title: creating an object variable in rspec test but got nil
body: <p>here is my rspec code:</p>
  
  <pre><code>describe User do
    before{(@user=User.new(username:"abcdefg",email:"123456@123.com",password:"123456")}
    subject(@user)
    @user.save
  end
  </code></pre>
  
  <p>and I got such an error : <code>undefined method 'save' for nil:NilClass(NoMethodError)</code></p>
  
  <p>I try to write the same code in the rails console,it just worked. But when it comes to Rspec,it failed and I'm not able to find any reason... </p>
  
  <p>Could any one help me with it?</p>