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From: dewar@cs.nyu.edu (Robert Dewar)
Subject: Re: Ada Core Technologies and Ada95 Standards
Date: 1996/04/01
Message-ID: <dewar.828397516@schonberg>#1/1
X-Deja-AN: 145335146
references: <00001a73+00002c20@msn.com> <dewar.827809782@schonberg>
 <828038680.5631@assen.demon.co.uk> <dewar.828062076@schonberg>
 <828127251.85@assen.demon.co.uk> <4jm0jv$9l2@fozzie.sun3.iaf.nl>
organization: Courant Institute of Mathematical Sciences
newsgroups: comp.lang.ada
Date: 1996-04-01T00:00:00+00:00
List-Id: <comp.lang.ada>

iJohn McCabe said

"`` I was obviously thinking of validation of Ada compilers in the same
   way that _my_ software is validated - i.e a full set of test cases
   proving that _all_ requirements have been met. ''"

I and others pointed out that this is obviously false for complex
software of any kind. If John really thinke he can provide this
proof via test cases, he is deluding himself (and his clients).

What is more interesting is that even a VERY simple program cannot
be provied by simple input-output tests. Consider the following
program to add the numbers from 1 to 10.

with Text_IO; use Text_IO;

procedure s is
   sum : integer;
begin
   for j in 1 .. 10 loop
      sum := sum + j;
   end loop;

   Put_Line (Integer'Image (j));
end;


this works fine on my machine. exhaustive testing (one case!!) proves
that it works, but of course it has a fatal problem, and may not work
tomorrow