More test cases

use strict;
use warnings;

use FindBin qw($Bin);
use lib $Bin;

use Test::More;
plan tests => 3;

use MyWebAPI;

use Test::Mock::Simple;
my $mock = Test::Mock::Simple->new(module => 'MyWebAPI');
$mock->add(get => sub {
    return 'Beyonce Beyonce Miley Cyrus';
});

my $w = MyWebAPI->new;

is_deeply $w->count_strings('Beyonce', 'Miley Cyrus'), 
    {
        'Beyonce'     => 2,
        'Miley Cyrus' => 1,
    };

$mock->add(get => sub {
    return 'Beyonce';
});
is_deeply $w->count_strings('Beyonce', 'Miley Cyrus'), 
    {
        Beyonce => 1,
        'Miley Cyrus' => 0,
    };

$mock->add(get => sub {
    return '';
});
is_deeply $w->count_strings('Beyonce', 'Miley Cyrus'), 
    {
        Beyonce => 0,
        'Miley Cyrus' => 0,
    };