PHP - Php Unit Testing, Practical Uses In Small Projects?

<?php

/*
 * Development API Key
 * @since 1.0
 *
 * Rate Limit(s):
 * 10 request(s) every 10 second(s)
 * 500 request(s) every 10 minute(s)
 */
define( "__API_KEY__" , "---------------------------------" );

require_once dirname( dirname(__FILE__) ) . "\\settings.php";

class API
{

    // If successfull it returns an object from the url that's passed to this function.	
    private function api_call($url)
    {
	$result = null; // end result

        // Create a new curl handle.
        $ch = curl_init();

        curl_setopt($ch , CURLOPT_URL, "https://" . $url . "?api_key=" . __RIOT_API_KEY__); // set the URL
        curl_setopt($ch , CURLOPT_RETURNTRANSFER , true  ); // return the transfer as a string of the return value
        curl_setopt($ch , CURLOPT_SSL_VERIFYPEER , false ); // turn off ssl certificate verification

        // Execute the api call
        $response = curl_exec($ch);
        // Get info to analyze the result
        $ci = curl_getinfo($ch);

        $httpcode = $ci["http_code"];

        // If a curl error occured
        if(curl_errno($ch) || ($httpcode != "200"))
        {
            $die  = "Curl Error Code: "    . $httpcode       . "<br/>";
            $die .= "Curl Error Message: " . curl_errno($ch) . "<br/>";
            $die .= "Curl URL: "           . $ci["url"]      . "<br/>";
            die($die);
        } else {

            // Check if the api call we made was valid

            $response = json_decode($response, true);

            // If our response is an array check if it's an error response
            if(is_array($response))
            {
                $error_key = "status";
                if(array_key_exists($error_key, $response))
                {
                    $er = $response[$error_key];
                    $die  = "API Error Message: " . $er["message"]     . "<br/>";
                    $die .= "API Error Code: "    . $er["status_code"] . "<br/>";
                    die($die);
                }
            }

            // Our response is a valid object
            $result = $response;
    }

    private function sanitize_url($url)
    {
        // removes all whitespaces
        return trim(preg_replace( '/\s+/','',$url));
    }

    private function regional_endpoints()
    {
        static $regionini;

        if(is_null($regionini))
            $regionini = parse_ini_file(INI_REGIONAL_ENDPOINTS, true);

        return $regionini;
    }

    private function region_host($shortcode)
    {
        /*
         * regionalendpoints.ini
         * @since 1.0
         *
         * [SHORTCODE]
         * Description=<region_description>
         * Host=<host_url>
         */
        return $this->regional_endpoints()[strtoupper($shortcode)]["Host"];
    }

    public  function region_description($shortcode)
    {
        /*
        * regionalendpoints.ini
        * @since 1.0
        *
        * [SHORTCODE]
        * Description=<region_description>
        * Host=<host_url>
        */
        return $this->regional_endpoints()[strtoupper($shortcode)]["Description"];
    }

    public function api_object_by_name($name, $region)
    {
        /*
         * @Description: Get summoner objects mapped by standardized summoner name for a given list of summoner names.
         *
         *
         * @Returns: Map[string, SummonerDto]
         *
         * Object
         * ------------------------------------------------------------------------------------------------------
         * Name             Data Type          Description
         * ------------------------------------------------------------------------------------------------------
         * id	            long	           ID.
         * name	            string	           Name.
         * profileIconId    int                    ID of the summoner icon associated with the summoner.
         * revisionDate	    long	           Date summoner was last modified specified as epoch milliseconds.
         * Level            long	           Level associated with the summoner.
         */

         $api_url = "%s/api/col/%s/v1.4/obj/by-name/%s";

        return $this->api_call(sprintf($api_url,
            $this->region_host($region),
            strtolower($region),
            $this->sanitize_url($name)));
    }

}

<?php

include dirname(__FILE__) . "\\class-riotapi.php";

define( "SUMMONER_NAME" , 0 );
define( "SUMMONER_ID"   , 1 );

class Summoner
{

    private $riotapi        = null;

    private $summoner       = null;
    private $arr_summoners  = null;
    private $region         = null;


    public function __construct()
    {
        // Create our riot api object
        $this->riotapi = new RiotAPI();
    }


    public function summoner_exists($summoners, $region, $type = SUMMONER_NAME)
    {
        static $eoa; // end of array

