.assets.compile = false
 
-  # Asset digests allow you to set far-future HTTP expiration dates on all assets,
-  # yet still be able to expire them through the digest params.
-  config.assets.digest = true
-
   # `config.assets.precompile` and `config.assets.version` have moved to config/initializers/assets.rb
 
+  # Enable serving of images, stylesheets, and JavaScripts from an asset server.
+  # config.action_controller.asset_host = 'http://assets.example.com'
+
   # Specifies the header that your server uses for sending files.
   # config.action_dispatch.x_sendfile_header = 'X-Sendfile' # for Apache
   # config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect' # for NGINX
 
+  # Mount Action Cable outside main process or domain
+  # config.action_cable.mount_path = nil
+  # config.action_cable.url = 'wss://example.com/cable'
+  # config.action_cable.allowed_request_origins = [ 'http://example.com', /http:\/\/example.*/ ]
+
   # Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
   # config.force_ssl = true
 
@@ -49,16 +54,15 @@
   config.log_level = :debug
 
   # Prepend all log lines with the following tags.
-  # config.log_tags = [ :subdomain, :uuid ]
-
-  # Use a different logger for distributed setups.
-  # config.logger = ActiveSupport::TaggedLogging.new(SyslogLogger.new)
+  config.log_tags = [:request_id]
 
   # Use a different cache store in production.
   # config.cache_store = :mem_cache_store
 
-  # Enable serving of images, stylesheets, and JavaScripts from an asset server.
-  # config.action_controller.asset_host = 'http://assets.example.com'
+  # Use a real queuing backend for Active Job (and separate queues per environment)
+  # config.active_job.queue_adapter     = :resque
+  # config.active_job.queue_name_prefix = "conduit_#{Rails.env}"
+  config.action_mailer.perform_caching = false
 
   # Ignore bad email addresses and do not raise email delivery errors.
   # Set this to true and configure the email server for immediate delivery to raise delivery errors.
@@ -74,6 +78,16 @@
   # Use default logging formatter so that PID and timestamp are not suppressed.
   config.log_formatter = ::Logger::Formatter.new
 
+  # Use a different logger for distributed setups.
+  # require 'syslog/logger'
+  # config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new 'app-name')
+
+  if ENV['RAILS_LOG_TO_STDOUT'].present?
+    logger           = ActiveSupport::Logger.new(STDOUT)
+    logger.formatter = config.log_formatter
+    config.logger    = ActiveSupport::TaggedLogging.new(logger)
+  end
+
   # Do not dump schema after migrations.
   config.active_record.dump_schema_after_migration = false
 end
diff --git a/config/environments/test.rb b/config/environments/test.rb
index 1c19f08..669350a 100644
--- a/config/environments/test.rb
+++ b/config/environments/test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
@@ -12,9 +14,11 @@
   # preloads Rails for running tests, you may have to set it to true.
   config.eager_load = false
 
-  # Configure static file server for tests with Cache-Control for performance.
-  config.serve_static_files   = true
-  config.static_cache_control = 'public, max-age=3600'
+  # Configure public file server for tests with Cache-Control for performance.
+  config.public_file_server.enabled = true
+  config.public_file_server.headers = {
+    'Cache-Control' => "public, max-age=#{1.hour.seconds.to_i}"
+  }
 
   # Show full error reports and disable caching.
   config.consider_all_requests_local       = true
@@ -25,15 +29,13 @@
 
   # Disable request forgery protection in test environment.
   config.action_controller.allow_forgery_protection = false
+  config.action_mailer.perform_caching = false
 
   # Tell Action Mailer not to deliver emails to the real world.
   # The :test delivery method accumulates sent emails in the
   # ActionMailer::Base.deliveries array.
   config.action_mailer.delivery_method = :test
 
-  # Randomize the order test cases are executed.
-  config.active_support.test_order = :random
-
   # Print deprecation notices to the stderr.
   config.active_support.deprecation = :stderr
 
diff --git a/config/initializers/application_controller_renderer.rb b/config/initializers/application_controller_renderer.rb
new file mode 100644
index 0000000..315ac48
--- /dev/null
+++ b/config/initializers/application_controller_renderer.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+# Be sure to restart your server when you modify this file.
+
+# ApplicationController.renderer.defaults.merge!(
+#   http_host: 'example.org',
+#   https: false
+# )
diff --git a/config/initializers/assets.rb b/config/initializers/assets.rb
index 01ef3e6..a9b0d0f 100644
--- a/config/initializers/assets.rb
+++ b/config/initializers/assets.rb
@@ -1,11 +1,16 @@
+# frozen_string_literal: true
+
 # Be sure to restart your server when you modify this file.
 
