[chef] NoMethodError - undefined method `[]' for nil:NilClass

[David Montgomery < >]

I have the below in a chef recipie

server_type = node[:test][:server_type]

In a role I have the below:

default_attributes "test" => { "server_type" => 'Compute' }

yet I get the below error

35: 
 36>> server_type = node[:test][:server_type]
[2013-07-18T01:16:55+00:00] DEBUG: Re-raising exception: NoMethodError - undefined method `[]' for nil:NilClass

How do I resolve?