Expose rubygem reverse depencencies

app/controllers/concerns/latest_version.rb

@@ -0,0 +1,9 @@
+module LatestVersion
+  extend ActiveSupport::Concern
+
+  included do
+    def latest_version
+      @latest_version ||= @rubygem.versions.most_recent
+    end
+  end
+end

app/controllers/reverse_dependencies_controller.rb

@@ -0,0 +1,16 @@
+class ReverseDependenciesController < ApplicationController
+  include LatestVersion
+  before_action :find_rubygem, only: [:index]
+  before_action :latest_version, only: [:index]
+  before_action :set_page, only: [:index]
+
+  def index
+    @reverse_dependencies = @rubygem.reverse_dependencies
+      .by_downloads
+      .includes(:latest_version, :gem_download)
+    if params[:rdeps_query] && params[:rdeps_query].is_a?(String)
+      @reverse_dependencies = @reverse_dependencies.search(params[:rdeps_query])
+    end
+    @reverse_dependencies = @reverse_dependencies.paginate(page: @page)
+  end
+end

app/controllers/rubygems_controller.rb

@@ -1,7 +1,9 @@
 class RubygemsController < ApplicationController
+  include LatestVersion
   before_action :redirect_to_root, only: [:edit, :update], unless: :signed_in?
   before_action :set_blacklisted_gem, only: [:show], if: :blacklisted?
   before_action :find_rubygem, only: [:edit, :update, :show], unless: :blacklisted?
+  before_action :latest_version, only: [:show], unless: :blacklisted?
   before_action :load_gem, only: [:edit, :update]
   before_action :set_page, only: :index
 
@@ -22,8 +24,7 @@ def show
     if @blacklisted_gem
       render 'blacklisted'
     else
-      @latest_version = @rubygem.versions.most_recent
-      @versions       = @rubygem.public_versions(5)
+      @versions = @rubygem.public_versions(5)
       if @rubygem.public_versions.any?
         render 'show'
       else

app/helpers/rubygems_helper.rb

@@ -76,6 +76,10 @@ def download_link(version)
     link_to_page :download, "/downloads/#{version.full_name}.gem"
   end
 
+  def reverse_dependencies_link(rubygem)
+    link_to_page :reverse_dependencies, rubygem_reverse_dependencies_path(rubygem)
+  end
+
   def documentation_link(version, linkset)
     return unless linkset.nil? || linkset.docs.blank?
     link_to_page :docs, version.documentation_path

app/models/rubygem.rb

@@ -269,6 +269,10 @@ def protected_days
     (updated_at + 101.days - Time.zone.now).to_i / 1.day
   end
 
+  def reverse_dependencies
+    self.class.reverse_dependencies(name)
+  end
+
   private
 
   # a gem namespace is not protected if it is

app/views/reverse_dependencies/_reverse_dependencies.html.erb

@@ -0,0 +1,12 @@
+<header class="gems__header push">
+  <%= form_tag rubygem_reverse_dependencies_path(@rubygem),
+    id: "rdeps-search", class: "header__search-wrap", method: :get do %>
+    <%= search_field_tag :rdeps_query, params[:rdeps_query], placeholder: t('.search_reverse_dependencies').html_safe, class: "header__search" %>
+    <%= label_tag :rdeps_query do %>
+      <span class="t-hidden"><%= t('.search_reverse_dependencies').html_safe %></span>
+    <% end %>
+    <%= submit_tag '⌕', id: 'rdeps_search_submit', name: nil, class: "header__search__icon" %>
+  <% end %>
+</header>
+
+<%= render dependencies %>

app/views/reverse_dependencies/index.html.erb

@@ -0,0 +1,11 @@
+<% @title = t('.title', name: @rubygem.name) %>
+<% @subtitle = @latest_version.try(:slug) %>
+
+<div class="l-overflow">
+  <div class="l-colspan--l colspan--l--has-border">
+    <%= render partial: "reverse_dependencies",
+      locals: { dependencies: @reverse_dependencies } %>
+    <%= will_paginate @reverse_dependencies %>
+  </div>
+  <%= render 'rubygems/aside' %>
+</div>

app/views/rubygems/_aside.html.erb

@@ -77,5 +77,6 @@
     <%= unsubscribe_link(@rubygem) %>
     <%= atom_link(@rubygem) %>
     <%= report_abuse_link(@rubygem) %>
+    <%= reverse_dependencies_link(@rubygem) %>
   </div>
 </div>

config/locales/en.yml

@@ -149,6 +149,7 @@ en:
         report_abuse: Report Abuse
         badge: Badge
         rss: RSS
+        reverse_dependencies: Reverse dependencies
       downloads_for_this_version: "For this version"
       bundler_header: Gemfile
       copy_to_clipboard: Copy to clipboard
@@ -164,6 +165,12 @@ en:
       no_licenses: N/A
       requirements_header: Requirements
 
+  reverse_dependencies:
+    index:
+      title: "Reverse dependencies for %{name}"
+    reverse_dependencies:
+      search_reverse_dependencies: "Search reverse dependencies Gems…"
+
   searches:
     show:
       subtitle: "for %{query}"

config/routes.rb

@@ -139,6 +139,7 @@
         constraints: { format: :js },
         defaults: { format: :js }
       resources :versions, only: [:show, :index]
+      resources :reverse_dependencies, only: [:index]
     end
   end
 

test/functional/reverse_dependencies_controller_test.rb

@@ -0,0 +1,53 @@
+require 'test_helper'
+
+class ReverseDependenciesControllerTest < ActionController::TestCase
+  context "On GET to show for a gem reverse dependencies" do
+    setup do
+      @version_one = create(:version)
+      @rubygem_one = @version_one.rubygem
+      @version_two = create(:version)
+      @rubygem_two = @version_two.rubygem
+      @version_three = create(:version)
+      @rubygem_three = @version_three.rubygem
+      @version_four = create(:version)
+      @rubygem_four = @version_four.rubygem
+
+      @version_two.dependencies << create(:dependency,
+        version: @version_two,
+        rubygem: @rubygem_one)
+      @version_three.dependencies << create(:dependency,
+        version: @version_three,
+        rubygem: @rubygem_two)
+      @version_four.dependencies << create(:dependency,
+        version: @version_four,
+        rubygem: @rubygem_two)
+    end
+
+    should "render template" do
+      get :index, rubygem_id: @rubygem_one.to_param
+      respond_with :success
+      render_template :index
+    end
+
+    should "show reverse dependencies" do
+      get :index, rubygem_id: @rubygem_one.to_param
+      assert page.has_content?(@rubygem_two.name)
+      refute page.has_content?(@rubygem_three.name)
+    end
+
+    should "search reverse dependencies" do
+      get :index,
+        rubygem_id: @rubygem_two.to_param,
+        rdeps_query: @rubygem_three.name
+      assert page.has_content?(@rubygem_three.name)
+      refute page.has_content?(@rubygem_four.name)
+    end
+
+    should "search only current reverse dependencies" do
+      get :index,
+        rubygem_id: @rubygem_two.to_param,
+        rdeps_query: @rubygem_one.name
+      refute page.has_content?(@rubygem_one.name)
+    end
+  end
+end