[LiveComponent] Handle loose comparison with empty placeholder

Author: Matthieu Renard

src/LiveComponent/src/ComponentWithFormTrait.php

@@ -265,7 +265,7 @@ private function extractFormValues(FormView $formView): array
                 && $child->vars['required']
                 && !$child->vars['disabled']
                 && !$child->vars['value']
-                && !$child->vars['placeholder']
+                && (false === $child->vars['placeholder'] || null === $child->vars['placeholder'])
                 && !$child->vars['multiple']
                 && !$child->vars['expanded']
                 && $child->vars['choices']

src/LiveComponent/tests/Fixtures/Form/FormWithManyDifferentFieldsType.php

@@ -52,6 +52,13 @@ public function buildForm(FormBuilderInterface $builder, array $options)
                 ],
                 'placeholder' => 'foo',
             ])
+            ->add('choice_required_with_empty_placeholder', ChoiceType::class, [
+                'choices' => [
+                    'bar' => 2,
+                    'foo' => 1,
+                ],
+                'placeholder' => '',
+            ])
             ->add('choice_required_without_placeholder', ChoiceType::class, [
                 'choices' => [
                     'bar' => 2,

src/LiveComponent/tests/Functional/Form/ComponentWithFormTest.php

@@ -179,6 +179,7 @@ public function testHandleCheckboxChanges(): void
             'range' => '',
             'choice' => '',
             'choice_required_with_placeholder' => '',
+            'choice_required_with_empty_placeholder' => '',
             'choice_required_without_placeholder' => '2',
             'choice_expanded' => '',
             'choice_multiple' => ['2'],

src/LiveComponent/tests/Unit/Form/ComponentWithFormTest.php

@@ -44,6 +44,7 @@ public function testFormValues(): void
                 'range' => '',
                 'choice' => '',
                 'choice_required_with_placeholder' => '',
+                'choice_required_with_empty_placeholder' => '',
                 'choice_required_without_placeholder' => '2',
                 'choice_expanded' => '',
                 'choice_multiple' => ['2'],