FIX: when searching PMs also search group PMs

Users belonging to a group could not search for PMs unless explicitly added
to the PM unless admin

app/models/post.rb

@@ -59,6 +59,18 @@ class Post < ActiveRecord::Base
 
   SHORT_POST_CHARS = 1200
 
+  scope :private_posts_for_user, ->(user) {
+    where("posts.topic_id IN (SELECT topic_id
+             FROM topic_allowed_users
+             WHERE user_id = :user_id
+             UNION ALL
+             SELECT tg.topic_id
+             FROM topic_allowed_groups tg
+             JOIN group_users gu ON gu.user_id = :user_id AND
+                                      gu.group_id = tg.group_id)",
+                                              user_id: user.id)
+  }
+
   scope :by_newest, -> { order('created_at desc, id desc') }
   scope :by_post_number, -> { order('post_number ASC') }
   scope :with_user, -> { includes(:user) }

lib/search.rb

@@ -610,7 +610,7 @@ class Search
          posts = posts.where("topics.archetype =  ?", Archetype.private_message)
 
          unless @guardian.is_admin?
-            posts = posts.where("topics.id IN (SELECT topic_id FROM topic_allowed_users WHERE user_id = ?)", @guardian.user.id)
+           posts = posts.private_posts_for_user(@guardian.user)
          end
       else
          posts = posts.where("topics.archetype <> ?", Archetype.private_message)
@@ -654,15 +654,7 @@ class Search
         if @search_context.is_a?(User)
 
           if opts[:private_messages]
-            posts = posts.where("topics.id IN (SELECT topic_id
-                                               FROM topic_allowed_users
-                                               WHERE user_id = :user_id
-                                               UNION ALL
-                                               SELECT tg.topic_id
-                                               FROM topic_allowed_groups tg
-                                               JOIN group_users gu ON gu.user_id = :user_id AND
-                                                                        gu.group_id = tg.group_id)",
-                                              user_id: @search_context.id)
+            posts = posts.private_posts_for_user(@search_context)
           else
             posts = posts.where("posts.user_id = #{@search_context.id}")
           end

spec/components/search_spec.rb

@@ -204,6 +204,20 @@ describe Search do
 
       expect(results.posts.length).to eq(1)
 
+      # can search group PMs as well as non admin
+      #
+      user = Fabricate(:user)
+      group = Fabricate.build(:group)
+      group.add(user)
+      group.save!
+
+      TopicAllowedGroup.create!(group_id: group.id, topic_id: topic.id)
+
+      results = Search.execute('mars in:private',
+                              guardian: Guardian.new(user))
+
+      expect(results.posts.length).to eq(1)
+
     end
 
   end