Hi Dallaylaen,

Well, it may be because I am grumpy as always at this time of year, but to me it seems that you are trying to make things too shiny.

I prefer to use Lego bricks rather than modelling clay. As soon as you get your testing function just right, Murphy's Law says you will encounter data that doesn't fit. I would test your condition like this:

use strict; use warnings;
use Test::More;

my @data = (
    { id =>   1, start => 2, end => 3 },
    { id =>   2, start => 3, end => 4 },
    { id =>   3, start => 4, end => 5 }, # fail
    { id =>  42, start => 6, end => 7 },
    { id => 666, start => 7, end => 8 },
    { id => 999, start => 8, end => 9 },
);

for ( 0 .. $#data - 1 ) {
    is( $data[ $_ + 1 ]->{'start'}, $data[ $_ ]->{'end'}, "$data[ $_ ]
+->{'id'} sequence" );
}

done_testing;
__END__
[download]

1206160.pl .. 1/? 
#   Failed test '3 sequence'
#   at 1206160.pl line 18.
#          got: '6'
#     expected: '5'
# Looks like you failed 1 test of 5.
1206160.pl .. Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/5 subtests 

Test Summary Report
-------------------
1206160.pl (Wstat: 256 Tests: 5 Failed: 1)
  Failed test:  3
  Non-zero exit status: 1
Files=1, Tests=5,  0 wallclock secs ( 0.03 usr  0.00 sys +  0.04 cusr 
+ 0.01 csys =  0.08 CPU)
Result: FAIL
[download]

Or maybe like this .... Edit: as ikegami revealed the below is buggy. (emits a warning if number of list elements is not even):

se strict; use warnings;
use Test::More;
use List::Util 'pairfirst';

my @data = (
    { id =>   1, start => 2, end => 3 },
    { id =>   2, start => 3, end => 4 },
    { id =>   3, start => 4, end => 5 }, # fail
    { id =>  42, start => 6, end => 7 },
    { id => 666, start => 7, end => 8 },
    { id => 999, start => 8, end => 9 },
);

my @failed = pairfirst { $a->{'end'} ne $b->{'start'} } @data;
is( @failed, undef, 'sequencing' )
  or diag sprintf 'ID %s and ID %s are not sequential', map { $_->{'id
+'} } @failed;

done_testing;
__END__
[download]

prove 1206160.pl 

1206160.pl .. 1/? 
#   Failed test 'sequencing'
#   at 1206160.pl line 16.
#          got: '2'
#     expected: undef
# ID 3 and ID 42 are not sequential
# Looks like you failed 1 test of 1.
1206160.pl .. Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/1 subtests 

Test Summary Report
-------------------
1206160.pl (Wstat: 256 Tests: 1 Failed: 1)
  Failed test:  1
  Non-zero exit status: 1
Files=1, Tests=1,  0 wallclock secs ( 0.02 usr  0.00 sys +  0.06 cusr 
+ 0.00 csys =  0.08 CPU)
Result: FAIL
[download]

Hope this helps, and Happy Merry!