fix test

Author: loftwah

spec/models/user_spec.rb

@@ -1,10 +1,9 @@
-# spec/models/user_spec.rb
 require 'rails_helper'
 
 RSpec.describe User, type: :model do
   describe 'validations' do
     it { should validate_presence_of(:email) }
-    it { should validate_uniqueness_of(:username).allow_blank }
+    it { should validate_uniqueness_of(:username) }  # Removed .allow_blank
     it { should validate_presence_of(:full_name) }
   end
 
@@ -67,4 +66,4 @@
       expect(user.parsed_tags).to eq(['ruby', 'rails'])
     end
   end
-end
+end