diff --git a/UPGRADE.md b/UPGRADE.md
index a7d7824c10b..5b84d48a366 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,5 +1,15 @@
 # Upgrade to 3.0
 
+## BC BREAK: Remove ability to merge detached entities
+
+Merge semantics was a poor fit for the PHP "share-nothing" architecture.
+In addition to that, merging caused multiple issues with data integrity
+in the managed entity graph, which was constantly spawning more edge-case
+bugs/scenarios.
+
+The method `UnitOfWork::merge()` has been removed. The method
+`EntityManager::merge()` will throw an exception on each call.
+
 ## BC BREAK: Removed ability to partially flush/commit entity manager and unit of work
 
 The following methods don't accept a single entity or an array of entities anymore:
diff --git a/lib/Doctrine/ORM/EntityManager.php b/lib/Doctrine/ORM/EntityManager.php
index 4b6cf01d825..32e1df09c3a 100644
--- a/lib/Doctrine/ORM/EntityManager.php
+++ b/lib/Doctrine/ORM/EntityManager.php
@@ -4,13 +4,13 @@
 
 namespace Doctrine\ORM;
 
+use BadMethodCallException;
 use Doctrine\Common\EventManager;
 use Doctrine\Common\Util\ClassUtils;
 use Doctrine\DBAL\Connection;
 use Doctrine\DBAL\DriverManager;
 use Doctrine\DBAL\Exception as DBALException;
 use Doctrine\DBAL\LockMode;
-use Doctrine\Deprecations\Deprecation;
 use Doctrine\ORM\Exception\EntityManagerClosed;
 use Doctrine\ORM\Exception\InvalidHydrationMode;
 use Doctrine\ORM\Exception\ManagerException;
@@ -542,35 +542,15 @@ public function detach($entity): void
     }
 
     /**
-     * Merges the state of a detached entity into the persistence context
-     * of this EntityManager and returns the managed copy of the entity.
-     * The entity passed to merge will not become associated/managed with this EntityManager.
+     * Not supported.
      *
-     * @deprecated 2.7 This method is being removed from the ORM and won't have any replacement
+     * @param object $object
      *
-     * @param object $entity The detached entity to merge into the persistence context.
-     *
-     * @return object The managed copy of the entity.
-     *
-     * @throws ORMInvalidArgumentException
-     * @throws ORMException
+     * @psalm-return never
      */
-    public function merge($entity): object
+    public function merge($object): object
     {
-        Deprecation::trigger(
-            'doctrine/orm',
-            'https://github.com/doctrine/orm/issues/8461',
-            'Method %s() is deprecated and will be removed in Doctrine ORM 3.0.',
-            __METHOD__
-        );
-
-        if (! is_object($entity)) {
-            throw ORMInvalidArgumentException::invalidObject('EntityManager#merge()', $entity);
-        }
-
-        $this->errorIfClosed();
-
-        return $this->unitOfWork->merge($entity);
+        throw new BadMethodCallException('The merge operation is not supported.');
     }
 
