Utilities - Locale - setLocale() method - return result of setting new locale (instead of "true")

Tests - Locale - fix incorrectly prepared tests

src/Utilities/Locale.php

@@ -23,7 +23,7 @@ class Locale
      *                             setting. It's the same constant as required by setlocale() function.
      * @param string $languageCode Language code, in ISO 639-1 format. Short form of the locale, e.g. "fr".
      * @param string $countryCode  (optional) Country code, in ISO 3166-1 alpha-2 format, e.g. "FR"
-     * @return bool
+     * @return false|string
      *
      * Available categories (values of $category argument):
      * - LC_ALL for all of the below
@@ -57,9 +57,8 @@ class Locale
         }
 
         $localeLongForm = self::getLongForm($languageCode, $countryCode);
-        setlocale($category, $localeLongForm);
 
-        return true;
+        return setlocale($category, $localeLongForm);
     }
 
     /**