Make username parameter for Users#show case-insensitive

Closes #2012

app/controllers/users_controller.rb

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

spec/controllers/users_controller_spec.rb

 require 'spec_helper'
 
 describe UsersController do
-  let(:user)    { create(:user, username: 'user1', name: 'User 1', email: 'user1@gitlab.com') }
+  let(:user) { create(:user) }
 
-  before do
+  describe 'GET #show' do
+    it 'is case-insensitive' do
+      user = create(:user, username: 'CamelCaseUser')
       sign_in(user)
+
+      get :show, username: user.username.downcase
+
+      expect(response).to be_success
     end
 
-  describe 'GET #show' do
+    context 'with rendered views' do
       render_views
 
       it 'renders the show template' do
+        sign_in(user)
+
         get :show, username: user.username
-      expect(response.status).to eq(200)
+
+        expect(response).to be_success
         expect(response).to render_template('show')
       end
     end
+  end
 
   describe 'GET #calendar' do
     it 'renders calendar' do
+      sign_in(user)
+
       get :calendar, username: user.username
+
       expect(response).to render_template('calendar')
     end
   end
@@ -30,6 +43,8 @@ describe UsersController do
 
     before do
       allow_any_instance_of(User).to receive(:contributed_projects_ids).and_return([project.id])
+
+      sign_in(user)
       project.team << [user, :developer]
     end