Show checkbox on pd declaration page

app/views/accounts/pd_declarations/show.html.erb

@@ -1,3 +1,11 @@
 <% content_for :heading do %>
   <h1><%= t ".title" %></h1>
 <% end %>
+
+<%= bootstrap_form_tag do |f| %>
+  <%= f.check_box :consider_pd,
+                  :label => t(".consider_pd"),
+                  :autocomplete => :off,
+                  :checked => current_user.consider_pd,
+                  :disabled => current_user.consider_pd %>
+<% end %>

config/locales/en.yml

@@ -327,6 +327,7 @@ en:
     pd_declarations:
       show:
         title: Consider my contributions to be in the Public Domain
+        consider_pd: "I consider my contributions to be in the Public Domain"
   browse:
     deleted_ago_by_html: "Deleted %{time_ago} by %{user}"
     edited_ago_by_html: "Edited %{time_ago} by %{user}"

test/system/account_pd_declaration_test.rb

@@ -0,0 +1,26 @@
+require "application_system_test_case"
+
+class AccountPdDeclarationTest < ApplicationSystemTestCase
+  def setup
+    @user = create(:user, :display_name => "test user")
+    sign_in_as(@user)
+  end
+
+  test "show checkbox if no declaration was made" do
+    visit account_pd_declaration_path
+
+    within_content_body do
+      assert_unchecked_field "I consider my contributions to be in the Public Domain"
+    end
+  end
+
+  test "show disabled checkbox if declaration was made" do
+    @user.update(:consider_pd => true)
+
+    visit account_pd_declaration_path
+
+    within_content_body do
+      assert_checked_field "I consider my contributions to be in the Public Domain", :disabled => true
+    end
+  end
+end