diff --git a/spec/models/thredded/category_spec.rb b/spec/models/thredded/category_spec.rb
index <HASH>..<HASH> 100644
--- a/spec/models/thredded/category_spec.rb
+++ b/spec/models/thredded/category_spec.rb
@@ -3,20 +3,5 @@ require 'spec_helper'
 
 module Thredded
   describe Category do
-    it 'should allow no categories' do
-      topic = create(:topic)
-      topic.category_ids = nil
-      topic.save
-
-      expect(topic).to be_valid
-    end
-
-    it 'should allow a category' do
-      topic = create(:topic)
-      topic.categories << create(:category, messageboard: topic.messageboard)
-      topic.save
-
-      expect(topic.categories).not_to be_nil
-    end
   end
 end
diff --git a/spec/models/thredded/topic_spec.rb b/spec/models/thredded/topic_spec.rb
index <HASH>..<HASH> 100644
--- a/spec/models/thredded/topic_spec.rb
+++ b/spec/models/thredded/topic_spec.rb
@@ -124,5 +124,16 @@ module Thredded
 
       expect(@post.postable.reload.updated_at.to_s).to eq old_time.to_s
     end
+
+    it 'can have categories' do
+      topic    = build(:topic)
+      category = build(:category)
+
+      topic.categories << category
+      topic.save
+
+      expect(topic.categories.size).to eq 1
+      expect(topic.categories.first).to eq category
+    end
   end
 end
Update specs (#<I>)

* remove specification about a behaviour belonging to another model (topic)

* specify only expected behaviour to avoid over specification (previously it was specified that "don't should allow no categories" ).