GNU bug report logs - #25351
26.0.50; Testcover doesn't work on code that creates simple lists and modifies them

Previous Next

Full log

View this message in rfc822 format

From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Gemini Lasswell <gazally <at> runbox.com>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#25351: closed (26.0.50; Testcover doesn't work on code that
 creates simple lists and modifies them)
Date: Sun, 08 Oct 2017 23:54:02 +0000

[Message part 1 (text/plain, inline)]

Your message dated Sun, 08 Oct 2017 16:53:40 -0700
with message-id <87po9xyz5n.fsf <at> runbox.com>
and subject line Re: bug#25351: Patch for bug#25351: 26.0.50; Testcover doesn't work on code that creates simple lists and modifies them
has caused the debbugs.gnu.org bug report #25351,
regarding 26.0.50; Testcover doesn't work on code that creates simple lists and modifies them
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs <at> gnu.org.)


-- 
25351: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=25351
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

[Message part 2 (message/rfc822, inline)]

From: Gemini Lasswell <gazally <at> runbox.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 26.0.50;
 Testcover doesn't work on code that creates simple lists and modifies
 them
Date: Tue, 03 Jan 2017 19:06:17 -0800

Testcover marks forms which have only returned a single value while under
code coverage with a tan splotch to indicate insufficient test coverage,
It also identifies forms which will only ever return a single value and
suppresses the splotch on those. During the coverage run, it saves a
reference to the return value of those single value forms, and the next
time the form is evaluated, it uses `equal' to determine if the value
has changed, and if it has, Testcover reports an error.

The problem with this is that it is a common idiom to create a data
structure using an expression that always returns the same thing, and
then modify it later. Since Testcover keeps a reference not a copy, it
ends up with a reference to a modified object, which fails the
comparison with the next return value of the same expression.

For example:

(defun my-blank-record ()
  (list (list 'name) (list 'age)))

(defun my-make-record (name age)
  (let ((rec (my-blank-record)))
    (setf (cdr (assq 'name rec)) name)
    (setf (cdr (assq 'age rec)) age)
    rec))

(my-make-record "Jack" 10)
(my-make-record "Jill" 12)

To reproduce this problem, save the above code in a file called bug.el,
and then:

M-x testcover-start RET bug.el RET

The result will be testcover-1value's "Value of form marked with
‘1value’ does vary" error.

[Message part 3 (message/rfc822, inline)]

From: Gemini Lasswell <gazally <at> runbox.com>
To: 25351-done <at> debbugs.gnu.org
Subject: Re: bug#25351: Patch for bug#25351: 26.0.50;
 Testcover doesn't work on code that creates simple lists and modifies
 them
Date: Sun, 08 Oct 2017 16:53:40 -0700

I've pushed this patch to master.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.