fix: displaying "encoding error" when serializing empty strings (#1940)

Author: JulienChavee

src/Serializer/AbstractSerializer.php

@@ -216,6 +216,10 @@ protected function serializeObject($object, int $_depth = 0, array $hashes = [])
      */
     protected function serializeString(string $value): string
     {
+        if ($value === '') {
+            return '';
+        }
+
         // we always guarantee this is coerced, even if we can't detect encoding
         if ($currentEncoding = mb_detect_encoding($value, $this->mbDetectOrder)) {
             $encoded = mb_convert_encoding($value, 'UTF-8', $currentEncoding) ?: '<encoding error>';

tests/Serializer/SerializerTest.php

@@ -225,6 +225,15 @@ public function testClippingUTF8Characters(): void
         $this->assertSame(\JSON_ERROR_NONE, json_last_error());
     }
 
+    public function testEmptyString(): void
+    {
+        $serializer = $this->createSerializer();
+
+        $result = $this->invokeSerialization($serializer, '');
+
+        $this->assertSame('', $result);
+    }
+
     /**
      * @return Serializer
      */