And how does Devel::Cover detect that unexecuted function call that you described back there somewhere?

Coverage checks are intended to determine how much of your code is exercised by your test suite. The basic presumption is that your test suite should call everything. If something is missed it's an indication that your test suite either needs more tests, or you have functions you aren't using.

This differs from checking for unused functions by a chunk of code. A chunk of code, be it a script or a module, is not necessarily supposed to call every function possible on any given execution.

So, what you are saying is that the advice to "build a comprehensive test suite" and then use a manual, step-by-step "rename a sub at random and run the test suite to see what happens" advice will, after all the laborious and manually intensive effort involved, miss the very same example that your pointed out that my fast and mostly automated method would miss:

C:\test>type junk8.pl
#! perl -slw
use strict;

foo() if @ARGV;

C:\test>perl -MDevel::Cover junk8.pl
Devel::Cover 0.61: Collecting coverage data for branch, condition, pod
+, statement, subroutine and time.
Selecting packages matching:
Ignoring packages matching:
    /Devel/Cover[./]
Ignoring packages in:
    .
    c:/Perl/lib
    c:/Perl/site/lib

Devel::Cover: Can't find file "blib\lib\Storable.pm" (blib\lib\Storabl
+e.pm (autosplit into blib\lib\auto\Storable\retrieve.al)): ignored.
Devel::Cover: Writing coverage database to C:/test/cover_db/runs/11934
+13458.532.60512

---------------------------- ------ ------ ------ ------ ------ ------
+ ------
File                           stmt   bran   cond    sub    pod   time
+  total
---------------------------- ------ ------ ------ ------ ------ ------
+ ------
junk8.pl                      100.0   50.0    n/a  100.0    n/a  100.0
+   85.7
Total                         100.0   50.0    n/a  100.0    n/a  100.0
+   85.7
---------------------------- ------ ------ ------ ------ ------ ------
+ ------
[download]

---

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