diff --git a/core/modules/rdf/src/Tests/GetNamespacesTest.php b/core/modules/rdf/src/Tests/GetNamespacesTest.php
deleted file mode 100644
index ca46c5c..0000000
--- a/core/modules/rdf/src/Tests/GetNamespacesTest.php
+++ /dev/null
@@ -1,50 +0,0 @@
-<?php
-
-namespace Drupal\rdf\Tests;
-
-use Drupal\simpletest\WebTestBase;
-
-/**
- * Confirm that the serialization of RDF namespaces in present in the HTML
- * markup.
- *
- * @group rdf
- */
-class GetNamespacesTest extends WebTestBase {
-
-  /**
-   * Modules to enable.
-   *
-   * @var array
-   */
-  public static $modules = ['rdf', 'rdf_test_namespaces'];
-
-  /**
-   * Tests RDF namespaces.
-   */
-  public function testGetRdfNamespaces() {
-    // Fetches the front page and extracts RDFa 1.1 prefixes.
-    $this->drupalGet('');
-
-    $element = $this->xpath('//html[contains(@prefix, :prefix_binding)]', [
-      ':prefix_binding' => 'rdfs: http://www.w3.org/2000/01/rdf-schema#',
-    ]);
-    $this->assertTrue(!empty($element), 'A prefix declared once is displayed.');
-
-    $element = $this->xpath('//html[contains(@prefix, :prefix_binding)]', [
-      ':prefix_binding' => 'foaf: http://xmlns.com/foaf/0.1/',
-    ]);
-    $this->assertTrue(!empty($element), 'The same prefix declared in several implementations of hook_rdf_namespaces() is valid as long as all the namespaces are the same.');
-
-    $element = $this->xpath('//html[contains(@prefix, :prefix_binding)]', [
-      ':prefix_binding' => 'foaf1: http://xmlns.com/foaf/0.1/',
-    ]);
-    $this->assertTrue(!empty($element), 'Two prefixes can be assigned the same namespace.');
-
-    $element = $this->xpath('//html[contains(@prefix, :prefix_binding)]', [
-      ':prefix_binding' => 'dc: http://purl.org/dc/terms/',
-    ]);
-    $this->assertTrue(!empty($element), 'When a prefix has conflicting namespaces, the first declared one is used.');
-  }
-
-}
diff --git a/core/modules/rdf/src/Tests/CommentAttributesTest.php b/core/modules/rdf/tests/src/Functional/CommentAttributesTest.php
similarity index 99%
rename from core/modules/rdf/src/Tests/CommentAttributesTest.php
rename to core/modules/rdf/tests/src/Functional/CommentAttributesTest.php
index 8ca5798..5bd5ca0 100644
--- a/core/modules/rdf/src/Tests/CommentAttributesTest.php
+++ b/core/modules/rdf/tests/src/Functional/CommentAttributesTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\rdf\Tests;
+namespace Drupal\Tests\rdf\Functional;
 
 use Drupal\comment\CommentInterface;
 use Drupal\comment\CommentManagerInterface;
diff --git a/core/modules/rdf/tests/src/Functional/GetNamespacesTest.php b/core/modules/rdf/tests/src/Functional/GetNamespacesTest.php
new file mode 100644
index 0000000..93a8f4b
--- /dev/null
+++ b/core/modules/rdf/tests/src/Functional/GetNamespacesTest.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace Drupal\Tests\rdf\Functional;
+
+use Drupal\Tests\BrowserTestBase;
+
+/**
+ * Confirm that the serialization of RDF namespaces in present in the HTML
+ * markup.
+ *
+ * @group rdf
+ */
+class GetNamespacesTest extends BrowserTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = ['rdf', 'rdf_test_namespaces'];
+
+  /**
+   * Tests RDF namespaces.
+   */
+  public function testGetRdfNamespaces() {
+    // Fetches the front page and extracts RDFa 1.1 prefixes.
+    $this->drupalGet('');
+
+    $page = $this->getSession()->getPage();
+    $html = $page->find('css', 'html');
+    $prefix = $html->getAttribute('prefix');
+
+    $this->assertContains('rdfs: http://www.w3.org/2000/01/rdf-schema#', $prefix, 'A prefix declared once is displayed.');
+    $this->assertContains('foaf: http://xmlns.com/foaf/0.1/', $prefix, 'The same prefix declared in several implementations of hook_rdf_namespaces() is valid as long as all the namespaces are the same.');
+    $this->assertContains('foaf1: http://xmlns.com/foaf/0.1/', $prefix, 'Two prefixes can be assigned the same namespace.');
+    $this->assertContains('dc: http://purl.org/dc/terms/', $prefix, 'When a prefix has conflicting namespaces, the first declared one is used.');
+  }
+
+}
diff --git a/core/modules/rdf/src/Tests/ImageFieldAttributesTest.php b/core/modules/rdf/tests/src/Functional/ImageFieldAttributesTest.php
similarity index 98%
rename from core/modules/rdf/src/Tests/ImageFieldAttributesTest.php
rename to core/modules/rdf/tests/src/Functional/ImageFieldAttributesTest.php
index d4d7d35..1a6e685 100644
--- a/core/modules/rdf/src/Tests/ImageFieldAttributesTest.php
+++ b/core/modules/rdf/tests/src/Functional/ImageFieldAttributesTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\rdf\Tests;
+namespace Drupal\Tests\rdf\Functional;
 
 use Drupal\image\Entity\ImageStyle;
 use Drupal\image\Tests\ImageFieldTestBase;