Code content folding in test screen doesn't exist.
not sure if it is a bug , an intended behavior, an oversight ...
It's not a major show stopper (at least for me), but would be nice to have.
(seems like all you have to do is to attach parser that already used in Program window screen to build code tree)

The Test Window does indeed not have the features that are primarily useful when working with large sources, such as code contents, code hierarchy and code folding.

Still, it would be really useful when stepping through large sources...