Building custom library package with dub

[alex1974 via Digitalmars-d-learn]

On Saturday, 18 March 2017 at 13:41:12 UTC, Mike Parker wrote:
> On Saturday, 18 March 2017 at 12:49:33 UTC, alex1974 wrote:
>
>>
>> This simple layout works, but then all parts will be compiled 
>> every time. Is there a way to just compile the "sublibraries" 
>> which have changed?
>
> By "compiled every time", if you're talking about when using 
> the library as a dependency, that's not quite true. dub will 
> compile dependencies on the first run, then only in specific 
> scenarios, not every time. It's really not a big deal. Take a 
> look at dlib [1], for example. On big monolithic library and I 
> haven't seen anyone complaining.
>
> But if you really want to, take a look at subpackages[2] in the 
> dub docs.
>
> [1] https://github.com/gecko0307/dlib
> [2] https://code.dlang.org/package-format?lang=json#sub-packages

Actually the compiling is fast. But its confusing, that all 
unittests from all sublibraries are performed every time.
I thought with subpackages I can perform just the test from the 
part I'm working on.
But I can't get the right layout for the subpackages.