Re: Regression testing for pointers

From	Don Y <this@isnotme.com>
Newsgroups	comp.lang.c
Subject	Re: Regression testing for pointers
Date	2012-03-12 10:01 -0700
Organization	Aioe.org NNTP Server
Message-ID	<jjla4o$u2h$1@speranza.aioe.org> (permalink)
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Hi Nick,

On 3/12/2012 3:29 AM, nick_keighley_nospam@hotmail.com wrote:
> On Sunday, March 11, 2012 7:33:27 PM UTC, Don Y wrote:
>> On 3/11/2012 6:09 AM, nick_keighley_nospam@hotmail.com wrote:

>> [...] Yet that seems to be the most common approach to testing
>> nowadays (how many folks have formal specifications, test suites,
>> validation procedures, etc.).
>
> there's a system test spec and we have to comply to an international standard. This is verified by an external 3rd party.

Most folks operate with "none of the above".  How can you know
if you've written what you were *supposed* to write if you
don't have anything DEFINING it and PROVING your compliance??

>> You have to consciously *attack*/challenge a piece of code to
>> identify deficiencies.  Where are the boundary conditions?
>> What did the developer *not* expect?  etc.
>>
>> I tend to be pretty good at coming up with "unexpected"
>> operating conditions.  When the developer invariably
>> *whines* saying "but you're not supposed to *do* that!"
>> I grin and reply, "Then don't LET me!"
>
> I worked in a syetem test department for a while. I collected a
> list of best excuses "that hardly ever happens", "the customer
> would never do that" and my all time favourite "but the code
> says that's what happens!"

When you're moving a few tons of material and "fail to stop"
when expected, people's eyebrows raise!  :>  Or, if you
extract money from a machine and there is no record of
that event.

OTOH, The fact that your dialog box didn't get redrawn on an
expose event tends to get dismissed as unimportant.  ("Um,
if *that* isn't happening as planned/desired/DESIGNED, what
ELSE isn't??")

>>> This is one of the reasons the formal methods approach has been sluggish.
>>> In theory you prove a program is correct without ever executing it. But
>>> people rarely do this on any large scale.
>>
>> Actually, this is common on very large scale projects (which,
>> otherwise, would never be able to run a single invocation to
>> completion, otherwise).
>
> ? why not? Because they don't terminate?

Because they never run long enough without CRASHING!  :>

> I was talking about actual proofs of correctness. VDM, Z, Sparc.
> Are these widely used?

I've never found a case where you could apply such a technique
"across the board".  Rather, you want people who can imagine
the "impossible" and codify those conditions -- in their code
and in their test suites.

E.g., if I am driving a motorized mechanism "to the left",
I don't *just* watch the "left limit switch" and use that
to stop further motion.  What if the motor is wired
*backwards* and I am really moving the mechanism to the
*right*?  What if the limit switches are mixed up and
left is wired to right, etc.

If I am moving left, the RIGHT limit switch should NEVER
be actuated (ignore boundary case where the mechanism is
currently *at* that limit).  So, it should be perfectly
reasonable for me to watch the LEFT limit switch to
stop normal/EXPECTED motion... AND if I see activity on
the RIGHT limit switch, I can panic(), stop the mechanism,
etc.

In reality, this sort of "miswiring" *does* happen.
Especially on prototypes.  In that case, the cost of
ruining a mechanism can be EXTREMELY painful (we don't
have another one!).

But, it takes a perverse sort of mind to think about these
sorts of things.  And, teaching others to think the same
way is difficult.  I resort to having folks sit down and
list the ASSUMPTIONS they are making in any aspect of
design.  Then, ask yourself which of those are *truly*
safe!

E.g., if I have a "string" located at 0xFF...F8 that has
8 non-NUL characters in it, what should strlen() return?

>> Where it *doesn't* happen is smaller projects, "lone wolf"
>> developers, "immature" organizations, etc.  "Pay me now or
>> pay me later" is a great mantra when it comes to software
>> quality and testing, in general.
>>
>>> The writers of the Space Shuttle software might have achieved [] what
>>> you're trying to do. At enourmous cost.
>>
>> There are many industries where formal testing and validation
>> are the norm and "required" practices.
>
> yes. I know. The Space Shuttle software was a step above this. CMM level 5 and all that.
>
> Formal testing is not the same as formal methods

But formal testing WITHOUT formal methods is like buying food
that "Bob" said was prepared healthily.

(Great!  Who's Bob??)

If Bob is a highly respected individual KNOWN (renowned!) for
his dedication to healthy food, that might be a great
endorsement.  OTOH, if Bob is some anonymous guy...

Formal methods tries to take some of the variability out of
individual "preferences"/diligence.

