title: Why do I get the same object when I use create_list in the FactoryGirl and the sample method?
body: <p>I use factory girl to define a object like this:</p>
  
  <pre><code>factory :event do
    #...
    category ['Life', 'Course', 'Speek'].sample
    #...
  end
  </code></pre>
  
  <p>Then in the <code>spec/models/event_spec.rb</code>, I have this:</p>
  
  <pre><code>before(:each) do
    @events = FactoryGirl.create_list(:event, 10, node: school) 
  end
    #...
  binding.pry   
  </code></pre>
  
  <p>But when I used pry to check the <code>@events</code>, I found that all the <code>event</code> in the <code>@events</code> has the same <code>category</code>.</p>
  
  <p>I want to know why and how to solve it ? Thanks in advance.</p>