Issue #3240888 by andypost, alexpott: Using Prophecy to implement Serializable will cause deprecations on PHP 8.1

core/tests/Drupal/Tests/Core/Entity/EntityTypeTest.php

@@ -7,7 +7,7 @@ use Drupal\Core\Entity\Entity\EntityFormMode;
 use Drupal\Core\Entity\EntityType;
 use Drupal\Core\Entity\EntityTypeInterface;
 use Drupal\Core\StringTranslation\TranslatableMarkup;
-use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\Core\StringTranslation\TranslationManager;
 use Drupal\Tests\UnitTestCase;
 
 /**
@@ -515,10 +515,7 @@ class EntityTypeTest extends UnitTestCase {
   public function testIsSerializable() {
     $entity_type = $this->setUpEntityType([]);
 
-    $translation = $this->prophesize(TranslationInterface::class);
-    $translation->willImplement(\Serializable::class);
-    $translation->serialize()->willThrow(\Exception::class);
-    $translation_service = $translation->reveal();
+    $translation_service = new UnserializableTranslationManager();
     $translation_service->_serviceId = 'string_translation';
 
     $entity_type->setStringTranslation($translation_service);
@@ -528,3 +525,23 @@ class EntityTypeTest extends UnitTestCase {
   }
 
 }
+
+/**
+ * Test class.
+ */
+class UnserializableTranslationManager extends TranslationManager {
+
+  /**
+   * Constructs a UnserializableTranslationManager object.
+   */
+  public function __construct() {
+  }
+
+  /**
+   * @return array
+   */
+  public function __serialize(): array {
+    throw new \Exception();
+  }
+
+}

core/tests/Drupal/Tests/Core/TempStore/SharedTempStoreTest.php

@@ -355,12 +355,9 @@ class SharedTempStoreTest extends UnitTestCase {
    */
   public function testSerialization() {
     // Add an unserializable request to the request stack. If the tempstore
-    // didn't use DependencySerializationTrait, the exception would be thrown
+    // didn't use DependencySerializationTrait, an exception would be thrown
     // when we try to serialize the tempstore.
-    $request = $this->prophesize(Request::class);
-    $request->willImplement('\Serializable');
-    $request->serialize()->willThrow(new \LogicException('Oops!'));
-    $unserializable_request = $request->reveal();
+    $unserializable_request = new UnserializableRequest();
 
     $this->requestStack->push($unserializable_request);
     $this->requestStack->_serviceId = 'request_stack';
@@ -427,3 +424,17 @@ class SharedTempStoreTest extends UnitTestCase {
   }
 
 }
+
+/**
+ * A class for testing.
+ */
+class UnserializableRequest extends Request {
+
+  /**
+   * @return array
+   */
+  public function __serialize(): array {
+    throw new \LogicException('Oops!');
+  }
+
+}