class Shoulda::ActionController::Matchers::AssignToMatcher

def assigned_value?
  if assigned_value.nil?
    @failure_message =
      "Expected action to assign a value for @#{@variable}"
    false
  else
    @negative_failure_message = 
      "Didn't expect action to assign a value for @#{@variable}, " <<
      "but it was assigned to #{assigned_value.inspect}"
    true
  end
end