Not quite sure what you are looking for but Go was one of the first languages about 7-8 years ago that had unit testing, benchmarking and code coverage built into the standard library and tooling.
The unique implementation of automatically satisfied Interfaces and first class functions (ie. easy to inject dependency) in particular makes testing very easy and designing code using these abstractions for testability also improves modularity.
For database, generally you just use the standard library to access and well tested database drivers provide the actual access mechanics. So if you want you can actually decouple tests checking the business logic side of database (eg. instantiate and hit an in-memory dB locally during testing - or even use a completely different driver if you're not using a weird "flavor" of SQL) from actual connectivity testing (where you wrap things into a transaction in a real mirror dB)