diff --git a/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php b/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php
index 906e74b..8608500 100644
--- a/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php
@@ -240,4 +240,19 @@ public function testSystemCompactLink() {
$this->assertTrue($result, '"' . $element['name'] . '" is rendered correctly by drupal_render().');
}
+ /**
+ * Tests system #type 'details'.
+ */
+ public function testDetails() {
+ // Basic Details element,
+ // with "less than (<) or greater than (>)" in title, not being sanitized.
+ $this->assertElements([
+ '#type' => 'details',
+ '#title' => 'Drupal test',
+ ],
+ "\n Drupal test
\n \n \n \n \n",
+ "#type 'details' with title not sanitized"
+ );
+ }
+
}