Re: Unit Testing Frameworks (was Re: Singletons)

Balog Pal <>
Sun, 30 Dec 2012 14:26:18 -0800 (PST)
On 12/30/2012 9:31 AM, Dave Abrahams wrote:

on Fri Dec 28 2012, Ian Collins <> wrote:

It seems self-evident to me, but I'll try to explain anyway.

* Most singletons are designed not to allow arbitrary lifetime
    management at all, so you can only have one during the life of
    the executable

* In any case, only one instance of a singleton can exist at a
    given time, by definition

* Therefore if you have two tests that need to talk to different
    loggers they either must be in separate executables (in the
    first case) or at least can't run in separate threads (in the
    second case).

What am I missing?

Unit tests normally (in the case of a singleton, nearly always)

FWIW, I wasn't talking about testing the singleton, but about
testing the components that /use/ the singleton.

use mocks for foreign objects required by the tests. I think that
was clear from the examples in this thread using a type called

Even if that's true, I don't see how that relates to my points above.

If you're not bother with testing the singleton itself, just use it,
the road is pretty clear. Consider the mother of all singletons in the
C++ system, the free store. Everyone is allowed to use any
memory-related functions and how much does it hurt testability,
including the proposed randomly parallelized one?

I'm yet to hear proposals to smuggle that in via DI too. ;-)

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