#!perl
use strict;
use warnings;
use Test::More;
use Data::Dumper;

my @cities = qw(
    Berlin 
    Budapest
    London 
    Paris 
    Praha
);

# Data driven tests:
my @grepper_tests = (
    {
        wanted_regex => qr/B/,
        expected_nr_found => 2,
    },
    # many more tests to come here...
);
my @found_cities;
my $expected_nr_found;

for my $cur_test (@grepper_tests) {
    my $wanted_regex = $cur_test->{wanted_regex};
    cmp_ok(ref($wanted_regex), 'eq', 'Regexp', 'Regex type ok: ' . $wanted_regex);
    $expected_nr_found = $cur_test->{expected_nr_found};
    @found_cities = grep $wanted_regex, @cities;
    cmp_ok(scalar(@found_cities), '==', $expected_nr_found,
        "I have found: " . join(", ", @found_cities));
}

# Single written tests:
@found_cities = grep /B/, @cities;
$expected_nr_found = 2;
cmp_ok(scalar(@found_cities), '==', $expected_nr_found,
        "I have found: " . join(", ", @found_cities));

# as soon as the regex is in a variable the whole searched array
# is the result
my $wanted_regex = qr/B/;
cmp_ok(ref($wanted_regex), 'eq', 'Regexp', 'Regex type ok: ' . $wanted_regex);
@found_cities = grep $wanted_regex, @cities;
$expected_nr_found = 2;
cmp_ok(scalar(@found_cities), '==', 2,
        "I have found: " . join(", ", @found_cities));

done_testing();

##</code><code>##

~/perltest_regex_in_array$ perl 100_regex_in_array.pl
ok 1 - Regex type ok: (?^:B)
not ok 2 - I have found: Berlin, Budapest, London, Paris, Praha
#   Failed test 'I have found: Berlin, Budapest, London, Paris, Praha'
#   at 100_regex_in_array.pl line 31.
#          got: 5
#     expected: 2
ok 3 - I have found: Berlin, Budapest
ok 4 - Regex type ok: (?^:B)
not ok 5 - I have found: Berlin, Budapest, London, Paris, Praha
#   Failed test 'I have found: Berlin, Budapest, London, Paris, Praha'
#   at 100_regex_in_array.pl line 47.
#          got: 5
#     expected: 2
1..5
# Looks like you failed 2 tests of 5.