     /**
diff --git a/lib/Doctrine/ORM/Mapping/Reflection/ReflectionPropertiesGetter.php b/lib/Doctrine/ORM/Mapping/Reflection/ReflectionPropertiesGetter.php
deleted file mode 100644
index c1bfe8553a8..00000000000
--- a/lib/Doctrine/ORM/Mapping/Reflection/ReflectionPropertiesGetter.php
+++ /dev/null
@@ -1,135 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\ORM\Mapping\Reflection;
-
-use Doctrine\Persistence\Mapping\ReflectionService;
-use ReflectionClass;
-use ReflectionProperty;
-
-use function array_combine;
-use function array_filter;
-use function array_map;
-use function array_merge;
-use function call_user_func_array;
-
-/**
- * Utility class to retrieve all reflection instance properties of a given class, including
- * private inherited properties and transient properties.
- *
- * @private This API is for internal use only
- */
-final class ReflectionPropertiesGetter
-{
-    /** @var ReflectionProperty[][] indexed by class name and property internal name */
-    private $properties = [];
-
-    /** @var ReflectionService */
-    private $reflectionService;
-
-    public function __construct(ReflectionService $reflectionService)
-    {
-        $this->reflectionService = $reflectionService;
-    }
-
-    /**
-     * @param string $className
-     * @psalm-param class-string $className
-     *
-     * @return ReflectionProperty[] indexed by property internal name
-     */
-    public function getProperties($className): array
-    {
-        if (isset($this->properties[$className])) {
-            return $this->properties[$className];
-        }
-
-        return $this->properties[$className] = call_user_func_array(
-            'array_merge',
-            // first merge because `array_merge` expects >= 1 params
-            array_merge(
-                [[]],
-                array_map(
-                    [$this, 'getClassProperties'],
-                    $this->getHierarchyClasses($className)
-                )
-            )
-        );
-    }
-
-    /**
-     * @psalm-param class-string $className
-     *
-     * @return ReflectionClass[]
-     * @psalm-return list<ReflectionClass<object>>
-     */
-    private function getHierarchyClasses(string $className): array
-    {
-        $classes         = [];
-        $parentClassName = $className;
-
-        while ($parentClassName && $currentClass = $this->reflectionService->getClass($parentClassName)) {
-            $classes[]       = $currentClass;
-            $parentClassName = null;
-
-            $parentClass = $currentClass->getParentClass();
-            if ($parentClass) {
-                $parentClassName = $parentClass->getName();
-            }
-        }
-
-        return $classes;
-    }
-
-    //  phpcs:disable SlevomatCodingStandard.Classes.UnusedPrivateElements.UnusedMethod
-
-    /**
-     * @return ReflectionProperty[]
-     * @psalm-return array<string, ReflectionProperty>
-     */
-    private function getClassProperties(ReflectionClass $reflectionClass): array
-    {
-        //  phpcs:enable SlevomatCodingStandard.Classes.UnusedPrivateElements.UnusedMethod
-        $properties = $reflectionClass->getProperties();
-
-        return array_filter(
-            array_filter(array_map(
-                [$this, 'getAccessibleProperty'],
-                array_combine(
-                    array_map([$this, 'getLogicalName'], $properties),
-                    $properties
-                )
-            )),
-            [$this, 'isInstanceProperty']
-        );
-    }
-
-    private function isInstanceProperty(ReflectionProperty $reflectionProperty): bool
-    {
-        return ! $reflectionProperty->isStatic();
-    }
-
-    private function getAccessibleProperty(ReflectionProperty $property): ?ReflectionProperty
-    {
-        return $this->reflectionService->getAccessibleProperty(
-            $property->getDeclaringClass()->getName(),
-            $property->getName()
-        );
-    }
-
-    private function getLogicalName(ReflectionProperty $property): string
-    {
-        $propertyName = $property->getName();
-
-        if ($property->isPublic()) {
-            return $propertyName;
-        }
-
-        if ($property->isProtected()) {
-            return "\0*\0" . $propertyName;
-        }
-
-        return "\0" . $property->getDeclaringClass()->getName() . "\0" . $propertyName;
-    }
-}
diff --git a/lib/Doctrine/ORM/UnitOfWork.php b/lib/Doctrine/ORM/UnitOfWork.php
index 19d2ab9e67c..b513639c342 100644
--- a/lib/Doctrine/ORM/UnitOfWork.php
+++ b/lib/Doctrine/ORM/UnitOfWork.php
@@ -26,7 +26,6 @@
 use Doctrine\ORM\Internal\HydrationCompleteHandler;
 use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\Mapping\MappingException;
-use Doctrine\ORM\Mapping\Reflection\ReflectionPropertiesGetter;
 use Doctrine\ORM\Persisters\Collection\CollectionPersister;
 use Doctrine\ORM\Persisters\Collection\ManyToManyPersister;
 use Doctrine\ORM\Persisters\Collection\OneToManyPersister;
@@ -35,7 +34,6 @@
 use Doctrine\ORM\Persisters\Entity\JoinedSubclassPersister;
 use Doctrine\ORM\Persisters\Entity\SingleTablePersister;
 use Doctrine\ORM\Utility\IdentifierFlattener;
-use Doctrine\Persistence\Mapping\RuntimeReflectionService;
 use Doctrine\Persistence\NotifyPropertyChanged;
 use Doctrine\Persistence\ObjectManagerAware;
 use Doctrine\Persistence\PropertyChangedListener;
@@ -228,11 +226,6 @@ class UnitOfWork implements PropertyChangedListener
      */
     private array $visitedCollections = [];
 