 # Version of your assets, change this if you want to expire all your assets.
 Rails.application.config.assets.version = '1.0'
 
-# Add additional assets to the asset load path
+# Add additional assets to the asset load path.
 # Rails.application.config.assets.paths << Emoji.images_path
+# Add Yarn node_modules folder to the asset load path.
+Rails.application.config.assets.paths << Rails.root.join('node_modules')
 
 # Precompile additional assets.
-# application.js, application.css, and all non-JS/CSS in app/assets folder are already added.
-# Rails.application.config.assets.precompile += %w( search.js )
+# application.js, application.css, and all non-JS/CSS in the app/assets
+# folder are already added.
+# Rails.application.config.assets.precompile += %w( admin.js admin.css )
diff --git a/config/initializers/backtrace_silencers.rb b/config/initializers/backtrace_silencers.rb
index 59385cd..d0f0d3b 100644
--- a/config/initializers/backtrace_silencers.rb
+++ b/config/initializers/backtrace_silencers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # You can add backtrace silencers for libraries that you're using but don't wish to see in your backtraces.
diff --git a/config/initializers/cookies_serializer.rb b/config/initializers/cookies_serializer.rb
index 7f70458..ee8dff9 100644
--- a/config/initializers/cookies_serializer.rb
+++ b/config/initializers/cookies_serializer.rb
@@ -1,3 +1,7 @@
+# frozen_string_literal: true
+
 # Be sure to restart your server when you modify this file.
 
+# Specify a serializer for the signed and encrypted cookie jars.
+# Valid options are :json, :marshal, and :hybrid.
 Rails.application.config.action_dispatch.cookies_serializer = :json
diff --git a/config/initializers/devise.rb b/config/initializers/devise.rb
index 3030731..cf0a4b9 100644
--- a/config/initializers/devise.rb
+++ b/config/initializers/devise.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Use this hook to configure devise mailer, warden hooks and so forth.
 # Many of these configuration options can be set straight in your model.
 Devise.setup do |config|
diff --git a/config/initializers/filter_parameter_logging.rb b/config/initializers/filter_parameter_logging.rb
index 4a994e1..7a4f47b 100644
--- a/config/initializers/filter_parameter_logging.rb
+++ b/config/initializers/filter_parameter_logging.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Be sure to restart your server when you modify this file.
 
 # Configure sensitive parameters which will be filtered from the log file.
diff --git a/config/initializers/inflections.rb b/config/initializers/inflections.rb
index ac033bf..aa7435f 100644
--- a/config/initializers/inflections.rb
+++ b/config/initializers/inflections.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # Add new inflection rules using the following format. Inflections
diff --git a/config/initializers/jbuilder.rb b/config/initializers/jbuilder.rb
index 418045d..b0accfe 100644
--- a/config/initializers/jbuilder.rb
+++ b/config/initializers/jbuilder.rb
@@ -1 +1,3 @@
+# frozen_string_literal: true
+
 Jbuilder.key_format camelize: :lower
diff --git a/config/initializers/json_param_key_transform.rb b/config/initializers/json_param_key_transform.rb
new file mode 100644
index 0000000..4224850
--- /dev/null
+++ b/config/initializers/json_param_key_transform.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+# Transform JSON request param keys from JSON-conventional camelCase to
+# Rails-conventional snake_case:
+ActionDispatch::Request.parameter_parsers[:json] = ->(raw_post) {
+  # Modified from action_dispatch/http/parameters.rb
+  data = ActiveSupport::JSON.decode(raw_post)
+  data = { _json: data } unless data.is_a?(Hash)
+
+  # Transform camelCase param keys to snake_case:
+  data.deep_transform_keys!(&:underscore)
+}
diff --git a/config/initializers/mime_types.rb b/config/initializers/mime_types.rb
index dc18996..6e1d16f 100644
--- a/config/initializers/mime_types.rb
+++ b/config/initializers/mime_types.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Be sure to restart your server when you modify this file.
 
 # Add new mime types for use in respond_to blocks:
diff --git a/config/initializers/new_framework_defaults_5_1.rb b/config/initializers/new_framework_defaults_5_1.rb
new file mode 100644
index 0000000..b33ee80
--- /dev/null
+++ b/config/initializers/new_framework_defaults_5_1.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+# Be sure to restart your server when you modify this file.
+#
+# This file contains migration options to ease your Rails 5.1 upgrade.
+#
+# Once upgraded flip defaults one by one to migrate to the new default.
+#
+# Read the Guide for Upgrading Ruby on Rails for more info on each option.
+
+# Make `form_with` generate non-remote forms.
+Rails.application.config.action_view.form_with_generates_remote_forms = false
+
+# Unknown asset fallback will return the path passed in when the given
+# asset is not present in the asset pipeline.
+# Rails.application.config.assets.unknown_asset_fallback = false
diff --git a/config/initializers/session_store.rb b/config/initializers/session_store.rb
index db7da2a..b788905 100644
--- a/config/initializers/session_store.rb
+++ b/config/initializers/session_store.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Be sure to restart your server when you modify this file.
 
