$ cat 790142.pl
use strict;
use warnings;

use Test::More qw(no_plan);
use Data::Dumper;
use DBI;
my $dbh = DBI->connect('DBI:Mock:', '', '');

$dbh->{'mock_add_resultset'} = {
  sql     => 'QUERY_ONE',
  results => [
    [ 'foo',        'bar' ],
    [ 'this_one',   'this_two' ],
    [ 'this_three', 'this_four' ],
  ],
};

$dbh->{'mock_add_resultset'} = {
  sql     => 'QUERY_TWO',
  results => [
    [ 'moo',      'baah' ],
    [ 'that_one',   'that_two' ],
    [ 'that_three', 'that_four' ],
  ],
};

my $sth = $dbh->prepare('QUERY_ONE');
is_deeply( $sth->fetchrow_arrayref(), [ 'this_one',   'this_two' ] );
is_deeply( $sth->fetchrow_arrayref(), [ 'this_three', 'this_four' ] );
ok( !defined $sth->fetchrow_arrayref() ); #  no more data

$sth = $dbh->prepare('QUERY_TWO');
is_deeply( $sth->fetchrow_arrayref(), [ 'that_one',   'that_two' ] );
is_deeply( $sth->fetchrow_arrayref(), [ 'that_three', 'that_four' ] );
ok( !defined $sth->fetchrow_arrayref() ); #  no more data

$sth = $dbh->prepare('QUERY_THREE');
ok( !defined $sth->fetchrow_arrayref() ); #  no matching query

__END__
 
$ perl 790142.pl
ok 1
ok 2
ok 3
ok 4
ok 5
ok 6
ok 7
1..7
$