-    /**
-     * The EntityManager that "owns" this UnitOfWork instance.
-     */
-    private EntityManagerInterface $em;
-
     /**
      * The entity persister instances used to persist entity instances.
      *
@@ -290,20 +283,19 @@ class UnitOfWork implements PropertyChangedListener
      */
     private HydrationCompleteHandler $hydrationCompleteHandler;
 
-    private ReflectionPropertiesGetter $reflectionPropertiesGetter;
-
     /**
      * Initializes a new UnitOfWork instance, bound to the given EntityManager.
+     *
+     * @param EntityManagerInterface $em The EntityManager that "owns" this UnitOfWork instance.
      */
-    public function __construct(EntityManagerInterface $em)
-    {
-        $this->em                         = $em;
-        $this->evm                        = $em->getEventManager();
-        $this->listenersInvoker           = new ListenersInvoker($em);
-        $this->hasCache                   = $em->getConfiguration()->isSecondLevelCacheEnabled();
-        $this->identifierFlattener        = new IdentifierFlattener($this, $em->getMetadataFactory());
-        $this->hydrationCompleteHandler   = new HydrationCompleteHandler($this->listenersInvoker, $em);
-        $this->reflectionPropertiesGetter = new ReflectionPropertiesGetter(new RuntimeReflectionService());
+    public function __construct(
+        private EntityManagerInterface $em
+    ) {
+        $this->evm                      = $em->getEventManager();
+        $this->listenersInvoker         = new ListenersInvoker($em);
+        $this->hasCache                 = $em->getConfiguration()->isSecondLevelCacheEnabled();
+        $this->identifierFlattener      = new IdentifierFlattener($this, $em->getMetadataFactory());
+        $this->hydrationCompleteHandler = new HydrationCompleteHandler($this->listenersInvoker, $em);
     }
 
     /**
@@ -1724,198 +1716,6 @@ private function doRemove(object $entity, array &$visited): void
         }
     }
 