 Rails.application.config.session_store :cookie_store, key: '_conduit_session'
diff --git a/config/initializers/wrap_parameters.rb b/config/initializers/wrap_parameters.rb
index 33725e9..2f3c0db 100644
--- a/config/initializers/wrap_parameters.rb
+++ b/config/initializers/wrap_parameters.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Be sure to restart your server when you modify this file.
 
 # This file contains settings for ActionController::ParamsWrapper which
@@ -5,10 +7,10 @@
 
 # Enable parameter wrapping for JSON. You can disable this by setting :format to an empty array.
 ActiveSupport.on_load(:action_controller) do
-  wrap_parameters format: [:json] if respond_to?(:wrap_parameters)
+  wrap_parameters format: [:json]
 end
 
 # To enable root element in JSON for ActiveRecord objects.
 # ActiveSupport.on_load(:active_record) do
-#  self.include_root_in_json = true
+#   self.include_root_in_json = true
 # end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 0653957..decc5a8 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -16,6 +16,16 @@
 #
 # This would use the information in config/locales/es.yml.
 #
+# The following keys must be escaped otherwise they will not be retrieved by
+# the default I18n backend:
+#
+# true, false, on, off, yes, no
+#
+# Instead, surround them with single quotes.
+#
+# en:
+#   'true': 'foo'
+#
 # To learn more, please read the Rails Internationalization guide
 # available at http://guides.rubyonrails.org/i18n.html.
 
diff --git a/config/locales/responders.en.yml b/config/locales/responders.en.yml
new file mode 100644
index 0000000..c3e147a
--- /dev/null
+++ b/config/locales/responders.en.yml
@@ -0,0 +1,12 @@
+en:
+  flash:
+    actions:
+      create:
+        notice: '%{resource_name} was successfully created.'
+        # alert: '%{resource_name} could not be created.'
+      update:
+        notice: '%{resource_name} was successfully updated.'
+        # alert: '%{resource_name} could not be updated.'
+      destroy:
+        notice: '%{resource_name} was successfully destroyed.'
+        alert: '%{resource_name} could not be destroyed.'
diff --git a/config/puma.rb b/config/puma.rb
new file mode 100644
index 0000000..6ec461f
--- /dev/null
+++ b/config/puma.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+# Puma can serve each request in a thread from an internal thread pool.
+# The `threads` method setting takes two numbers: a minimum and maximum.
+# Any libraries that use thread pools should be configured to match
+# the maximum value specified for Puma. Default is set to 5 threads for minimum
+# and maximum; this matches the default thread size of Active Record.
+#
+threads_count = ENV.fetch('RAILS_MAX_THREADS') { 5 }
+threads threads_count, threads_count
+
+# Specifies the `port` that Puma will listen on to receive requests; default is 3000.
+#
+port        ENV.fetch('PORT') { 3000 }
+
+# Specifies the `environment` that Puma will run in.
+#
+environment ENV.fetch('RAILS_ENV') { 'development' }
+
+# Specifies the number of `workers` to boot in clustered mode.
+# Workers are forked webserver processes. If using threads and workers together
+# the concurrency of the application would be max `threads` * `workers`.
+# Workers do not work on JRuby or Windows (both of which do not support
+# processes).
+#
+# workers ENV.fetch("WEB_CONCURRENCY") { 2 }
+
+# Use the `preload_app!` method when specifying a `workers` number.
+# This directive tells Puma to first boot the application and load code
+# before forking the application. This takes advantage of Copy On Write
+# process behavior so workers use less memory. If you use this option
+# you need to make sure to reconnect any threads in the `on_worker_boot`
+# block.
+#
+# preload_app!
+
+# If you are preloading your application and using Active Record, it's
+# recommended that you close any connections to the database before workers
+# are forked to prevent connection leakage.
+#
+# before_fork do
+#   ActiveRecord::Base.connection_pool.disconnect! if defined?(ActiveRecord)
+# end
+
+# The code in the `on_worker_boot` will be called if you are using
+# clustered mode by specifying a number of `workers`. After each worker
+# process is booted, this block will be run. If you are using the `preload_app!`
+# option, you will want to use this block to reconnect to any threads
+# or connections that may have been created at application boot, as Ruby
+# cannot share connections between processes.
+#
+# on_worker_boot do
+#   ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
+# end
+#
+
+# Allow puma to be restarted by `rails restart` command.
+plugin :tmp_restart
diff --git a/config/routes.rb b/config/routes.rb
index e57aab1..cb76a38 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,18 +1,19 @@
+# frozen_string_literal: true
+
 Rails.application.routes.draw do
   scope :api, defaults: { format: :json } do
     devise_for :users, controllers: { sessions: :sessions },
                        path_names: { sign_in: :login }
 
