How to debug/test custom frontends

[mxab]

Hi,

I'm building a custom frontend for docker so I can use it like docker build -f ... .

I looked a bit at other projects like Mockerfile
Gockerfile , but it is currently not clear to me how to debug an actual build.

Also I was wondering if there is any way to write proper test cases for the build part, especially for the part that happens inside the grpcclient.RunFromEnvironment( part