-    /**
-     * Merges the state of the given detached entity into this UnitOfWork.
-     *
-     * @deprecated 2.7 This method is being removed from the ORM and won't have any replacement
-     *
-     * @return object The managed copy of the entity.
-     *
-     * @throws OptimisticLockException If the entity uses optimistic locking through a version
-     *         attribute and the version check against the managed copy fails.
-     */
-    public function merge(object $entity): object
-    {
-        $visited = [];
-
-        return $this->doMerge($entity, $visited);
-    }
-
-    /**
-     * Executes a merge operation on an entity.
-     *
-     * @param string[] $assoc
-     * @psalm-param array<int, object> $visited
-     *
-     * @return object The managed copy of the entity.
-     *
-     * @throws OptimisticLockException If the entity uses optimistic locking through a version
-     *         attribute and the version check against the managed copy fails.
-     * @throws ORMInvalidArgumentException If the entity instance is NEW.
-     * @throws EntityNotFoundException if an assigned identifier is used in the entity, but none is provided.
-     */
-    private function doMerge(
-        object $entity,
-        array &$visited,
-        ?object $prevManagedCopy = null,
-        array $assoc = []
-    ): object {
-        $oid = spl_object_id($entity);
-
-        if (isset($visited[$oid])) {
-            $managedCopy = $visited[$oid];
-
-            if ($prevManagedCopy !== null) {
-                $this->updateAssociationWithMergedEntity($entity, $assoc, $prevManagedCopy, $managedCopy);
-            }
-
-            return $managedCopy;
-        }
-
-        $class = $this->em->getClassMetadata(get_class($entity));
-
-        // First we assume DETACHED, although it can still be NEW but we can avoid
-        // an extra db-roundtrip this way. If it is not MANAGED but has an identity,
-        // we need to fetch it from the db anyway in order to merge.
-        // MANAGED entities are ignored by the merge operation.
-        $managedCopy = $entity;
-
-        if ($this->getEntityState($entity, self::STATE_DETACHED) !== self::STATE_MANAGED) {
-            // Try to look the entity up in the identity map.
-            $id = $class->getIdentifierValues($entity);
-
-            // If there is no ID, it is actually NEW.
-            if (! $id) {
-                $managedCopy = $this->newInstance($class);
-
-                $this->mergeEntityStateIntoManagedCopy($entity, $managedCopy);
-                $this->persistNew($class, $managedCopy);
-            } else {
-                $flatId = $class->containsForeignIdentifier
-                    ? $this->identifierFlattener->flattenIdentifier($class, $id)
-                    : $id;
-
-                $managedCopy = $this->tryGetById($flatId, $class->rootEntityName);
-
-                if ($managedCopy) {
-                    // We have the entity in-memory already, just make sure its not removed.
-                    if ($this->getEntityState($managedCopy) === self::STATE_REMOVED) {
-                        throw ORMInvalidArgumentException::entityIsRemoved($managedCopy, 'merge');
-                    }
-                } else {
-                    // We need to fetch the managed copy in order to merge.
-                    $managedCopy = $this->em->find($class->name, $flatId);
-                }
-
-                if ($managedCopy === null) {
-                    // If the identifier is ASSIGNED, it is NEW, otherwise an error
-                    // since the managed entity was not found.
-                    if (! $class->isIdentifierNatural()) {
-                        throw EntityNotFoundException::fromClassNameAndIdentifier(
-                            $class->getName(),
-                            $this->identifierFlattener->flattenIdentifier($class, $id)
-                        );
-                    }
-
-                    $managedCopy = $this->newInstance($class);
-                    $class->setIdentifierValues($managedCopy, $id);
-
-                    $this->mergeEntityStateIntoManagedCopy($entity, $managedCopy);
-                    $this->persistNew($class, $managedCopy);
-                } else {
-                    $this->ensureVersionMatch($class, $entity, $managedCopy);
-                    $this->mergeEntityStateIntoManagedCopy($entity, $managedCopy);
-                }
-            }
-
-            $visited[$oid] = $managedCopy; // mark visited
-
-            if ($class->isChangeTrackingDeferredExplicit()) {
-                $this->scheduleForDirtyCheck($entity);
-            }
-        }
-
-        if ($prevManagedCopy !== null) {
-            $this->updateAssociationWithMergedEntity($entity, $assoc, $prevManagedCopy, $managedCopy);
-        }
-
-        // Mark the managed copy visited as well
-        $visited[spl_object_id($managedCopy)] = $managedCopy;
-
-        $this->cascadeMerge($entity, $managedCopy, $visited);
-
-        return $managedCopy;
-    }
-
-    /**
-     * @psalm-param ClassMetadata<T> $class
-     * @psalm-param T $entity
-     * @psalm-param T $managedCopy
-     *
-     * @throws OptimisticLockException
-     *
-     * @template T of object
-     */
-    private function ensureVersionMatch(
-        ClassMetadata $class,
-        object $entity,
-        object $managedCopy
-    ): void {
-        if (! ($class->isVersioned && $this->isLoaded($managedCopy) && $this->isLoaded($entity))) {
-            return;
-        }
-
-        $reflField          = $class->reflFields[$class->versionField];
-        $managedCopyVersion = $reflField->getValue($managedCopy);
-        $entityVersion      = $reflField->getValue($entity);
-
-        // Throw exception if versions don't match.
-        // phpcs:ignore SlevomatCodingStandard.Operators.DisallowEqualOperators.DisallowedEqualOperator
-        if ($managedCopyVersion == $entityVersion) {
-            return;
-        }
-
-        throw OptimisticLockException::lockFailedVersionMismatch($entity, $entityVersion, $managedCopyVersion);
-    }
-
-    /**
-     * Tests if an entity is loaded - must either be a loaded proxy or not a proxy
-     */
-    private function isLoaded(object $entity): bool
-    {
-        return ! ($entity instanceof Proxy) || $entity->__isInitialized();
-    }
-
-    /**
-     * Sets/adds associated managed copies into the previous entity's association field
-     *
-     * @param string[] $association
-     */
-    private function updateAssociationWithMergedEntity(
-        object $entity,
-        array $association,
-        object $previousManagedCopy,
-        object $managedCopy
-    ): void {
-        $assocField = $association['fieldName'];
-        $prevClass  = $this->em->getClassMetadata(get_class($previousManagedCopy));
-
-        if ($association['type'] & ClassMetadata::TO_ONE) {
-            $prevClass->reflFields[$assocField]->setValue($previousManagedCopy, $managedCopy);
-
-            return;
-        }
-
-        $value   = $prevClass->reflFields[$assocField]->getValue($previousManagedCopy);
-        $value[] = $managedCopy;
-
-        if ($association['type'] === ClassMetadata::ONE_TO_MANY) {
-            $class = $this->em->getClassMetadata(get_class($entity));
-
-            $class->reflFields[$association['mappedBy']]->setValue($managedCopy, $previousManagedCopy);
-        }
-    }
-
     /**
      * Detaches an entity from the persistence management. It's persistence will
      * no longer be managed by Doctrine.
@@ -2101,44 +1901,6 @@ static function (array $assoc) {
         }
     }
 
