Add readme only option as project view

app/helpers/preferences_helper.rb

@@ -36,7 +36,8 @@ module PreferencesHelper
   def project_view_choices
     [
       ['Files and Readme (default)', :files],
-      ['Activity', :activity]
+      ['Activity', :activity],
+      ['Readme', :readme]
     ]
   end

app/models/user.rb

@@ -182,13 +182,9 @@ class User < ActiveRecord::Base
   enum dashboard: [:projects, :stars, :project_activity, :starred_project_activity, :groups, :todos]
   # User's Project preference
-  #
-  # Note: When adding an option, it MUST go on the end of the hash with a
-  # number higher than the current max. We cannot move options and/or change
-  # their numbers.
-  #
-  # We skip 0 because this was used by an option that has since been removed.
-  enum project_view: { activity: 1, files: 2 }
+  # Note: When adding an option, it MUST go on the end of the array.
+  enum project_view: [:readme, :activity, :files]
+
   alias_attribute :private_token, :authentication_token

app/views/projects/_readme.html.haml

+- if readme = @repository.readme
+  %article.file-holder.readme-holder{ id: 'readme', class: ("limited-width-container" unless fluid_layout) }
+    = render 'projects/blob/viewer', viewer: readme.rich_viewer, viewer_url: namespace_project_blob_path(@project.namespace, @project, tree_join(@repository.root_ref, readme.path), viewer: :rich, format: :json)
+
+- else
+  .row-content-block.second-block.center
+    %h3.page-title
+      This project does not have a README yet
+    - if can?(current_user, :push_code, @project)
+      %p
+        A
+        %code README
+        file contains information about other files in a repository and is commonly
+        distributed with computer software, forming part of its documentation.
+      %p
+        We recommend you to
+        = link_to "add a README", add_special_file_path(@project, file_name: 'README.md'), class: 'underlined-link'
+        file to the repository and GitLab will render it here instead of this message.

changelogs/unreleased/30140-restore-readme-only-preference.yml

+---
+title: Add readme only option as project view
+merge_request: 14900
+author:
+type: changed

spec/controllers/projects_controller_spec.rb

@@ -222,6 +222,14 @@ describe ProjectsController do
         get :show, namespace_id: public_project.namespace, id: public_project
         expect(response).to render_template('_files')
       end
+
+      it "renders the readme view" do
+        allow(controller).to receive(:current_user).and_return(user)
+        allow(user).to receive(:project_view).and_return('readme')
+
+        get :show, namespace_id: public_project.namespace, id: public_project
+        expect(response).to render_template('_readme')
+      end
     end
     context "when the url contains .atom" do

spec/migrations/migrate_user_project_view_spec.rb

@@ -5,12 +5,7 @@ require Rails.root.join('db', 'post_migrate', '20170406142253_migrate_user_proje
 describe MigrateUserProjectView, :truncate do
   let(:migration) { described_class.new }
-  let!(:user) { create(:user) }
-
-  before do
-    # 0 is the numeric value for the old 'readme' option
-    user.update_column(:project_view, 0)
-  end
+  let!(:user) { create(:user, project_view: 'readme') }
   describe '#up' do
     it 'updates project view setting with new value' do