Rspec ne voit pas mon modèle de Classe. uninitialized constant d'erreur

Je suis en train d'écrire des tests sur Rspec pour mes modèles en Ruby on Rails application.
Et je reçois cette erreur lors du démarrage de 'rspec spec'

command:
/spec/models/client_spec.rb:4:in `<top (required)>': uninitialized constant Client (NameError)

- Je utiliser Rails 4.0.0 et Ruby 2.0.0

Voici mon client_spec.rb:

require 'spec_helper'


describe Client do

  it 'is invalid without first_name', :focus => true do
     client = Client.new
     client.should_not be_valid
  end
end

Et Gemfile:

source 'https://rubygems.org'

# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.0.0.rc1'

# Use sqlite3 as the database for Active Record
gem 'sqlite3'

# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.0.rc1'

# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'

# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'

# gem 'therubyracer', platforms: :ruby

# Use jquery as the JavaScript library
gem 'jquery-rails'

# Turbolinks makes following links in your web application faster. Read more: 
gem 'turbolinks'

gem 'jbuilder', '~> 1.0.1'

group :development do
  gem 'rspec-rails'
end

group :doc do
  # bundle exec rake doc:rails generates the API under doc/api.
  gem 'sdoc', require: false
end

group :test do
  gem 'rspec-rails'
  gem 'factory_girl_rails'
  gem 'database_cleaner'
end

Et au dernier client.rb (ROR Modèle et de la Classe):

class Client < ActiveRecord::Base

  has_many :cars
  has_many :orders
  has_one :client_status
  has_one :discount_plan, through: :client_status

  validates :email, format: { with: /^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,4})\z/, :message => "Only emails allowed", :multiline => true }
  validates :email, presence: true, if: "phone.nil?"
  #validates :phone, presence: true, if: "email.nil?"
  validates :last_name, :first_name, presence: true
  validates :last_name, :first_name, length: {
      minimum: 2,
      maximum: 500,
      wrong_length: "Invalid length",
      too_long: "%{count} characters is the maximum allowed",
      too_short: "must have at least %{count} characters"
     }
end

Si il serais utile mon spec_helper.rb.rb fichier:

# This file was generated by the `rspec --init` command. Conventionally, all
# specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
# Require this file using `require "spec_helper"` to ensure that it is only
# loaded once.
#
# See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
RSpec.configure do |config|
  config.treat_symbols_as_metadata_keys_with_true_values = true
  config.run_all_when_everything_filtered = true
  config.filter_run :focus

  # Run specs in random order to surface order dependencies. If you find an
  # order dependency and want to debug it, you can fix the order by providing
  # the seed, which is printed after each run.
  #     --seed 1234
  config.order = 'random'

  #config.use_transactional_fixtures = false

  config.before(:suite) do
    DatabaseCleaner.strategy = :transaction
    DatabaseCleaner.clean_with(:truncation)
  end

   config.before(:each) do
     DatabaseCleaner.start
   end

   config.after(:each) do
     DatabaseCleaner.clean
   end

  end