restrict comment hats to user's own hats

app/models/comment.rb

@@ -57,6 +57,9 @@ class Comment < ApplicationRecord
 
     self.comment.to_s.strip.match(/\Ame too.?\z/i) &&
       errors.add(:base, "Please just upvote the parent post instead.")
+
+    self.hat.present? && self.user.wearable_hats.exclude?(self.hat) &&
+      errors.add(:hat, "not wearable by user")
   end
 
   def self.arrange_for_user(user)

spec/models/comment_spec.rb

@@ -6,4 +6,20 @@
 
     expect(c.short_id).to match(/^\A[a-zA-Z0-9]{1,10}\z/)
   end
+
+  describe "hat" do
+    it "can't be worn if user doesn't have that hat" do
+      comment = Comment.make(hat: Hat.make!)
+      comment.valid?
+      expect(comment.errors[:hat]).to eq(['not wearable by user'])
+    end
+
+    it "can be one of the user's hats" do
+      user = User.make!
+      hat = Hat.make!(user_id: user.id)
+      comment = Comment.make!(user_id: user.id, hat: hat)
+      comment.valid?
+      expect(comment.errors[:hat]).to be_empty
+    end
+  end
 end

spec/support/blueprints.rb

@@ -43,6 +43,7 @@
   user_id { User.make!.id }
   story_id { Story.make!.id }
   comment { "comment text #{sn}" }
+  hat { nil }
 end
 
 Message.blueprint do