f.select with enum in rails 3

I have model,

class Test < ActiveRecord::Base
  as_enum :test, [:test, :test_1, :test_1_2]
end

I need to create a f.select dropdown with enum. But I am facing an issue preparing dropdown with enum.

Here is my code:

<%= f.select :test, options_for_select(Test.tests.keys.to_a), {}, :class => "form-control" %>

But prepared a wrong select box.

http://grab.by/HSM2

Can anyone have any suggestion?