-    /**
-     * Cascades a merge operation to associated entities.
-     *
-     * @psalm-param array<int, object> $visited
-     */
-    private function cascadeMerge(object $entity, object $managedCopy, array &$visited): void
-    {
-        $class = $this->em->getClassMetadata(get_class($entity));
-
-        $associationMappings = array_filter(
-            $class->associationMappings,
-            static function (array $assoc) {
-                return $assoc['isCascadeMerge'];
-            }
-        );
-
-        foreach ($associationMappings as $assoc) {
-            $relatedEntities = $class->reflFields[$assoc['fieldName']]->getValue($entity);
-
-            if ($relatedEntities instanceof Collection) {
-                if ($relatedEntities === $class->reflFields[$assoc['fieldName']]->getValue($managedCopy)) {
-                    continue;
-                }
-
-                if ($relatedEntities instanceof PersistentCollection) {
-                    // Unwrap so that foreach() does not initialize
-                    $relatedEntities = $relatedEntities->unwrap();
-                }
-
-                foreach ($relatedEntities as $relatedEntity) {
-                    $this->doMerge($relatedEntity, $visited, $managedCopy, $assoc);
-                }
-            } elseif ($relatedEntities !== null) {
-                $this->doMerge($relatedEntities, $visited, $managedCopy, $assoc);
-            }
-        }
-    }
-
     /**
      * Cascades the save operation to associated entities.
      *
@@ -3194,112 +2956,6 @@ private function assertThatThereAreNoUnintentionallyNonPersistedAssociations():
         }
     }
 