-
-    resource :user, only: [:show, :update]
+    resource :user, only: %i[show update]
 
     resources :profiles, param: :username, only: [:show] do
-      resource :follow, only: [:create, :destroy]
+      resource :follow, only: %i[create destroy]
     end
 
-    resources :articles, param: :slug, except: [:edit, :new] do
-      resource :favorite, only: [:create, :destroy]
-      resources :comments, only: [:create, :index, :destroy]
+    resources :articles, param: :slug, except: %i[edit new] do
+      resource :favorite, only: %i[create destroy]
+      resources :comments, only: %i[create index destroy]
       get :feed, on: :collection
     end
 
diff --git a/config/secrets.yml b/config/secrets.yml
index 1a49280..565862c 100644
--- a/config/secrets.yml
+++ b/config/secrets.yml
@@ -5,18 +5,20 @@
 
 # Make sure the secret is at least 30 characters and all random,
 # no regular words or you'll be exposed to dictionary attacks.
-# You can use `rake secret` to generate a secure secret key.
+# You can use `rails secret` to generate a secure secret key.
 
 # Make sure the secrets in this file are kept private
 # if you're sharing your code publicly.
 
+# Shared secrets are available across all environments.
+
+shared:
+  client_root_url: http://localhost:4100
+
+# Environmental secrets are only available for that specific environment.
+
 development:
-  secret_key_base: 1cedd34d1be5424c2646c82e267fcbb817dd118d47d52ea8835e7fd8ada93fcec1523148008c0ed647e5f852717692cb0236226929b02c97bfd032a275d5d87a
+  secret_key_base: b4ec4bebe065b6d81ff57acc4c81464d6ce8e8488a67391e0d51f2707ebc4ea474d86fa6c52d22adefd141f7236d6f99da046f4945c4773e6ff5f100eb4f29ed
 
 test:
-  secret_key_base: 7d4d2daa8c4b79efe9a9206d20b877a2cde9c90f46987c6ec24f811d06eddb9d554742fc6c25cd7ec73ce9e698424b152e78bb8bf61da8b669c53677f04ab0b8
-
-# Do not keep production secrets in the repository,
-# instead read values from the environment.
-production:
-  secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>
+  secret_key_base: 25c0c6b3cfc81e9357d13657f5545d3401da7af97a2be88c37c0d5afff8913f49fa2ba5dd75c21fedc8a974e27a8bd486f318510944899eb535175a5359a7277
diff --git a/config/secrets.yml.enc b/config/secrets.yml.enc
new file mode 100644
index 0000000..534adbb
--- /dev/null
+++ b/config/secrets.yml.enc
@@ -0,0 +1 @@
+siBQfbvp2QIrFrw2Nb+S2ZJOKgQrXbV7tHsJWYafnxnruINEIo57G1+KVXIqfTFbvL95wh9R5dKoJj/7iJXk73KUv6VGg2AvmaWU9wEr9/nQsy2ojNAtg6F0T6ImsrzZchRDmycSPQkbQRBeqjDhuHqumSy8sqQOWeeIGM/4A99OxmCQIa2cAoQ09X38Og==--f7rABLaEoAVbrEWg--O15KZL5f10Z882jBsk4udA==
\ No newline at end of file
diff --git a/config/spring.rb b/config/spring.rb
new file mode 100644
index 0000000..c5933e4
--- /dev/null
+++ b/config/spring.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+%w[
+  .ruby-version
+  .rbenv-vars
+  tmp/restart.txt
+  tmp/caching-dev.txt
+].each { |path| Spring.watch(path) }
diff --git a/db/migrate/20160712045707_devise_create_users.rb b/db/migrate/20160712045707_devise_create_users.rb
index 9200e8b..78f4547 100644
--- a/db/migrate/20160712045707_devise_create_users.rb
+++ b/db/migrate/20160712045707_devise_create_users.rb
@@ -1,9 +1,11 @@
-class DeviseCreateUsers < ActiveRecord::Migration
+# frozen_string_literal: true
+
+class DeviseCreateUsers < ActiveRecord::Migration[4.2]
   def change
     create_table :users do |t|
       ## Database authenticatable
-      t.string :email,              null: false, default: ""
-      t.string :encrypted_password, null: false, default: ""
+      t.string :email,              null: false, default: ''
+      t.string :encrypted_password, null: false, default: ''
 
