How can one reliably run unittests

[jfondren]

On Thursday, 2 September 2021 at 19:16:38 UTC, jfondren wrote:
> The fact is that dmd is a compiler and not a build system.
...
> I think there's an argument to be made that maybe a 'dmd test' 
> should be added to run the tests of a single module.

Nah, this discussion is meandering due to some frustration and 
some specific complaints taking the place of the original 
complaint. If anyone's following this thread, this is a good time 
to go back to the original post: 
https://forum.dlang.org/post/rgalgunhtubgeoyrfwxd@forum.dlang.org

Where the use case is roughly

1. the developer is knee-deep in a big D project with a bunch of 
dependencies and modules
2. the developer is doing work on a single module
3. the developer wants to run that module's tests to confirm that 
#2 didn't break anything
4. the developer wants to do this without incurring a "testing!" 
variant of https://xkcd.com/303/ and without needing a bunch of 
boilerplate like Unittest_ThisModule version blocks in each 
module.