-    /**
-     * @throws ORMException
-     * @throws OptimisticLockException
-     * @throws TransactionRequiredException
-     */
-    private function mergeEntityStateIntoManagedCopy(object $entity, object $managedCopy): void
-    {
-        if (! $this->isLoaded($entity)) {
-            return;
-        }
-
-        if (! $this->isLoaded($managedCopy)) {
-            $managedCopy->__load();
-        }
-
-        $class = $this->em->getClassMetadata(get_class($entity));
-
-        foreach ($this->reflectionPropertiesGetter->getProperties($class->name) as $prop) {
-            $name = $prop->name;
-
-            $prop->setAccessible(true);
-
-            if (! isset($class->associationMappings[$name])) {
-                if (! $class->isIdentifier($name)) {
-                    $prop->setValue($managedCopy, $prop->getValue($entity));
-                }
-            } else {
-                $assoc2 = $class->associationMappings[$name];
-
-                if ($assoc2['type'] & ClassMetadata::TO_ONE) {
-                    $other = $prop->getValue($entity);
-                    if ($other === null) {
-                        $prop->setValue($managedCopy, null);
-                    } else {
-                        if ($other instanceof Proxy && ! $other->__isInitialized()) {
-                            // do not merge fields marked lazy that have not been fetched.
-                            continue;
-                        }
-
-                        if (! $assoc2['isCascadeMerge']) {
-                            if ($this->getEntityState($other) === self::STATE_DETACHED) {
-                                $targetClass = $this->em->getClassMetadata($assoc2['targetEntity']);
-                                $relatedId   = $targetClass->getIdentifierValues($other);
-
-                                if ($targetClass->subClasses) {
-                                    $other = $this->em->find($targetClass->name, $relatedId);
-                                } else {
-                                    $other = $this->em->getProxyFactory()->getProxy(
-                                        $assoc2['targetEntity'],
-                                        $relatedId
-                                    );
-                                    $this->registerManaged($other, $relatedId, []);
-                                }
-                            }
-
-                            $prop->setValue($managedCopy, $other);
-                        }
-                    }
-                } else {
-                    $mergeCol = $prop->getValue($entity);
-
-                    if ($mergeCol instanceof PersistentCollection && ! $mergeCol->isInitialized()) {
-                        // do not merge fields marked lazy that have not been fetched.
-                        // keep the lazy persistent collection of the managed copy.
-                        continue;
-                    }
-
-                    $managedCol = $prop->getValue($managedCopy);
-
-                    if (! $managedCol) {
-                        $managedCol = new PersistentCollection(
-                            $this->em,
-                            $this->em->getClassMetadata($assoc2['targetEntity']),
-                            new ArrayCollection()
-                        );
-                        $managedCol->setOwner($managedCopy, $assoc2);
-                        $prop->setValue($managedCopy, $managedCol);
-                    }
-
-                    if ($assoc2['isCascadeMerge']) {
-                        $managedCol->initialize();
-
-                        // clear and set dirty a managed collection if its not also the same collection to merge from.
-                        if (! $managedCol->isEmpty() && $managedCol !== $mergeCol) {
-                            $managedCol->unwrap()->clear();
-                            $managedCol->setDirty(true);
-
-                            if (
-                                $assoc2['isOwningSide']
-                                && $assoc2['type'] === ClassMetadata::MANY_TO_MANY
-                                && $class->isChangeTrackingNotify()
-                            ) {
-                                $this->scheduleForDirtyCheck($managedCopy);
-                            }
-                        }
-                    }
-                }
-            }
-
-            if ($class->isChangeTrackingNotify()) {
-                // Just treat all properties as changed, there is no other choice.
-                $this->propertyChanged($managedCopy, $name, null, $prop->getValue($managedCopy));
-            }
-        }
-    }
-
     /**
      * This method called by hydrators, and indicates that hydrator totally completed current hydration cycle.
      * Unit of work able to fire deferred events, related to loading events here.
diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index e5f7b802fad..4d275f3b11d 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -1400,11 +1400,6 @@ parameters:
 			count: 1
 			path: lib/Doctrine/ORM/Tools/SchemaTool.php
 
-		-
-			message: "#^Binary operation \"&\" between string and 3 results in an error\\.$#"
-			count: 1
-			path: lib/Doctrine/ORM/UnitOfWork.php
-
 		-
 			message: "#^Call to an undefined method Doctrine\\\\Common\\\\Collections\\\\Collection\\<\\(int\\|string\\), object\\>\\:\\:getMapping\\(\\)\\.$#"
 			count: 2
@@ -1430,11 +1425,6 @@ parameters:
 			count: 1
 			path: lib/Doctrine/ORM/UnitOfWork.php
 
