make interpreter tests less brittle

by factoring __init code away
just counting main

test/support/risc.rb

@@ -2,18 +2,37 @@ module Risc
   # relies on @interpreter instance to be set up during setup
   module InterpreterHelpers
 
-    def check_chain should
+    # check the given array of instructions is what the interpreter actually does
+    # possible second argument ignores the given amount, usually up until main
+    def check_chain( should , start_at = 0 )
+      ticks( start_at ) if start_at > 0
       should.each_with_index do |name , index|
         got = ticks(1)
-        assert_equal got.class ,name , "Wrong class for #{index+1}, expect #{name} , got #{got}"
+        assert_equal got.class ,name , "Wrong class for #{index + 1 - start_at}, expect #{name} , got #{got}"
       end
     end
+    # check the main only, ignoring the __init instructions
+    def check_main_chain( should )
+      check_chain( should , main_at)
+    end
+
+    # how many instruction up until the main starts, ie
+    # ticks(main_at) will be the label for main
+    def main_at
+      26
+    end
 
     def get_return
       assert_equal Parfait::Message , @interpreter.get_register(:r0).class
       @interpreter.get_register(:r0).return_value
     end
 
+    # do as many as given ticks in the main, ie main_at more
+    def main_ticks(num)
+      ticks( main_at + num)
+    end
+
+    # do a certain number of steps in the interpreter and return the last executed instruction
     def ticks( num )
       last = nil
       num.times do
@@ -23,7 +42,8 @@ module Risc
       return last
     end
 
-    def show_ticks
+    # collect the classes of all executed istructions
+    def all_classes
       classes = []
       tick = 1
       begin
@@ -38,6 +58,22 @@ module Risc
         puts e
         puts e.backtrace
       end
+      classes
+    end
+
+    # for chaning the tests quickly output all instructions that are executed
+    def show_ticks
+      classes = all_classes
+      output_classes(classes)
+    end
+    # show all instructions of the main only
+    def show_main_ticks
+      classes = all_classes
+      classes = classes.slice(main_at , 1000)
+      output_classes(classes)
+    end
+
+    def output_classes(classes)
       str = classes.to_s.gsub("Risc::","")
       all = str.split(",").each_slice(5).collect {|line| "            " + line.join(",")}
       puts all.join(",\n")