       ## Recoverable
       t.string   :reset_password_token
@@ -30,7 +32,6 @@ def change
       # t.string   :unlock_token # Only if unlock strategy is :email or :both
       # t.datetime :locked_at
 
-
       t.timestamps null: false
     end
 
diff --git a/db/migrate/20160712045739_add_profile_fields_to_users.rb b/db/migrate/20160712045739_add_profile_fields_to_users.rb
index 310bb17..4f02dc5 100644
--- a/db/migrate/20160712045739_add_profile_fields_to_users.rb
+++ b/db/migrate/20160712045739_add_profile_fields_to_users.rb
@@ -1,4 +1,6 @@
-class AddProfileFieldsToUsers < ActiveRecord::Migration
+# frozen_string_literal: true
+
+class AddProfileFieldsToUsers < ActiveRecord::Migration[4.2]
   def change
     add_column :users, :username, :string
     add_index :users, :username, unique: true
diff --git a/db/migrate/20160712052128_create_articles.rb b/db/migrate/20160712052128_create_articles.rb
index afde63d..390e624 100644
--- a/db/migrate/20160712052128_create_articles.rb
+++ b/db/migrate/20160712052128_create_articles.rb
@@ -1,4 +1,6 @@
-class CreateArticles < ActiveRecord::Migration
+# frozen_string_literal: true
+
+class CreateArticles < ActiveRecord::Migration[4.2]
   def change
     create_table :articles do |t|
       t.string :title
diff --git a/db/migrate/20160712054809_acts_as_taggable_on_migration.acts_as_taggable_on_engine.rb b/db/migrate/20160712054809_acts_as_taggable_on_migration.acts_as_taggable_on_engine.rb
index 6bbd559..ec6c394 100644
--- a/db/migrate/20160712054809_acts_as_taggable_on_migration.acts_as_taggable_on_engine.rb
+++ b/db/migrate/20160712054809_acts_as_taggable_on_migration.acts_as_taggable_on_engine.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 # This migration comes from acts_as_taggable_on_engine (originally 1)
-class ActsAsTaggableOnMigration < ActiveRecord::Migration
+class ActsAsTaggableOnMigration < ActiveRecord::Migration[4.2]
   def self.up
     create_table :tags do |t|
       t.string :name
@@ -21,7 +23,7 @@ def self.up
     end
 
     add_index :taggings, :tag_id
-    add_index :taggings, [:taggable_id, :taggable_type, :context]
+    add_index :taggings, %i[taggable_id taggable_type context]
   end
 
   def self.down
diff --git a/db/migrate/20160712054810_add_missing_unique_indices.acts_as_taggable_on_engine.rb b/db/migrate/20160712054810_add_missing_unique_indices.acts_as_taggable_on_engine.rb
index 4ca676f..34e5f54 100644
--- a/db/migrate/20160712054810_add_missing_unique_indices.acts_as_taggable_on_engine.rb
+++ b/db/migrate/20160712054810_add_missing_unique_indices.acts_as_taggable_on_engine.rb
@@ -1,12 +1,14 @@
+# frozen_string_literal: true
+
 # This migration comes from acts_as_taggable_on_engine (originally 2)
-class AddMissingUniqueIndices < ActiveRecord::Migration
+class AddMissingUniqueIndices < ActiveRecord::Migration[4.2]
   def self.up
     add_index :tags, :name, unique: true
 
     remove_index :taggings, :tag_id
-    remove_index :taggings, [:taggable_id, :taggable_type, :context]
+    remove_index :taggings, %i[taggable_id taggable_type context]
     add_index :taggings,
-              [:tag_id, :taggable_id, :taggable_type, :context, :tagger_id, :tagger_type],
+              %i[tag_id taggable_id taggable_type context tagger_id tagger_type],
               unique: true, name: 'taggings_idx'
   end
 
@@ -15,6 +17,6 @@ def self.down
 
     remove_index :taggings, name: 'taggings_idx'
     add_index :taggings, :tag_id
-    add_index :taggings, [:taggable_id, :taggable_type, :context]
+    add_index :taggings, %i[taggable_id taggable_type context]
   end
 end
diff --git a/db/migrate/20160712054811_add_taggings_counter_cache_to_tags.acts_as_taggable_on_engine.rb b/db/migrate/20160712054811_add_taggings_counter_cache_to_tags.acts_as_taggable_on_engine.rb
index 8edb508..e4bdc65 100644
--- a/db/migrate/20160712054811_add_taggings_counter_cache_to_tags.acts_as_taggable_on_engine.rb
+++ b/db/migrate/20160712054811_add_taggings_counter_cache_to_tags.acts_as_taggable_on_engine.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 # This migration comes from acts_as_taggable_on_engine (originally 3)
-class AddTaggingsCounterCacheToTags < ActiveRecord::Migration
+class AddTaggingsCounterCacheToTags < ActiveRecord::Migration[4.2]
   def self.up
     add_column :tags, :taggings_count, :integer, default: 0
 
