Kernel depends on non-kernel code (BasicContentTypeImageService can't be used in unit tests)

I was looking at writing a test for ZipContentUtil and discovered that ZipContentUtil requires a functioning org.sakaiproject.content.impl.BasicContentTypeImageService.

Now all the type information seems to have been extracted out the kernel and into the config project BasicContentTypeImageService returns NPE when calling some methods.

Shouldn't the kernel be self contained and not be relying on external services for it's core functionality?