fix list to expand

prevously fixed max length list
now expanding on demand, using next
quite like binary_code, a pattern is emerging

test/parfait/test_list2.rb

@@ -0,0 +1,36 @@
+require_relative "helper"
+
+module Parfait
+  class TestListTooMany < ParfaitTest
+    def setup
+      super
+      @list = ::Parfait::List.new
+      @list.data_length.times { |i| @list.push i.to_s }
+    end
+    def add_two
+      @list.push(@list.data_length.to_s)
+      @list.push((@list.data_length + 1).to_s)
+    end
+    def test_next
+      assert_nil @list.next
+    end
+    def test_setup_len
+      assert_equal List.data_length , @list.get_length
+    end
+    def test_setup_last
+      assert_equal (List.data_length - 1).to_s , @list.last
+    end
+    def test_length_two
+      add_two
+      assert_equal List.data_length + 2 , @list.get_length
+    end
+    def test_get_last
+      add_two
+      assert_equal (List.data_length + 1).to_s , @list.last
+    end
+    def test_get_but_last
+      add_two
+      assert_equal List.data_length.to_s , @list[List.data_length]
+    end
+  end
+end