Fail when `file_write' misses some arguments

lib/producer/core/actions/file_writer.rb

@@ -3,6 +3,10 @@ module Producer
     module Actions
       class FileWriter < Action
         def setup
+          if arguments.compact.size != 2
+            fail ArgumentError, '`%s\' action requires 2 arguments' % name
+          end
+
           @path, @content         = arguments
           @options[:permissions]  = @options.delete :mode if options.key? :mode
           @options[:owner]        = @options.delete :user if options.key? :user

lib/producer/core/errors.rb

@@ -2,6 +2,7 @@ module Producer
   module Core
     Error                       = Class.new(StandardError)
     RuntimeError                = Class.new(RuntimeError)
+    ArgumentError               = Class.new(Error)
     ConditionNotMetError        = Class.new(Error)
     RemoteCommandExecutionError = Class.new(RuntimeError)
     RegistryKeyError            = Class.new(RuntimeError)