added some more arity tests

git-svn-id: https://dev.finn.de/svn/cockpit/branches/reporting_merge@1840 7926756e-e54e-46e6-9721-ed318f58905e

spec/models/cost_query/operator_spec.rb

@@ -193,7 +193,7 @@ describe CostQuery do
     end
 
     describe 'arity' do
-      arities = {'t' => 0}
+      arities = {'t' => 0, 'w' => 0, '<>d' => 2, '>d' => 1}
       arities.each do |o,a|
         it("#{o} should take #{a} values") { o.to_operator.arity.should == a }
       end