fix comparison test and helpers

moving to passing the instruction number, not the instruction
so in the error message we can say where the error is
(otherwise minitest is good enough to supress the trace of asserts calling asserts)

lib/slot_machine/macro/comparison.rb

@@ -13,8 +13,8 @@ module SlotMachine
     def to_risc(compiler)
       builder = compiler.builder(compiler.source)
       operator = @operator # make accessible in block
-      false_label = Risc.label("false" , "false")
-      merge_label = Risc.label("merge" , "merge")
+      false_label = Risc.label("false" , "false_label_#{object_id}")
+      merge_label = Risc.label("merge" , "merge_label_#{object_id}")
       result = Risc::RegisterValue.new(:result , :Object)
       builder.build do
         left = message[:receiver].to_reg.reduce_int
@@ -26,7 +26,7 @@ module SlotMachine
           left.op :- , right
         end
         if_minus false_label
-        if_zero( false_label ) if operator.to_s.length == 1
+        if_not_zero( false_label ) if operator.to_s.length == 1
         add_code Risc::LoadConstant.new(to_s , Parfait.object_space.true_object, result)
         branch merge_label
         add_code false_label