I'm probably not using it to the fullest. I mostly use it for boilerplate that I know it's good at, like `// Write a function to run the cpu profiler for 30 seconds and write the result to the filename in variable "foo"`. But I guess if it knows your codebase, then you can say `// Write a test to ensure that Foo accepts a nil FooRequest.` or something. I should figure out how to set that up.
All in all it saves me a little bit of typing a couple of times a week.
You should try it on vscode for a moment or try to find a plugin for emacs.
I'm often writing legal rules in code and from the name of my function, it predicts the way the law is written. It's pretty incredible how well it works. Clearly it's just stealing someone else's work from github, but the autocomplete is very awesome.
All in all it saves me a little bit of typing a couple of times a week.