FIX: topics tagged with muted tags should not be included in digest emails

app/models/topic.rb

@@ -361,6 +361,13 @@ class Topic < ActiveRecord::Base
       topics = topics.where("topics.category_id NOT IN (?)", muted_category_ids)
     end
 
+    # Remove muted categories
+    muted_tag_ids = TagUser.lookup(user, :muted).pluck(:tag_id)
+    unless muted_tag_ids.empty?
+      topics = topics.joins("LEFT OUTER JOIN topic_tags ON topic_tags.topic_id = topics.id")
+                     .where("topic_tags.tag_id NOT IN (?)", muted_tag_ids)
+    end
+
     topics
   end
 

spec/models/topic_spec.rb

@@ -1364,6 +1364,24 @@ describe Topic do
       expect(Topic.for_digest(u, 1.year.ago, top_order: true)).to eq([topic])
     end
 
+    it "doesn't return topics with only muted tags" do
+      user = Fabricate(:user)
+      tag = Fabricate(:tag)
+      TagUser.change(user.id, tag.id, TagUser.notification_levels[:muted])
+      topic = Fabricate(:topic, tags: [tag])
+
+      expect(Topic.for_digest(user, 1.year.ago, top_order: true)).to be_blank
+    end
+
+    it "returns topics with both muted and not muted tags" do
+      user = Fabricate(:user)
+      muted_tag, other_tag = Fabricate(:tag), Fabricate(:tag)
+      TagUser.change(user.id, muted_tag.id, TagUser.notification_levels[:muted])
+      topic = Fabricate(:topic, tags: [muted_tag, other_tag])
+
+      expect(Topic.for_digest(user, 1.year.ago, top_order: true)).to eq([topic])
+    end
+
   end
 
   describe 'secured' do