adds ivar collection with tests

test/vool/compilers/test_variables.rb

@@ -0,0 +1,32 @@
+require_relative "helper"
+
+module Vool
+  module Compilers
+    class TestIvarCollect < MiniTest::Test
+
+      def compile(input)
+        lst = VoolCompiler.compile( input )
+        vars = []
+        lst.collect([]).each do |node|
+          node.add_ivar(vars)
+        end
+        vars
+      end
+
+      def test_instance_collect
+        vars = compile( "@var" )
+        assert_equal :var , vars.first
+      end
+
+      def test_return_collect
+        vars = compile( "return @var" )
+        assert_equal :var , vars.first
+      end
+
+      def ttest_assign_collect
+        vars = compile( "@var = 5" )
+        assert_equal :var , vars.first
+      end
+    end
+  end
+end