This go module demonstrates the power of export_test.go.
The athena package wraps the Athena SDK provided by the laborious AWS Go SDK.
If I were to do this again - I would avoid wrapping the AWS glue client in a struct for a single method (or perhaps even multiple methods), instead opting to use a function that receives a glue client interface parameter.
I can still mock, but wouldn't need to bother with export_test.go idiom at all.
But the example still serves the purpose of demonstrating how it is used.