Thread

Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-09 16:43 -0700
  Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-10 12:56 +1300
    Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-09 19:40 -0700
      Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-10 17:53 +1300
        Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-10 18:12 +1300
        Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-10 02:05 -0700
          Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-10 23:17 +1300
            Re: Regression testing for pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-10 12:00 +0000
              Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-11 11:00 +1300
                Re: Regression testing for pointers Ike Naar <ike@iceland.freeshell.org> - 2012-03-10 22:23 +0000
                Re: Regression testing for pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-10 22:40 +0000
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-11 12:12 +1300
                Re: Regression testing for pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-11 00:42 +0000
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-11 14:26 +1300
                Re: Regression testing for pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-11 03:09 +0000
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-11 18:16 +1300
            Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-10 12:01 -0700
              Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-11 10:35 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-12 09:19 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-13 07:23 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-12 16:23 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-13 17:25 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-13 00:19 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-13 20:34 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-13 01:00 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-13 21:22 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-13 10:19 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-14 07:25 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-14 02:00 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-14 22:18 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-14 11:32 -0700
                Re: Regression testing for pointers nick_keighley_nospam@hotmail.com - 2012-03-15 05:58 -0700
                Re: Regression testing for pointers nick_keighley_nospam@hotmail.com - 2012-03-15 05:55 -0700
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-15 11:32 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-16 18:14 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-20 01:43 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-20 21:59 +1300
                Re: Regression testing for pointers nick_keighley_nospam@hotmail.com - 2012-03-16 03:05 -0700
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-20 02:33 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-24 11:49 +1300
          Re: Regression testing for pointers nick_keighley_nospam@hotmail.com - 2012-03-11 05:01 -0700
            Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-11 09:44 -0700
              Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-12 09:56 +1300
    Re: Regression testing for pointers nick_keighley_nospam@hotmail.com - 2012-03-10 02:28 -0800
      Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-10 11:09 -0700
      Re: Regression testing for pointers Kaz Kylheku <kaz@kylheku.com> - 2012-03-10 18:29 +0000
        Re: Regression testing for pointers nick_keighley_nospam@hotmail.com - 2012-03-11 05:22 -0700
          Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-11 09:50 -0700
            Re: Regression testing for pointers "io_x" <a@b.c.invalid> - 2012-03-13 13:09 +0100
  Re: Regression testing for pointers Kaz Kylheku <kaz@kylheku.com> - 2012-03-10 03:14 +0000
    Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-10 12:42 -0700
  Re: Regression testing for pointers Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-03-10 08:42 +0000
    Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-10 02:19 -0700
      Re: Regression testing for pointers "BartC" <bc@freeuk.com> - 2012-03-10 15:54 +0000
        Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-10 11:49 -0700
          Re: Regression testing for pointers nick_keighley_nospam@hotmail.com - 2012-03-11 06:09 -0700
            Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-11 12:33 -0700
              Re: Regression testing for pointers nick_keighley_nospam@hotmail.com - 2012-03-12 03:29 -0700
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-12 10:01 -0700
                Re: Regression testing for pointers "BartC" <bc@freeuk.com> - 2012-03-13 18:56 +0000
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-13 16:31 -0700
      Re: Regression testing for pointers Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-03-12 00:30 +0000
        Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-12 16:41 -0700
      Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-12 13:39 +1300
        Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-12 09:36 -0700
          Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-13 07:25 +1300
            Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-12 16:28 -0700
              Re: Regression testing for pointers Kaz Kylheku <kaz@kylheku.com> - 2012-03-13 04:20 +0000
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-13 17:34 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-13 00:29 -0700
              Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-13 17:31 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-13 01:05 -0700
                Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-13 21:30 +1300
                Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-13 10:43 -0700
  Re: Regression testing for pointers Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-03-10 15:41 -0800
    Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-11 11:23 -0700
      Re: Regression testing for pointers Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-03-13 13:43 -0700
        Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-14 01:45 -0700
          Re: Regression testing for pointers Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-03-14 15:15 -0700
            Re: Regression testing for pointers Kaz Kylheku <kaz@kylheku.com> - 2012-03-14 22:57 +0000
              Re: Regression testing for pointers Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-03-15 13:10 -0700
                Re: Regression testing for pointers jgk@panix.com (Joe keane) - 2012-03-16 22:20 +0000
                Re: Regression testing for pointers "io_x" <a@b.c.invalid> - 2012-03-18 07:15 +0100
            Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-14 23:13 -0700
  Re: Regression testing for pointers gordonb.b29ri@burditt.org (Gordon Burditt) - 2012-03-12 19:37 -0500
    Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-12 19:23 -0700
  Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-14 13:12 +1300
    Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-14 01:54 -0700
      Re: Regression testing for pointers Ian Collins <ian-news@hotmail.com> - 2012-03-14 22:05 +1300
        Re: Regression testing for pointers Don Y <this@isnotme.com> - 2012-03-14 11:54 -0700

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