Test attribute callbacks after cloning

tests/CloneTest.php

@@ -2,11 +2,14 @@
 
 namespace ipl\Tests\Html;
 
+use InvalidArgumentException;
 use ipl\Html\Attribute;
 use ipl\Html\Attributes;
 use ipl\Html\Form;
+use ipl\Html\FormElement\InputElement;
 use ipl\Html\FormElement\SelectElement;
 use ipl\Html\FormElement\SubmitElement;
+use ReflectionProperty;
 
 class CloneTest extends TestCase
 {
@@ -65,4 +68,34 @@ public function testCloningAttributes(): void
 
         $this->assertNotSame($original, $clone);
     }
+
+    public function testCallbacks()
+    {
+        $input = (new InputElement('text', 'text'))
+            ->setValue('original');
+        $clone = (clone $input)
+            ->setValue('clone');
+
+        $this->assertEquals('original', $this->getAttributeCallbackValue($input->getAttributes(), 'value'));
+        $this->assertEquals('clone', $this->getAttributeCallbackValue($clone->getAttributes(), 'value'));
+    }
+
+    protected function getAttributeCallbackValue(Attributes $attributes, string $name)
+    {
+        $callbacksProperty = new ReflectionProperty(get_class($attributes), 'callbacks');
+        $callbacksProperty->setAccessible(true);
+        $callbacks = $callbacksProperty->getValue($attributes);
+
+        if (isset($callbacks[$name])) {
+            $attribute = $callbacks[$name]();
+
+            if ($attribute instanceof Attribute) {
+                return $attribute->getValue();
+            }
+
+            return $attribute;
+        }
+
+        throw new InvalidArgumentException();
+    }
 }