Re: A simple unit test framework

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

8 May 2007 03:07:46 -0700

Message-ID:

<1178618866.653457.216330@e51g2000hsg.googlegroups.com>

On May 8, 3:21 am, Gianni Mariani <gi3nos...@mariani.ws> wrote:

Branimir Maksimovic wrote:

...

These two are sure sign of possible undefined behavior.
I can bet that Task's start function, passes context
of object into other thread while construction still works
in first one. Since call to member function is made,
no wonder that you can't do this in constructor/destructor
of base class.

Yeah - I know - technically speaking you're right - practically speaking
it's not an issue. It's platform specific for any platform that works.
So far that UB is working as expected on every platform I have tested
so I have not bothered to fix it.

Supposing, of course, that HardTask is the most derived class.
(which I'm pretty sure is the case).

This is also same example I gave for incorrect code for which test
case showing failure cannot be reliably written ;)

For which definition of reliability ? That code is reliable at least on
the platforms it compiles on - at the moment. Also, I am not alone with
this one and so it is becoming a de-fact standard anyway.

There is an impedence mismatch here with regards to what can be
specified clearly in the standard, and what actually works.
Practically speaking, provided you have ensured proper
synchronization in Start, etc., an implementation where your
specific code won't work is impossible. Try writing a
specification, however, that defines its behavior, but doesn't
allow cases where you don't actually initialize something until
after the call to Start.

But for playing with ub in this case, I would write test case code
deriving from HardTask, implementing Work and try to play with some
member variables ;)

The *right* way to use task is to call Start in the most derived
constructor ... and Wait() in the most derived destructor. Anything
else is UB - i.e. not supported.

And of course, Start() must be *after* all essential
initializations in the constructor, and Wait() before you start
tearing things down in the destructor.

--
James Kanze (Gabi Software) email: james.kanze@gmail.com
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