Merge pull request #157 from loftwah/dl/username-fix

Dl/username fix

Author: loftwah

app/models/user.rb

@@ -13,6 +13,10 @@ class User < ApplicationRecord
   has_many :link_clicks, dependent: :destroy
   has_many :achievement_views, dependent: :destroy
 
+  VALID_USERNAME_REGEX = /\A[a-zA-Z0-9_]+\z/
+
+  validates :username, presence: true, uniqueness: true, format: { with: VALID_USERNAME_REGEX, message: 'can only contain letters, numbers, and underscores' }
+
   validates :username, uniqueness: true, allow_blank: true
   validates :full_name, presence: true
   validate :ensure_username_presence

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