diff --git a/db/migrate/20160712054812_add_missing_taggable_index.acts_as_taggable_on_engine.rb b/db/migrate/20160712054812_add_missing_taggable_index.acts_as_taggable_on_engine.rb
index 71f2d7f..c6cd136 100644
--- a/db/migrate/20160712054812_add_missing_taggable_index.acts_as_taggable_on_engine.rb
+++ b/db/migrate/20160712054812_add_missing_taggable_index.acts_as_taggable_on_engine.rb
@@ -1,10 +1,12 @@
+# frozen_string_literal: true
+
 # This migration comes from acts_as_taggable_on_engine (originally 4)
-class AddMissingTaggableIndex < ActiveRecord::Migration
+class AddMissingTaggableIndex < ActiveRecord::Migration[4.2]
   def self.up
-    add_index :taggings, [:taggable_id, :taggable_type, :context]
+    add_index :taggings, %i[taggable_id taggable_type context]
   end
 
   def self.down
-    remove_index :taggings, [:taggable_id, :taggable_type, :context]
+    remove_index :taggings, %i[taggable_id taggable_type context]
   end
 end
diff --git a/db/migrate/20160712054813_change_collation_for_tag_names.acts_as_taggable_on_engine.rb b/db/migrate/20160712054813_change_collation_for_tag_names.acts_as_taggable_on_engine.rb
index bfb06bc..d8eac54 100644
--- a/db/migrate/20160712054813_change_collation_for_tag_names.acts_as_taggable_on_engine.rb
+++ b/db/migrate/20160712054813_change_collation_for_tag_names.acts_as_taggable_on_engine.rb
@@ -1,10 +1,12 @@
+# frozen_string_literal: true
+
 # This migration comes from acts_as_taggable_on_engine (originally 5)
 # This migration is added to circumvent issue #623 and have special characters
 # work properly
-class ChangeCollationForTagNames < ActiveRecord::Migration
+class ChangeCollationForTagNames < ActiveRecord::Migration[4.2]
   def up
     if ActsAsTaggableOn::Utils.using_mysql?
-      execute("ALTER TABLE tags MODIFY name varchar(255) CHARACTER SET utf8 COLLATE utf8_bin;")
+      execute('ALTER TABLE tags MODIFY name varchar(255) CHARACTER SET utf8 COLLATE utf8_bin;')
     end
   end
 end
diff --git a/db/migrate/20160712055201_create_favorites.rb b/db/migrate/20160712055201_create_favorites.rb
index f754e99..39cc68f 100644
--- a/db/migrate/20160712055201_create_favorites.rb
+++ b/db/migrate/20160712055201_create_favorites.rb
@@ -1,4 +1,6 @@
-class CreateFavorites < ActiveRecord::Migration
+# frozen_string_literal: true
+
+class CreateFavorites < ActiveRecord::Migration[4.2]
   def change
     create_table :favorites do |t|
       t.references :user, index: true, foreign_key: true
diff --git a/db/migrate/20160712061113_create_comments.rb b/db/migrate/20160712061113_create_comments.rb
index f015006..488d8c3 100644
--- a/db/migrate/20160712061113_create_comments.rb
+++ b/db/migrate/20160712061113_create_comments.rb
@@ -1,4 +1,6 @@
-class CreateComments < ActiveRecord::Migration
+# frozen_string_literal: true
+
+class CreateComments < ActiveRecord::Migration[4.2]
   def change
     create_table :comments do |t|
       t.text :body
diff --git a/db/migrate/20160712061614_acts_as_follower_migration.rb b/db/migrate/20160712061614_acts_as_follower_migration.rb
index 0b39c01..9157184 100644
--- a/db/migrate/20160712061614_acts_as_follower_migration.rb
+++ b/db/migrate/20160712061614_acts_as_follower_migration.rb
@@ -1,4 +1,6 @@
-class ActsAsFollowerMigration < ActiveRecord::Migration
+# frozen_string_literal: true
+
+class ActsAsFollowerMigration < ActiveRecord::Migration[4.2]
   def self.up
     create_table :follows, force: true do |t|
       t.references :followable, polymorphic: true, null: false
@@ -7,8 +9,8 @@ def self.up
       t.timestamps
     end
 
