7 files changed, 94 insertions, 7 deletions
diff --git a/core/tests/Drupal/Tests/Composer/Plugin/Unpack/Functional/UnpackRecipeTest.php b/core/tests/Drupal/BuildTests/Composer/Plugin/Unpack/Functional/UnpackRecipeTest.php
index b74349256892..1397a78cf694 100644
--- a/core/tests/Drupal/Tests/Composer/Plugin/Unpack/Functional/UnpackRecipeTest.php
+++ b/core/tests/Drupal/BuildTests/Composer/Plugin/Unpack/Functional/UnpackRecipeTest.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace Drupal\Tests\Composer\Plugin\Unpack\Functional;
+namespace Drupal\BuildTests\Composer\Plugin\Unpack\Functional;
 
 use Composer\InstalledVersions;
 use Composer\Util\Filesystem;
diff --git a/core/tests/Drupal/KernelTests/Core/Render/Element/PluginAlterTest.php b/core/tests/Drupal/KernelTests/Core/Render/Element/PluginAlterTest.php
index 7ad8afa75be6..c300cd4c019f 100644
--- a/core/tests/Drupal/KernelTests/Core/Render/Element/PluginAlterTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Render/Element/PluginAlterTest.php
@@ -23,7 +23,7 @@ class PluginAlterTest extends KernelTestBase {
     $info_manager = $this->container->get('plugin.manager.element_info');
     $this->assertArrayHasKey('weight', $info_manager->getDefinitions());
 
-    // @see element_info_test_element_plugin_alter()
+    // @see ElementInfoTestHooks::elementPluginAlter().
     $this->container->get('state')->set('hook_element_plugin_alter:remove_weight', TRUE);
     // The definition will be cached.
     $this->assertArrayHasKey('weight', $info_manager->getDefinitions());
@@ -33,4 +33,27 @@ class PluginAlterTest extends KernelTestBase {
     $this->assertArrayNotHasKey('weight', $info_manager->getDefinitions());
   }
 
+  /**
+   * Tests hook_element_plugin_alter().
+   */
+  public function testPluginClassSwap(): void {
+    $info_manager = $this->container->get('plugin.manager.element_info');
+    $test_details = [
+      '#type' => 'details',
+      '#title' => 'Title',
+      '#description' => 'Description',
+      '#open' => TRUE,
+    ];
+
+    // @see ElementInfoTestHooks::elementPluginAlter().
+    $expected = [
+      'class' => 'Drupal\element_info_test\Render\Element\Details',
+      'provider' => 'element_info_test',
+      'id' => 'details',
+    ];
+    $this->assertEquals($expected, $info_manager->getDefinitions()['details']);
+    \Drupal::service('renderer')->renderRoot($test_details);
+    $this->assertArrayHasKey('#custom', $test_details);
+  }
+
 }
diff --git a/core/tests/Drupal/KernelTests/Core/Render/Element/WeightTest.php b/core/tests/Drupal/KernelTests/Core/Render/Element/WeightTest.php
index 00b7948f2a81..e36da16d9028 100644
--- a/core/tests/Drupal/KernelTests/Core/Render/Element/WeightTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Render/Element/WeightTest.php
@@ -8,6 +8,7 @@ use Drupal\Core\Form\FormState;
 use Drupal\Core\Render\Element\Number;
 use Drupal\Core\Render\Element\Select;
 use Drupal\Core\Render\Element\Weight;
+use Drupal\Core\Render\ElementInfoManagerInterface;
 use Drupal\element_info_test\ElementInfoTestNumberBuilder;
 use Drupal\KernelTests\KernelTestBase;
 
@@ -40,7 +41,7 @@ class WeightTest extends KernelTestBase {
     $form_state = new FormState();
     $complete_form = [];
 
-    $element_object = new Weight([], 'weight', []);
+    $element_object = new Weight([], 'weight', [], elementInfoManager: $this->createStub(ElementInfoManagerInterface::class));
     $info = $element_object->getInfo();
     $element += $info;
 
diff --git a/core/tests/Drupal/Tests/Core/Render/Element/HtmlTagTest.php b/core/tests/Drupal/Tests/Core/Render/Element/HtmlTagTest.php
index d0c09e97fc53..8490a5c0876e 100644
--- a/core/tests/Drupal/Tests/Core/Render/Element/HtmlTagTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/Element/HtmlTagTest.php
@@ -6,6 +6,7 @@ namespace Drupal\Tests\Core\Render\Element;
 
 use Drupal\Core\Render\Markup;
 use Drupal\Tests\Core\Render\RendererTestBase;
+use Drupal\Core\Render\ElementInfoManagerInterface;
 use Drupal\Core\Render\Element\HtmlTag;
 