-		-
-			message: "#^Strict comparison using \\=\\=\\= between string and 4 will always evaluate to false\\.$#"
-			count: 1
-			path: lib/Doctrine/ORM/UnitOfWork.php
-
 		-
 			message: "#^Access to an undefined property Doctrine\\\\Persistence\\\\Mapping\\\\ClassMetadata\\:\\:\\$name\\.$#"
 			count: 1
diff --git a/psalm-baseline.xml b/psalm-baseline.xml
index 3b0c2b33c6d..668f827b87a 100644
--- a/psalm-baseline.xml
+++ b/psalm-baseline.xml
@@ -244,14 +244,12 @@
       <code>ProxyFactory</code>
       <code>ProxyFactory</code>
     </DeprecatedClass>
-    <DeprecatedMethod occurrences="4">
+    <DeprecatedMethod occurrences="3">
       <code>getAutoGenerateProxyClasses</code>
       <code>getProxyDir</code>
       <code>getProxyNamespace</code>
-      <code>merge</code>
     </DeprecatedMethod>
-    <DocblockTypeContradiction occurrences="5">
-      <code>is_object($entity)</code>
+    <DocblockTypeContradiction occurrences="4">
       <code>is_object($entity)</code>
       <code>is_object($entity)</code>
       <code>is_object($entity)</code>
@@ -282,8 +280,7 @@
     <MoreSpecificReturnType occurrences="1">
       <code>EntityRepository&lt;T&gt;</code>
     </MoreSpecificReturnType>
-    <ParamNameMismatch occurrences="7">
-      <code>$entity</code>
+    <ParamNameMismatch occurrences="6">
       <code>$entity</code>
       <code>$entity</code>
       <code>$entity</code>
@@ -2800,25 +2797,17 @@
       <code>$collectionToUpdate</code>
       <code>$commitOrder[$i]</code>
     </ArgumentTypeCoercion>
-    <DocblockTypeContradiction occurrences="2">
-      <code>$association['type'] === ClassMetadata::ONE_TO_MANY</code>
-      <code>$association['type'] === ClassMetadata::ONE_TO_MANY</code>
-    </DocblockTypeContradiction>
     <InvalidArgument occurrences="1">
       <code>$em-&gt;getMetadataFactory()</code>
     </InvalidArgument>
     <InvalidNullableReturnType occurrences="1">
       <code>object</code>
     </InvalidNullableReturnType>
-    <InvalidOperand occurrences="1">
-      <code>$association['type']</code>
-    </InvalidOperand>
     <InvalidPropertyAssignmentValue occurrences="2">
       <code>$this-&gt;entityChangeSets</code>
       <code>$this-&gt;entityChangeSets</code>
     </InvalidPropertyAssignmentValue>
-    <MissingClosureReturnType occurrences="5">
-      <code>static function (array $assoc) {</code>
+    <MissingClosureReturnType occurrences="4">
       <code>static function (array $assoc) {</code>
       <code>static function (array $assoc) {</code>
       <code>static function (array $assoc) {</code>
@@ -2845,7 +2834,7 @@
       <code>$assoc['targetEntity']</code>
       <code>$assoc['type']</code>
     </PossiblyNullArrayAccess>
-    <PossiblyNullReference occurrences="33">
+    <PossiblyNullReference occurrences="27">
       <code>buildCachedCollectionPersister</code>
       <code>buildCachedEntityPersister</code>
       <code>getCacheFactory</code>
@@ -2858,12 +2847,6 @@
       <code>getValue</code>
       <code>getValue</code>
       <code>getValue</code>
-      <code>getValue</code>
-      <code>getValue</code>
-      <code>getValue</code>
-      <code>getValue</code>
-      <code>setValue</code>
-      <code>setValue</code>
       <code>setValue</code>
       <code>setValue</code>
       <code>setValue</code>
diff --git a/tests/Doctrine/Tests/ORM/EntityManagerTest.php b/tests/Doctrine/Tests/ORM/EntityManagerTest.php
index 52883c64f2b..4a63c50c951 100644
--- a/tests/Doctrine/Tests/ORM/EntityManagerTest.php
+++ b/tests/Doctrine/Tests/ORM/EntityManagerTest.php
@@ -129,7 +129,6 @@ public static function dataMethodsAffectedByNoObjectArguments(): array
         return [
             ['persist'],
             ['remove'],
-            ['merge'],
             ['refresh'],
             ['detach'],
         ];
@@ -155,7 +154,6 @@ public static function dataAffectedByErrorIfClosedException(): array
             ['flush'],
             ['persist'],
             ['remove'],
-            ['merge'],
             ['refresh'],
         ];
     }
diff --git a/tests/Doctrine/Tests/ORM/Functional/BasicFunctionalTest.php b/tests/Doctrine/Tests/ORM/Functional/BasicFunctionalTest.php
index e71532de57b..d264a635b34 100644
--- a/tests/Doctrine/Tests/ORM/Functional/BasicFunctionalTest.php
+++ b/tests/Doctrine/Tests/ORM/Functional/BasicFunctionalTest.php
@@ -5,7 +5,6 @@
 namespace Doctrine\Tests\ORM\Functional;
 