-    add_index :follows, ["follower_id", "follower_type"],     name: "fk_follows"
-    add_index :follows, ["followable_id", "followable_type"], name: "fk_followables"
+    add_index :follows, %w[follower_id follower_type],     name: 'fk_follows'
+    add_index :follows, %w[followable_id followable_type], name: 'fk_followables'
   end
 
   def self.down
diff --git a/db/migrate/20181015165120_add_missing_indexes_on_taggings.acts_as_taggable_on_engine.rb b/db/migrate/20181015165120_add_missing_indexes_on_taggings.acts_as_taggable_on_engine.rb
new file mode 100644
index 0000000..7416261
--- /dev/null
+++ b/db/migrate/20181015165120_add_missing_indexes_on_taggings.acts_as_taggable_on_engine.rb
@@ -0,0 +1,18 @@
+# This migration comes from acts_as_taggable_on_engine (originally 6)
+class AddMissingIndexesOnTaggings < ActiveRecord::Migration[4.2]
+  def change
+    add_index :taggings, :tag_id unless index_exists? :taggings, :tag_id
+    add_index :taggings, :taggable_id unless index_exists? :taggings, :taggable_id
+    add_index :taggings, :taggable_type unless index_exists? :taggings, :taggable_type
+    add_index :taggings, :tagger_id unless index_exists? :taggings, :tagger_id
+    add_index :taggings, :context unless index_exists? :taggings, :context
+
+    unless index_exists? :taggings, [:tagger_id, :tagger_type]
+      add_index :taggings, [:tagger_id, :tagger_type]
+    end
+
+    unless index_exists? :taggings, [:taggable_id, :taggable_type, :tagger_id, :context], name: 'taggings_idy'
+      add_index :taggings, [:taggable_id, :taggable_type, :tagger_id, :context], name: 'taggings_idy'
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index c65c025..29be70a 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -1,4 +1,3 @@
-# encoding: UTF-8
 # This file is auto-generated from the current state of the database. Instead
 # of editing this file, please use the migrations feature of Active Record to
 # incrementally modify your database, and then regenerate this schema definition.
@@ -11,96 +10,96 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160712061614) do
+ActiveRecord::Schema.define(version: 20181015165120) do
 
   create_table "articles", force: :cascade do |t|
-    t.string   "title"
-    t.string   "slug"
-    t.text     "body"
-    t.string   "description"
-    t.integer  "favorites_count"
-    t.integer  "user_id"
-    t.datetime "created_at",      null: false
-    t.datetime "updated_at",      null: false
+    t.string "title"
+    t.string "slug"
+    t.text "body"
+    t.string "description"
+    t.integer "favorites_count"
+    t.integer "user_id"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["slug"], name: "index_articles_on_slug", unique: true
+    t.index ["user_id"], name: "index_articles_on_user_id"
   end
 
-  add_index "articles", ["slug"], name: "index_articles_on_slug", unique: true
-  add_index "articles", ["user_id"], name: "index_articles_on_user_id"
-
   create_table "comments", force: :cascade do |t|
-    t.text     "body"
-    t.integer  "user_id"
-    t.integer  "article_id"
+    t.text "body"
+    t.integer "user_id"
+    t.integer "article_id"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.index ["article_id"], name: "index_comments_on_article_id"
+    t.index ["user_id"], name: "index_comments_on_user_id"
   end
 
-  add_index "comments", ["article_id"], name: "index_comments_on_article_id"
-  add_index "comments", ["user_id"], name: "index_comments_on_user_id"
-
   create_table "favorites", force: :cascade do |t|
-    t.integer  "user_id"
-    t.integer  "article_id"
+    t.integer "user_id"
+    t.integer "article_id"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.index ["article_id"], name: "index_favorites_on_article_id"
+    t.index ["user_id"], name: "index_favorites_on_user_id"
   end
 
-  add_index "favorites", ["article_id"], name: "index_favorites_on_article_id"
-  add_index "favorites", ["user_id"], name: "index_favorites_on_user_id"
-
   create_table "follows", force: :cascade do |t|
-    t.integer  "followable_id",                   null: false
-    t.string   "followable_type",                 null: false
-    t.integer  "follower_id",                     null: false
-    t.string   "follower_type",                   null: false
-    t.boolean  "blocked",         default: false, null: false
+    t.string "followable_type", null: false
+    t.integer "followable_id", null: false
+    t.string "follower_type", null: false
+    t.integer "follower_id", null: false
+    t.boolean "blocked", default: false, null: false
     t.datetime "created_at"
     t.datetime "updated_at"
+    t.index ["followable_id", "followable_type"], name: "fk_followables"
+    t.index ["follower_id", "follower_type"], name: "fk_follows"
   end
 