 /**
@@ -18,7 +19,7 @@ class HtmlTagTest extends RendererTestBase {
    * @covers ::getInfo
    */
   public function testGetInfo(): void {
-    $htmlTag = new HtmlTag([], 'test', 'test');
+    $htmlTag = new HtmlTag([], 'test', 'test', elementInfoManager: $this->createStub(ElementInfoManagerInterface::class));
     $info = $htmlTag->getInfo();
     $this->assertArrayHasKey('#pre_render', $info);
     $this->assertArrayHasKey('#attributes', $info);
diff --git a/core/tests/Drupal/Tests/Core/Render/Element/ModernRenderElementTest.php b/core/tests/Drupal/Tests/Core/Render/Element/ModernRenderElementTest.php
new file mode 100644
index 000000000000..c91b74f8c0a4
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Render/Element/ModernRenderElementTest.php
@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\Core\Render\Element;
+
+use Drupal\Component\Plugin\Factory\FactoryInterface;
+use Drupal\Core\Render\Element;
+use Drupal\Core\Render\Element\Textfield;
+use Drupal\Core\Render\ElementInfoManager;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\Core\Render\Element\RenderElementBase
+ * @group Render
+ */
+class ModernRenderElementTest extends UnitTestCase {
+
+  public function testChildren(): void {
+    $factory = $this->createMock(FactoryInterface::class);
+    $elementInfoManager = new class ($factory) extends ElementInfoManager {
+
+      public function __construct(protected $factory) {}
+
+    };
+    $factory->expects($this->any())
+      ->method('createInstance')
+      ->willReturnCallback(fn () => new Textfield([], '', NULL, $elementInfoManager));
+    // If the type is not given ::fromRenderable presumes "form" and uses the
+    // plugin discovery to find which class provides the form element. This
+    // test does not set up discovery so some type must be provided.
+    $element = ['#type' => 'ignored by the mock factory'];
+    $elementObject = $elementInfoManager->fromRenderable($element);
+    for ($i = 0; $i <= 2; $i++) {
+      $child = [
+        '#type' => 'ignored by the mock factory',
+        '#test' => $i,
+      ];
+      $elementObject->addChild("test$i", $child);
+      // addChild() takes the $child render array by reference and stores a
+      // reference to it in the render object. To avoid modifying the
+      // previously created render object when reusing the $child variable,
+      // unset() it to break the reference before reassigning.
+      unset($child);
+    }
+    foreach ([1 => ['test0', 'test1', 'test2'], 2 => ['test0', 'test2']] as $delta => $expectedChildrenKeys) {
+      $i = 0;
+      foreach ($elementObject->getChildren() as $name => $child) {
+        $this->assertSame($name, "test$i");
+        $this->assertSame($i, $child->test);
+        $i += $delta;
+      }
+      $this->assertSame(Element::children($elementObject->toRenderable()), $expectedChildrenKeys);
+      // The first iteration tests removing an existing child. The second
+      // iteration tests removing a nonexistent child.
+      $elementObject->removeChild('test1');
+    }
+  }
+
+}
diff --git a/core/tests/Drupal/Tests/Core/Render/Element/TableSelectTest.php b/core/tests/Drupal/Tests/Core/Render/Element/TableSelectTest.php
index fc58c1db4efe..7acfef4ca509 100644
--- a/core/tests/Drupal/Tests/Core/Render/Element/TableSelectTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/Element/TableSelectTest.php
@@ -7,6 +7,7 @@ namespace Drupal\Tests\Core\Render\Element;
 use Drupal\Core\Form\FormState;
 use Drupal\Core\Link;
 use Drupal\Core\Render\Element\Tableselect;
+use Drupal\Core\Render\ElementInfoManagerInterface;
 use Drupal\Core\StringTranslation\TranslatableMarkup;
 use Drupal\Core\Url;
 use Drupal\Tests\UnitTestCase;
@@ -25,7 +26,7 @@ class TableSelectTest extends UnitTestCase {
     $form_state = new FormState();
     $complete_form = [];
 
-    $element_object = new Tableselect([], 'table_select', []);
+    $element_object = new Tableselect([], 'table_select', [], elementInfoManager: $this->createStub(ElementInfoManagerInterface::class));
     $info = $element_object->getInfo();
     $element += $info;
 
@@ -50,7 +51,7 @@ class TableSelectTest extends UnitTestCase {
     $form_state = new FormState();
     $complete_form = [];
 
-    $element_object = new Tableselect([], 'table_select', []);
+    $element_object = new Tableselect([], 'table_select', [], elementInfoManager: $this->createStub(ElementInfoManagerInterface::class));
     $info = $element_object->getInfo();
     $element += $info;
 
diff --git a/core/tests/Drupal/Tests/Core/Theme/Icon/IconTest.php b/core/tests/Drupal/Tests/Core/Theme/Icon/IconTest.php
index 2c67cf9193fb..d1a6e6433407 100644
--- a/core/tests/Drupal/Tests/Core/Theme/Icon/IconTest.php
+++ b/core/tests/Drupal/Tests/Core/Theme/Icon/IconTest.php
@@ -5,6 +5,7 @@ declare(strict_types=1);
 namespace Drupal\Tests\Core\Theme\Icon;
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Core\Render\ElementInfoManagerInterface;
 use Drupal\Core\Render\Element\Icon;
 use Drupal\Core\Template\Attribute;
 use Drupal\Core\Theme\Icon\IconDefinition;
@@ -41,7 +42,7 @@ class IconTest extends UnitTestCase {
    * Test the Icon::getInfo method.
    */
   public function testGetInfo(): void {
-    $icon = new Icon([], 'test', 'test');
+    $icon = new Icon([], 'test', 'test', elementInfoManager: $this->createStub(ElementInfoManagerInterface::class));
     $info = $icon->getInfo();
 
     $this->assertArrayHasKey('#pre_render', $info);