[9.x] Do not transform JsonSerializable instances to array in HTTP client methods

src/Illuminate/Http/Client/PendingRequest.php

@@ -8,6 +8,7 @@
 use GuzzleHttp\Exception\RequestException;
 use GuzzleHttp\Exception\TransferException;
 use GuzzleHttp\HandlerStack;
+use Illuminate\Contracts\Support\Arrayable;
 use Illuminate\Http\Client\Events\ConnectionFailed;
 use Illuminate\Http\Client\Events\RequestSending;
 use Illuminate\Http\Client\Events\ResponseReceived;
@@ -747,7 +748,13 @@ protected function parseHttpOptions(array $options)
             $options[$this->bodyFormat] = $this->pendingBody;
         }
 
-        return collect($options)->toArray();
+        return collect($options)->map(function ($value, $key) {
+            if ($key === 'json' && $value instanceof JsonSerializable) {
+                return $value;
+            }
+
+            return $value instanceof Arrayable ? $value->toArray() : $value;
+        })->all();
     }
 
     /**

tests/Http/HttpClientTest.php

@@ -6,6 +6,7 @@
 use GuzzleHttp\Promise\PromiseInterface;
 use GuzzleHttp\Psr7\Response as Psr7Response;
 use Illuminate\Contracts\Events\Dispatcher;
+use Illuminate\Contracts\Support\Arrayable;
 use Illuminate\Http\Client\Events\RequestSending;
 use Illuminate\Http\Client\Events\ResponseReceived;
 use Illuminate\Http\Client\Factory;
@@ -221,6 +222,34 @@ public function jsonSerialize(): mixed
         });
     }
 
+    public function testPrefersJsonSerializableOverArrayableData()
+    {
+        $this->factory->fake();
+
+        $this->factory->asJson()->post('http://foo.com/form', new class implements JsonSerializable, Arrayable
+        {
+            public function jsonSerialize(): mixed
+            {
+                return [
+                    'attributes' => (object) [],
+                ];
+            }
+
+            public function toArray(): array
+            {
+                return [
+                    'attributes' => [],
+                ];
+            }
+        });
+
+        $this->factory->assertSent(function (Request $request) {
+            return $request->url() === 'http://foo.com/form' &&
+                $request->hasHeader('Content-Type', 'application/json') &&
+                $request->body() === '{"attributes":{}}';
+        });
+    }
+
     public function testRecordedCallsAreEmptiedWhenFakeIsCalled()
     {
         $this->factory->fake([