Add User.find_by_username!

app/controllers/users_controller.rb

@@ -50,7 +50,7 @@ class UsersController < ApplicationController
   private
 
   def set_user
-    @user = User.find_by!('lower(username) = ?', params[:username].downcase)
+    @user = User.find_by_username!(params[:username])
 
     unless current_user || @user.public_profile?
       return authenticate_user!

app/models/user.rb

@@ -274,6 +274,10 @@ class User < ActiveRecord::Base
             value: login.to_s.downcase).first
     end
 
+    def find_by_username!(username)
+      find_by!('lower(username) = ?', username.downcase)
+    end
+
     def by_username_or_id(name_or_id)
       where('users.username = ? OR users.id = ?', name_or_id.to_s, name_or_id.to_i).first
     end

spec/models/user_spec.rb

@@ -442,6 +442,18 @@ describe User do
     end
   end
 
+  describe '.find_by_username!' do
+    it 'raises RecordNotFound' do
+      expect { described_class.find_by_username!('JohnDoe') }.
+        to raise_error(ActiveRecord::RecordNotFound)
+    end
+
+    it 'is case-insensitive' do
+      user = create(:user, username: 'JohnDoe')
+      expect(described_class.find_by_username!('JOHNDOE')).to eq user
+    end
+  end
+
   describe 'all_ssh_keys' do
     it { is_expected.to have_many(:keys).dependent(:destroy) }