add spec for Boxed#to_a change

test/test/spec/boxed_spec.rb

@@ -2,4 +2,9 @@ describe "Boxed" do
   it ".type should work with structure which has field of structure pointer" do
     MyStructHasStructPointer.type.should == "{MyStructHasStructPointer=^{MyStruct4C}}"
   end
+
+  it ".to_a should recursively call #to_a on fields of the Boxed type" do
+    rect = CGRect.new(CGPoint.new(1, 2), CGSize.new(3, 4))
+    rect.to_a.should == [[1.0, 2.0], [3.0, 4.0]]
+  end
 end