chore: adds missing tests

src/Support/Str.php

@@ -14,12 +14,12 @@ final class Str
      */
     public static function isRegex(string $target): bool
     {
-        if (strlen($target) < 2) {
+        if (mb_strlen($target) < 2) {
             return false;
         }
 
         // If the first and last characters are not the same, it's not a regex
-        if (($delimiter = substr($target, 0, 1)) !== substr($target, -1, 1)) {
+        if (($delimiter = mb_substr($target, 0, 1)) !== mb_substr($target, -1, 1)) {
             return false;
         }
 

tests/Unit/Support/StrTest.php

@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+use Pest\Browser\Support\Str;
+
+it('detects regex expressions', function () {
+    $regex = '/^.*$/';
+
+    $result = Str::isRegex($regex);
+
+    expect($result)->toBeTrue();
+});
+
+it('detects non-regex expressions', function () {
+    $string = 'string';
+
+    $result = Str::isRegex($string);
+
+    expect($result)->toBeFalse();
+});