FEATURE: hide muted categories from /categories list (#6531)

app/models/category_list.rb

@@ -20,6 +20,7 @@ class CategoryList
     find_categories
 
     prune_empty
+    prune_muted
     find_user_data
     sort_unpinned
     trim_results
@@ -136,6 +137,10 @@ class CategoryList
     @categories.delete_if { |c| c.uncategorized? && c.displayable_topics.blank? }
   end
 
+  def prune_muted
+    @categories.delete_if { |c| c.notification_level == CategoryUser.notification_levels[:muted] }
+  end
+
   # Attach some data for serialization to each topic
   def find_user_data
     if @guardian.current_user && @all_topics.present?

spec/models/category_list_spec.rb

@@ -47,6 +47,16 @@ describe CategoryList do
       expect(CategoryList.new(Guardian.new(nil), include_topics: true).categories.find { |x| x.name == private_cat.name }).to eq(nil)
     end
 
+    it "properly hide muted categories" do
+      cat_muted = Fabricate(:category)
+      CategoryUser.create!(user_id: user.id,
+                           category_id: cat_muted.id,
+                           notification_level: CategoryUser.notification_levels[:muted])
+
+      # uncategorized + cat_muted for admin
+      expect(CategoryList.new(Guardian.new admin).categories.count).to eq(2)
+      expect(CategoryList.new(Guardian.new user).categories.count).to eq(1)
+    end
   end
 
   context "with a category" do