--- /dev/null
+<?php
+
+namespace Drupal\Tests\Core\Render;
+
+use Drupal\Component\Utility\Html;
+
+/**
+ * @coversDefaultClass \Drupal\Core\Render\PlaceholderGenerator
+ * @group Render
+ */
+class PlaceholderGeneratorTest extends RendererTestBase {
+
+ /**
+ * The tested placeholder generator.
+ *
+ * @var \Drupal\Core\Render\PlaceholderGenerator
+ */
+ protected $placeholderGenerator;
+
+ /**
+ * @covers ::createPlaceholder
+ * @dataProvider providerCreatePlaceholderGeneratesValidHtmlMarkup
+ *
+ * Ensure that the generated placeholder markup is valid. If it is not, then
+ * simply using DOMDocument on HTML that contains placeholders may modify the
+ * placeholders' markup, which would make it impossible to replace the
+ * placeholders: the placeholder markup in #attached versus that in the HTML
+ * processed by DOMDocument would no longer match.
+ */
+ public function testCreatePlaceholderGeneratesValidHtmlMarkup(array $element) {
+ $build = $this->placeholderGenerator->createPlaceholder($element);
+
+ $original_placeholder_markup = (string)$build['#markup'];
+ $processed_placeholder_markup = Html::serialize(Html::load($build['#markup']));
+
+ $this->assertEquals($original_placeholder_markup, $processed_placeholder_markup);
+ }
+
+ /**
+ * @return array
+ */
+ public function providerCreatePlaceholderGeneratesValidHtmlMarkup() {
+ return [
+ 'multiple-arguments' => [['#lazy_builder' => ['Drupal\Tests\Core\Render\PlaceholdersTest::callback', ['foo', 'bar']]]],
+ 'special-character-&' => [['#lazy_builder' => ['Drupal\Tests\Core\Render\PlaceholdersTest::callback', ['foo&bar']]]],
+ 'special-character-"' => [['#lazy_builder' => ['Drupal\Tests\Core\Render\PlaceholdersTest::callback', ['foo"bar']]]],
+ 'special-character-<' => [['#lazy_builder' => ['Drupal\Tests\Core\Render\PlaceholdersTest::callback', ['foo<bar']]]],
+ 'special-character->' => [['#lazy_builder' => ['Drupal\Tests\Core\Render\PlaceholdersTest::callback', ['foo>bar']]]],
+ ];
+
+ }
+
+}