Refactor Readable.readable_parent to consider all ancestors

lib/unread/readable.rb

@@ -58,11 +58,7 @@ def read_scope(reader)
       end
 
       def readable_parent
-        current_klass = self
-        while(ReadMark.readable_classes.include?(current_klass.superclass)) do
-          current_klass = current_klass.superclass
-        end
-        current_klass
+        self.ancestors.find { |ancestor| ReadMark.readable_classes.include?(ancestor) }
       end
 
       def cleanup_read_marks!

spec/app/models/multi_level_sti_readable.rb

@@ -0,0 +1,2 @@
+class MultiLevelStiReadable < Email
+end

spec/spec_helper.rb

@@ -19,6 +19,7 @@
 require 'app/models/sti_reader'
 require 'app/models/document'
 require 'app/models/email'
+require 'app/models/multi_level_sti_readable'
 
 # Requires supporting ruby files with custom matchers and macros, etc,
 # in spec/support/ and its subdirectories.

spec/unread/garbage_collector_spec.rb

@@ -8,7 +8,7 @@
     wait
     @email1 = Email.create!
     wait
-    @email2 = Email.create!
+    @email2 = MultiLevelStiReadable.create!
   end
 
   describe :run! do

spec/unread/readable_spec.rb

@@ -8,7 +8,7 @@
     wait
     @email1 = Email.create!
     wait
-    @email2 = Email.create!
+    @email2 = MultiLevelStiReadable.create!
   end
 
   describe :unread_by do

spec/unread/reader_spec.rb

@@ -8,7 +8,7 @@
     wait
     @email1 = Email.create!
     wait
-    @email2 = Email.create!
+    @email2 = MultiLevelStiReadable.create!
   end
 
   describe :have_not_read do
@@ -178,4 +178,4 @@
       expect(readers[0].have_read?(@email2)).to be_falsey
     end
   end
-end
+end