#!/usr/bin/perl 

use strict;
use warnings;

use File::Spec;
use Getopt::Long;

my $dir      = ".";
my $test_num = 10;
my $step     = 10;

GetOptions(
    "dir=s"   => \$dir,
    "start=i" => \$test_num,
    "step=i"  => \$step,
    "dry"     => \my $dry_run,
    "svn"     => \my $svn,
);

unless ( -d $dir ) {
    die "I cannot find the directory ($dir)";
}

my $tests = File::Spec->catfile( $dir, "*.t" );
if ( $tests =~ /^(.+)\*.t$/ ) {
    $dir = $1;    # now we have the directory with the separator
}

my @tests = glob $tests;
unless (@tests) {
    die "No tests found in ($tests)";
}

{
    no warnings 'numeric';
    @tests =
      map  { s/^\d+//; $_ }
      sort { $a <=> $b }
      map  { s{^$dir(\d+)/}{$1$dir$1}; $_ }
      grep { /^\Q$dir\E\d+/ } 
        @tests;    # only take numbered tests
}

unless ($dry_run) {
    print <<"    END_WARNING";
    Warning:  this is not a dry run and you're really going to
    renumber the tests.  Are you sure you want to continue?  (y/n)
    END_WARNING
    my $response = <STDIN>;
    unless ($response =~ /^[Yy]/) {
        print "Answer was not 'y' or 'Y'.  Aborting";
        exit(0);
    }
}

my $digits = length( $test_num + ( $step * @tests ) );

$test_num = $test_num - $step;           # because of how we handle th
+e s///
foreach my $test (@tests) {
    my $new_name = $test;
    $new_name =~ s{(?<=\Q$dir\E)\d+}
                  { 
                    $test_num += $step;
                    sprintf "%0${digits}d", $test_num;
                  }e;

    next if $new_name eq $test;
    my @command = ( "mv", $test, $new_name );
    if ($svn) {
        unshift @command, "svn";
    }
    if ($dry_run) {
        print "@command\n";
    }
    else {
        system(@command);
    }
}
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