raise exception on unknown option

spec/yawpa_spec.rb

@@ -3,11 +3,17 @@ require 'spec_helper'
 describe Yawpa do
   describe 'parse' do
     it "returns everything as arguments when no options present" do
-      config = { }
+      options = { }
       params = ['one', 'two', 'three', 'four']
-      opts, args = Yawpa.parse(config, params)
-      opts.should eq([])
+      opts, args = Yawpa.parse(params, options)
+      opts.should eq({})
       args.should eq(params)
     end
+
+    it "raises an exception when an invalid option is passed" do
+      options = { }
+      params = ['one', '--option', 'two']
+      expect { Yawpa.parse(params, options) }.to raise_error
+    end
   end
 end