#! /usr/bin/perl
use strict;
use warnings;

while ( my $line = <DATA> ) {
        chomp $line;

        # split into: $1: test result, $2: test number, $3 - other string
        if ( $line =~ m/^(.+?)\s+(\d+)\s+-\s+(.+)/ ) {
                printf "%-6s %3d - %s\n", $1, $2, $3;
        }
        # other lines are printed as they are...
        else {
                print $line, "\n";
        }
}

__DATA__
ok 1 - bla bla bla
ok 2 - foo
not ok 3 - bar
...
not ok 12 - beispiel

ok       1 - bla bla bla
ok       2 - foo
not ok   3 - bar
...
not ok  12 - beispiel