Add Form::yieldElementsRecursive() to fix partial validation for FormElements

src/Form.php

@@ -2,11 +2,11 @@
 
 namespace ipl\Html;
 
+use Generator;
 use ipl\Html\Contract\DefaultFormElementDecoration;
 use ipl\Html\Contract\FormDecoration;
 use ipl\Html\Contract\FormElement;
 use ipl\Html\Contract\FormSubmitElement;
-use ipl\Html\Contract\MutableHtml;
 use ipl\Html\FormDecoration\DecoratorChain;
 use ipl\Html\FormDecoration\FormDecorationResult;
 use ipl\Html\FormElement\FormElements;
@@ -354,9 +354,7 @@ public function validate()
      */
     public function validatePartial()
     {
-        $this->ensureAssembled();
-
-        foreach ($this->getElements() as $element) {
+        foreach ($this->yieldElementsRecursive($this) as $element) {
             if ($element->hasValue()) {
                 $element->validate();
             }
@@ -442,4 +440,28 @@ protected function beforeRender(): void
 
         $this->applyDecoration();
     }
+
+    /**
+     * Yield all sub form elements of $from by traversing the form elements tree recursively
+     *
+     * Recurses into nested {@see FormElements} instances instead of yielding them directly.
+     *
+     * @param Contract\FormElements $from Entry point for traversing
+     *
+     * @return Generator<FormElement>
+     */
+    protected function yieldElementsRecursive(Contract\FormElements $from): Generator
+    {
+        if ($from instanceof HtmlDocument) {
+            $from->ensureAssembled();
+        }
+
+        foreach ($from->getElements() as $element) {
+            if ($element instanceof Contract\FormElements) {
+                yield from $this->yieldElementsRecursive($element);
+            } else {
+                yield $element;
+            }
+        }
+    }
 }

tests/FormTest.php

@@ -4,6 +4,7 @@
 
 use ipl\Html\Form;
 use ipl\Html\FormElement\BaseFormElement;
+use ipl\Html\FormElement\FieldsetElement;
 use ipl\Html\Test\TestCase;
 use Psr\Http\Message\ServerRequestInterface;
 
@@ -63,6 +64,46 @@ public function testEscapeReservedChars(): void
         $this->assertSame(Form::escapeReservedChars('foo-bar123'), 'foo-bar123');
     }
 
+    public function testValidatePartialOnlyValidatesFieldsetChildrenWithAValue(): void
+    {
+        $fieldset = (new FieldsetElement('set'))
+            ->addElement('text', 'filled', ['required' => true])
+            ->addElement('text', 'empty', ['required' => true]);
+        $fieldset->getElement('filled')->setValue('value');
+
+        $form = (new Form())
+            ->addElement($fieldset)
+            ->validatePartial();
+
+        $this->assertTrue(
+            $form->getElement('set')->getElement('filled')->isValid(),
+            'Fieldset child with a value is not validated during partial validation'
+        );
+        $this->assertEmpty(
+            $form->getElement('set')->getElement('empty')->getMessages(),
+            'Empty fieldset child produces a required error during partial validation'
+        );
+    }
+
+    public function testValidatePartialRecursesIntoNestedFieldsets(): void
+    {
+        $innerFieldset = (new FieldsetElement('inner'))
+            ->addElement('text', 'deep', ['required' => true]);
+        $innerFieldset->getElement('deep')->setValue('value');
+
+        $outerFieldset = (new FieldsetElement('outer'))
+            ->addElement($innerFieldset);
+
+        $form = (new Form())
+            ->addElement($outerFieldset)
+            ->validatePartial();
+
+        $this->assertTrue(
+            $form->getElement('outer')->getElement('inner')->getElement('deep')->isValid(),
+            'Nested fieldset child with a value is not validated during partial validation'
+        );
+    }
+
     public function testFormElementsWithReservedCharsInName(): void
     {
         $form = new Form();