Add method to validate credentials

Author: m1k3lm

src/BuilderAbstract.php

@@ -23,9 +23,11 @@ public function __construct($merchant_id)
 
     public static abstract function getPreviousOrders($customerID);
 
-    public static function integerPrice($price)
+    public static function integerPrice(int $price)
     {
-        return intval(round(self::$centsPerWhole * (float) $price));
+        return is_numeric($price)?
+            intval(round(self::$centsPerWhole * (float) $price)):
+            0;
     }
 
     protected static function dateOrBlank($date)

src/Client.php

@@ -38,6 +38,14 @@ public function __construct($user = null, $password = null, $endpoint = null, $d
         $this->_user_agent = Helper::notNull(self::$user_agent, 'cURL php ' . phpversion());
     }
 
+    public function isValidAuth()
+    {
+        $this->initCurl($this->_endpoint . '/orders');
+        curl_setopt($this->ch, CURLOPT_CUSTOMREQUEST, 'GET');
+        $this->sendRequest();
+        return $this->status != 401; 
+    }
+
     public function startSolicitation($order)
     {
         if ( ! $this->qualifyForSolicitation($order) && ! $this->_debug) {