I used to use the WebStorm plugin for Go support, and never had any issues debugging tests. In GoLand, I've tried both directory test runs (runs fine, but debugging presents an error "Cannot run compiling on directory-kind run configurations") and file runs (errors out in both Run and Debug, saying that my types defined in the same package are undefined).
The test and code are in the same package, so there shouldn't be any issues with the types being undefined. The Go code is not in GOPATH, because it's a legacy all-in-one application. It'll be a fair amount of work to convert it for use in GOPATH, which I'd really like to avoid at the moment (time crunch being what it is at work).
I'm also not sure why directory-kind configurations aren't supported for debugging. Regardless, how can I actually debug my tests in GoLand? Since the WebStorm plugin is gone, I'm having to resort to logging statements and other nonsense that simply isn't convenient or efficient.