Add ContactsController spec - 05_controller_basics
user
```ruby
require 'spec_helper'

describe ContactsController do
  describe 'GET #index' do
    context 'with params[:letter]' do
      it "populates an array of contacts starting with the letter"
      it "render the :index template"
    end

    context 'without params[:letter' do
      it "populates an array of all contacts"
      it "renders the :index template"
    end
  end

  describe 'GET #show' do
    it "assigns the requested contact to @contact"
    it "renders the :show template"
  end

  describe 'GET #new' do
    it "assigns a new Contact to @contact"
    it "renders the :new template"
  end

  describe 'GET #edit' do
    it "assigns the requested contact to @contact"
    it "renders the :edit template"
  end

  describe 'POST #create' do
    context 'with valid attributes' do
      it "saves the new contact in the database"
      it "redirects to contacts#show"
    end

    context 'with invalid attributes' do
      it "does not save the new contact in the database"
      it "re-renders the :new template"
    end
  end

  describe 'PATCH #update' do
    context 'with valid attributes' do
      it "updates the contact in the database"
      it "redirects to the contact"
    end

    context 'without valid attributes' do
      it "does not update the contact in the database"
      it "re-renders the #edit template"
    end
  end

  describe 'DELETE #destroy' do
    it "deletes the contact from the database"
    it "redirects to users#index"
  end
end
```
assistant