The first step is to really question if you need this level of complexity. Remove the things that provide no value. Break out data transformations into their ow

The first step is to really question if you need this level of complexity. Remove the things that provide no value. Break out data transformations into their own processes or microservices. Isolate them and really treat them like a black box. Unit test heavily here. Go is built for microservices. I've got a go application that I've inherited that's very light on the unit testing and heavy on the end to end integration testing. Golang doesn't make this sort of thing easy or enjoyable. I'll probably rip a lot of that out if we wind up changing major parts of it. Remember, testing is an insurance policy. It provides no direct value to the business. That's not to say it shouldn't be done, it most certainly should. But when testing becomes the majority of your coding effort then it's time to start re-evaluating your testing approach.