diff --git a/core/modules/serialization/tests/src/Unit/Normalizer/UriNormalizerTest.php b/core/modules/serialization/tests/src/Unit/Normalizer/UriNormalizerTest.php
index 0986796..23f55c8 100644
--- a/core/modules/serialization/tests/src/Unit/Normalizer/UriNormalizerTest.php
+++ b/core/modules/serialization/tests/src/Unit/Normalizer/UriNormalizerTest.php
@@ -9,13 +9,10 @@
 use Symfony\Component\Serializer\Serializer;
 
 /**
- * @coversDefaultClass \Drupal\serialization\Normalizer\UriItemNormalizer
- *
- *
+ * Tests the normalizer for URI field items.
  *
- * Drupal\Core\TypedData\Plugin\DataType\Uri
+ * @coversDefaultClass \Drupal\serialization\Normalizer\UriItemNormalizer
  *
- * Drupal\Core\Field\Plugin\Field\FieldType\UriItem
  * @group serialization
  */
 class UriNormalizerTest extends UnitTestCase {
@@ -38,26 +35,27 @@ class UriNormalizerTest extends UnitTestCase {
    * {@inheritdoc}
    */
   protected function setUp() {
-    $this->normalizer = new UriItemNormalizer();
+    parent::setUp();
 
-    $this->serializer = $this->prophesize(Serializer::class);
-    $this->normalizer->setSerializer($this->serializer->reveal());
+    $this->normalizer = new UriItemNormalizer();
   }
 
   /**
    * @covers ::supportsNormalization
    * @dataProvider dataProviderUriData
    */
-  public function testSupportsNormalization($uri_data, $expected) {
-    $this->assertTrue($this->normalizer->supportsNormalization($uri_data));
+  public function testSupportsNormalization($file_uri) {
+    $uri_item = $this->prepareUriItem($file_uri);
+    $this->assertTrue($this->normalizer->supportsNormalization($uri_item->reveal()));
   }
 
   /**
    * @covers ::normalize
    * @dataProvider dataProviderUriData
    */
-  public function testNormalize($uri_data, $expected) {
-    $this->assertSame($expected, $this->normalizer->normalize($uri_data));
+  public function testNormalize($file_uri, $expected) {
+    $uri_item = $this->prepareUriItem($file_uri);
+    $this->assertSame($expected, $this->normalizer->normalize($uri_item->reveal()));
   }
 
   /**
@@ -67,7 +65,7 @@ public function dataProviderUriData() {
     $data = [];
 
     $data['uri'] = [
-      $this->prophesizeDefinition('public://some-file.pdf')->reveal(),
+      'public://some-file.pdf',
       [
         'value' => 'public://some-file.pdf',
         'url' => 'file_create_url:public://some-file.pdf',
@@ -75,7 +73,7 @@ public function dataProviderUriData() {
     ];
 
     $data['uri-null'] = [
-      $this->prophesizeDefinition(NULL)->reveal(),
+      NULL,
       [
         'value' => NULL,
       ],
@@ -84,23 +82,29 @@ public function dataProviderUriData() {
   }
 
   /**
-   * Helper to define prophecies.
+   * Prepares a URI field item for a specific file URI.
    *
    * @param string $file_uri
+   *   The file URI to prepare the URI field item for.
    *
-   * @return \Prophecy\Prophecy\ObjectProphecy
+   * @return \Prophecy\Prophecy\ProphecyInterface
+   *   A prophecy for the URI field item.
    */
-  protected function prophesizeDefinition($file_uri) {
-    $uri_prophecy = $this->prophesize(Uri::class);
-    $uri_prophecy->getValue()->willReturn($file_uri);
-    $uri = $uri_prophecy->reveal();
+  protected function prepareUriItem($file_uri) {
+    $uri_property = $this->prophesize(Uri::class);
+    $uri_property->getValue()->willReturn($file_uri);
+
+    $this->serializer = $this->prophesize(Serializer::class);
+    $this->serializer->normalize($uri_property->reveal(), NULL, [])->willReturn($file_uri);
+    $this->normalizer->setSerializer($this->serializer->reveal());
 
-    $uri_item_prophecy = $this->prophesize(UriItem::class);
-    $uri_item_prophecy->get('value')->willReturn($uri);
-    $uri_item_prophecy->getIterator()->willReturn(new \ArrayIterator(['value' => $uri]));
+    $uri_item = $this->prophesize(UriItem::class);
+    $uri_item->get('value')->willReturn($uri_property->reveal());
+    $uri_item->getIterator()->willReturn(new \ArrayIterator(['value' => $uri_property->reveal()]));
 
-    return $uri_item_prophecy;
+    return $uri_item;
   }
+
 }
 
 namespace Drupal\serialization\Normalizer;