Lowercase non-ASCII words in words()

src/Extensions/TextExtension.php

@@ -85,7 +85,15 @@ public function words(int $words = 3): string
         $words = $this->wordsAsArray($words);
 
         // Remove any uppercase / comma / dots
-        return strtolower(preg_replace('/[.,]/', '', implode(' ', $words)));
+        $words = preg_replace('/[.,]/', '', implode(' ', $words));
+
+        if (function_exists('mb_strtolower')) {
+            return mb_strtolower($words);
+        }
+
+        trigger_error('You do not have the `mbstring` extension enabled; FakerPHP might not handle uncommon characters correctly.', E_USER_WARNING);
+
+        return strtolower($words);
     }
 
     public function sentencesAsArray(int $sentences = 3): array

tests/Unit/Extensions/TextExtensionTest.php

@@ -30,6 +30,14 @@ public function testWordsWithDefaultValue(): void
         }
     }
 
+    public function testWordsLowercasesNonAsciiCharacters(): void
+    {
+        $extension = new \Xefi\Faker\Extensions\TextExtension(new \Random\Randomizer());
+        (new ReflectionClass($extension))->getProperty('paragraphs')->setValue($extension, [[['Ёлка', 'Écrit', 'Über.']]]);
+
+        $this->assertEqualsCanonicalizing(['ёлка', 'écrit', 'über'], explode(' ', $extension->words(3)));
+    }
+
     public static function wordsProvider()
     {
         return [