jtimberman

class Chef
  class Recipe
    def skip_unsupported_platform
      unless supported_platform?
        Chef::Log.info("Unsupported platform #{node[:platform]} in #{cookbook_name}::#{recipe_name}, skipping recipe")
        Chef::Log.debug("You said to skip unsupported platforms in #{cookbook_name}::#{recipe_name}")
        Chef::Log.debug("and #{node['platform']} is unsupported by cookbook #{cookbook_name}. Update the cookbook's metadata")
        Chef::Log.debug("if this is a supported platform, or remove #{cookbook_name}::#{recipe_name} from the node.")
      end
    end

acrmp

Example of mocking out a library in Chef so you can test the provider in isolation.

If you want to test the library itself you can do more normal Ruby things.