-  add_index "follows", ["followable_id", "followable_type"], name: "fk_followables"
-  add_index "follows", ["follower_id", "follower_type"], name: "fk_follows"
-
   create_table "taggings", force: :cascade do |t|
-    t.integer  "tag_id"
-    t.integer  "taggable_id"
-    t.string   "taggable_type"
-    t.integer  "tagger_id"
-    t.string   "tagger_type"
-    t.string   "context",       limit: 128
+    t.integer "tag_id"
+    t.string "taggable_type"
+    t.integer "taggable_id"
+    t.string "tagger_type"
+    t.integer "tagger_id"
+    t.string "context", limit: 128
     t.datetime "created_at"
+    t.index ["context"], name: "index_taggings_on_context"
+    t.index ["tag_id", "taggable_id", "taggable_type", "context", "tagger_id", "tagger_type"], name: "taggings_idx", unique: true
+    t.index ["tag_id"], name: "index_taggings_on_tag_id"
+    t.index ["taggable_id", "taggable_type", "context"], name: "index_taggings_on_taggable_id_and_taggable_type_and_context"
+    t.index ["taggable_id", "taggable_type", "tagger_id", "context"], name: "taggings_idy"
+    t.index ["taggable_id"], name: "index_taggings_on_taggable_id"
+    t.index ["taggable_type"], name: "index_taggings_on_taggable_type"
+    t.index ["tagger_id", "tagger_type"], name: "index_taggings_on_tagger_id_and_tagger_type"
+    t.index ["tagger_id"], name: "index_taggings_on_tagger_id"
   end
 
-  add_index "taggings", ["tag_id", "taggable_id", "taggable_type", "context", "tagger_id", "tagger_type"], name: "taggings_idx", unique: true
-  add_index "taggings", ["taggable_id", "taggable_type", "context"], name: "index_taggings_on_taggable_id_and_taggable_type_and_context"
-
   create_table "tags", force: :cascade do |t|
-    t.string  "name"
+    t.string "name"
     t.integer "taggings_count", default: 0
+    t.index ["name"], name: "index_tags_on_name", unique: true
   end
 
-  add_index "tags", ["name"], name: "index_tags_on_name", unique: true
-
   create_table "users", force: :cascade do |t|
-    t.string   "email",                  default: "", null: false
-    t.string   "encrypted_password",     default: "", null: false
-    t.string   "reset_password_token"
+    t.string "email", default: "", null: false
+    t.string "encrypted_password", default: "", null: false
+    t.string "reset_password_token"
     t.datetime "reset_password_sent_at"
     t.datetime "remember_created_at"
-    t.integer  "sign_in_count",          default: 0,  null: false
+    t.integer "sign_in_count", default: 0, null: false
     t.datetime "current_sign_in_at"
     t.datetime "last_sign_in_at"
-    t.string   "current_sign_in_ip"
-    t.string   "last_sign_in_ip"
-    t.datetime "created_at",                          null: false
-    t.datetime "updated_at",                          null: false
-    t.string   "username"
-    t.string   "image"
-    t.text     "bio"
+    t.string "current_sign_in_ip"
+    t.string "last_sign_in_ip"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.string "username"
+    t.string "image"
+    t.text "bio"
+    t.index ["email"], name: "index_users_on_email", unique: true
+    t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
+    t.index ["username"], name: "index_users_on_username", unique: true
   end
 
-  add_index "users", ["email"], name: "index_users_on_email", unique: true
-  add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
-  add_index "users", ["username"], name: "index_users_on_username", unique: true
-
 end
diff --git a/test/controllers/articles_controller_test.rb b/test/controllers/articles_controller_test.rb
new file mode 100644
index 0000000..d873d68
--- /dev/null
+++ b/test/controllers/articles_controller_test.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ArticlesControllerTest < ActionDispatch::IntegrationTest
+  # test "the truth" do
+  #   assert true
+  # end
+end
diff --git a/test/models/article_test.rb b/test/models/article_test.rb
index 11c8abe..cfa5eba 100644
--- a/test/models/article_test.rb
+++ b/test/models/article_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class ArticleTest < ActiveSupport::TestCase
diff --git a/test/models/comment_test.rb b/test/models/comment_test.rb
index b6d6131..7a6452f 100644
--- a/test/models/comment_test.rb
+++ b/test/models/comment_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class CommentTest < ActiveSupport::TestCase
diff --git a/test/models/favorite_test.rb b/test/models/favorite_test.rb
index 1cc6656..84a2080 100644
--- a/test/models/favorite_test.rb
+++ b/test/models/favorite_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class FavoriteTest < ActiveSupport::TestCase
diff --git a/test/models/user_test.rb b/test/models/user_test.rb
index 82f61e0..5cc44ed 100644
--- a/test/models/user_test.rb
+++ b/test/models/user_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class UserTest < ActiveSupport::TestCase
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 92e39b2..c5369ca 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 ENV['RAILS_ENV'] ||= 'test'
 require File.expand_path('../../config/environment', __FILE__)
 require 'rails/test_help'