phobos unit tests

[Jonathan M Davis via Digitalmars-d]

On Saturday, September 03, 2016 15:06:33 Andrei Alexandrescu via Digitalmars-d 
wrote:
> On 9/3/16 5:36 AM, Manu via Digitalmars-d wrote:
> > This document: https://wiki.dlang.org/Contributing_to_Phobos
> >
> > States: "Avoid unittest in templates (it will generate a new unittest
> > for each instance) - put your tests outside"
>
> Actually that's a good thing, sometimes you do want to run a unittest
> for each instantiation.

Sometimes, sure. But usually not.

> > Sounds reasonable, but then I realised that most of my unit tests are
> > documenting unittests... this recommendation is in conflict with the
> > documentation standards... who wins?
>
> Just version it only for the documentation.

Then the tests won't be run unless your documentation build is also your
unittest build, and they frequently can't be the same - e.g. when something
differs between operating systems, and you have a separate D_Ddoc or StdDdoc
block so that you can have proper documentation without requiring that the
documentation be built on all systems and potentially being able to document
what exists on each system. For instance, the supported clock types vary
quite a bit across operating systems, so the core.time.ClockType enum has
different values on different systems and version(CoreDdoc) is used so that
the documentation can list them all and list the consistently across
systems.

You could add some sort of version identifier that's specific to your build
that you use for your unittest builds (similar to how Phobos has StdDdoc
separate from D_Ddoc), but even if you do that, you still have the problem
of the non-generic unit tests within a template being compiled into every
instantiation of the template that's part of your unittest build, and all of
those tests will get run, increasing both the build times and the time it
takes to run the unit tests.

- Jonathan M Davis