        // If our array of summoners is empty or we have reached the end of the array.
        if( empty($this->arr_summoners) || $eoa )
        {
            // Get an array of summoner information from the riot api based on the type of information
            // supplied.
            switch($type)
            {
                case SUMMONER_NAME :
                    $this->arr_summoners = $this->riotapi->api_summoner_by_name($summoners, $this->region = $region);
                    break;

                case SUMMONER_ID :
                    $this->arr_summoners = $this->riotapi->api_summoner_by_id($summoners, $this->region = $region);
                    break;
            }

            // If our array of summoners isn't empty.
            if( !empty($this->arr_summoners) )
            {
                // Set our current summoner the first element in the array.
                $this->summoner = reset($this->arr_summoners);
            } else {
                // We failed to acquire any summoner information so return false.
                return false;
            }

            $eoa = false;

        } else {

            // If we have not reached the end of the summoners array set our current
            // summoner to the next element.
            $next = next($this->arr_summoners);

            // Have we reached the end of the array?
            if( $next ) {
                // No. Set our current summoner to the next element.
                $this->summoner = $next;
            } else {
                // Yes. Set our end of array variable to true.
                $eoa = true;
                // End the loop
                return false;
            }

        }

        return true;
    }


    public function summoner_id()
    {
        return $this->summoner["id"];
    }


    public function summoner_name()
    {
        return $this->summoner["name"];
    }


    public function summoner_profile_icon_id()
    {
        return $this->summoner["profileIconId"];
    }


    public function summoner_last_updated()
    {
        return $this->summoner["revisionDate"];
    }


    public function summoner_level()
    {
        return $this->summoner["summonerLevel"];
    }


    public function summoner_mastery_pages()
    {
        return $this->riotapi->api_summoner_masteries($this->summoner_id(),
            $this->region)[$this->summoner_id()]["pages"];
    }

}

<?php

require_once "settings.php";
include DIR_INCLUDE . "class-summoner.php";

function summoner_exists($summoners, $region = "NA", $type = SUMMONER_NAME)
{
    global $cs;
    if(!isset($cs)){
        $cs = new Summoner();
    }
    return $cs->summoner_exists($summoners, $region, $type);
}

function summoner_name()
{
    global $cs;
    if(isset($cs)){
        echo $cs->summoner_name();
    }
}

?>

<?php include "functions.php"; ?>
<html xmlns="http://www.w3.org/1999/xhtml">
<body>

<?php while(summoner_exists("cyllo")) : ?>

    <div>Summoner Name: <?php summoner_name(); ?></div>
    <div>Summoner ID: <?php summoner_id(); ?></div>
    <div>Summoner Profile icon ID: <?php summoner_profile_icon_id(); ?></div>
    <div>Last Updated: <?php summoner_last_updated(); ?></div>
    <div>Summoner Level: <?php summoner_level(); ?></div>

    <div>
        <?php mastery_pages(); ?>
    </div>

<?php endwhile; ?>
</body>
</html>

I need to create the unique SKU (Stock Keeping Unit) name for each products mixed with
product.id,product.name,product.category and product.brand. There is no problem to do it,

i.e.: SKU for a product with

id=13,
name=Bio Clean green and
category=INSECTS KILLERS
brand=HARPIC

becomes : BI-IKHA0013

This is how I tried:

$inm = "Bio Clean green500ml";
$cnm = "INSECTS KILLERS";
$bnm = "HARPIC ";

echo SKU_gen($inm, $cnm,$bnm,20).'<br>';


function SKU_gen($pname, $cat=null, $brand=null, $id = null, $l = 2){
    $results = ''; // empty string

    $str1 = array_shift(explode(' ',$pname));
    $str1 = strtoupper(substr($str1, 0, $l));

    $str2 = array_shift(explode(' ',$cat));
    $str2 = strtoupper(substr($str2, 0, $l));

    $str3 = array_shift(explode(' ',$brand));
    $str3 = strtoupper(substr($str3, 0, $l));

    $id = str_pad($id , 4, 0, STR_PAD_LEFT);

    $results .= "{$str1}-{$str2}{$str3}{$id}";
    return $results;
}

But this function is not working as expected when category of brand values become NULL.