Add Issuable#to_ability_name

app/models/concerns/issuable.rb

@@ -159,6 +159,16 @@ module Issuable
     end
   end
 
+  # Convert this Issuable class name to a format usable by Ability definitions
+  #
+  # Examples:
+  #
+  #   issuable.class           # => MergeRequest
+  #   issuable.to_ability_name # => "merge_request"
+  def to_ability_name
+    self.class.to_s.underscore
+  end
+
   private
 
   def filter_superceded_votes(votes, notes)

app/views/shared/issuable/_context.html.haml

@@ -8,7 +8,7 @@
       - else
         none
     .issuable-context-selectbox
-      - if can?(current_user, :"admin_#{issuable.class.to_s.underscore}", @project)
+      - if can?(current_user, :"admin_#{issuable.to_ability_name}", @project)
         = users_select_tag("#{issuable.class.table_name.singularize}[assignee_id]", placeholder: 'Select assignee', class: 'custom-form-control js-select2 js-assignee', selected: issuable.assignee_id, project: @target_project, null_user: true)
 
   %div.prepend-top-20.clearfix
@@ -24,7 +24,7 @@
       - else
         none
     .issuable-context-selectbox
-      - if can?(current_user, :"admin_#{issuable.class.to_s.underscore}", @project)
+      - if can?(current_user, :"admin_#{issuable.to_ability_name}", @project)
         = f.select(:milestone_id, milestone_options(issuable), { include_blank: 'Select milestone' }, {class: 'select2 select2-compact js-select2 js-milestone'})
         = hidden_field_tag :issuable_context
         = f.submit class: 'btn hide'