Spec for posting to no group

app/models/user.rb

@@ -45,9 +45,11 @@ class User
     options[:person] = self.person
 
     group_ids = options[:to]
+
+    raise "You must post to someone." if group_ids.nil? || group_ids.empty?
+
     group_ids = [group_ids] unless group_ids.is_a? Array
 
-    return nil if group_ids.nil? || group_ids.empty?
     group_ids.map!{|gid| ensure_bson gid }
     options.delete(:to)
 

spec/models/user/posting_spec.rb

+require File.dirname(__FILE__) + '/../../spec_helper'
+
+describe User do
+   before do
+      @user = Factory.create(:user)
+      @group = @user.group(:name => 'heroes')
+   end
+  it 'should not be able to post without a group' do
+    proc {@user.post(:status_message, :message => "heyheyhey")}.should raise_error /You must post to someone/ 
+  end
+end