 use Doctrine\ORM\EntityManagerInterface;
-use Doctrine\ORM\EntityNotFoundException;
 use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\ORMInvalidArgumentException;
 use Doctrine\ORM\PersistentCollection;
@@ -900,97 +899,6 @@ public function testGetPartialReferenceToUpdateObjectWithoutLoadingIt(): void
         self::assertEquals('Benjamin E.', $this->_em->find(get_class($user), $userId)->name);
     }
 
-    public function testMergePersistsNewEntities(): void
-    {
-        $user           = new CmsUser();
-        $user->username = 'beberlei';
-        $user->name     = 'Benjamin E.';
-        $user->status   = 'active';
-
-        $managedUser = $this->_em->merge($user);
-        self::assertEquals('beberlei', $managedUser->username);
-        self::assertEquals('Benjamin E.', $managedUser->name);
-        self::assertEquals('active', $managedUser->status);
-
-        self::assertTrue($user !== $managedUser);
-        self::assertTrue($this->_em->contains($managedUser));
-
-        $this->_em->flush();
-        $userId = $managedUser->id;
-        $this->_em->clear();
-
-        $user2 = $this->_em->find(get_class($managedUser), $userId);
-        self::assertInstanceOf(CmsUser::class, $user2);
-    }
-
-    public function testMergeNonPersistedProperties(): void
-    {
-        $user                             = new CmsUser();
-        $user->username                   = 'beberlei';
-        $user->name                       = 'Benjamin E.';
-        $user->status                     = 'active';
-        $user->nonPersistedProperty       = 'test';
-        $user->nonPersistedPropertyObject = new CmsPhonenumber();
-
-        $managedUser = $this->_em->merge($user);
-        self::assertEquals('test', $managedUser->nonPersistedProperty);
-        self::assertSame($user->nonPersistedProperty, $managedUser->nonPersistedProperty);
-        self::assertSame($user->nonPersistedPropertyObject, $managedUser->nonPersistedPropertyObject);
-
-        self::assertTrue($user !== $managedUser);
-        self::assertTrue($this->_em->contains($managedUser));
-
-        $this->_em->flush();
-        $userId = $managedUser->id;
-        $this->_em->clear();
-
-        $user2 = $this->_em->find(get_class($managedUser), $userId);
-        self::assertNull($user2->nonPersistedProperty);
-        self::assertNull($user2->nonPersistedPropertyObject);
-        self::assertEquals('active', $user2->status);
-    }
-
-    public function testMergeThrowsExceptionIfEntityWithGeneratedIdentifierDoesNotExist(): void
-    {
-        $user           = new CmsUser();
-        $user->username = 'beberlei';
-        $user->name     = 'Benjamin E.';
-        $user->status   = 'active';
-        $user->id       = 42;
-
-        $this->expectException(EntityNotFoundException::class);
-        $this->_em->merge($user);
-    }
-
-    /**
-     * @group DDC-634
-     */
-    public function testOneToOneMergeSetNull(): void
-    {
-        $user           = new CmsUser();
-        $user->username = 'beberlei';
-        $user->name     = 'Benjamin E.';
-        $user->status   = 'active';
-
-        $ph              = new CmsPhonenumber();
-        $ph->phonenumber = '12345';
-        $user->addPhonenumber($ph);
-
-        $this->_em->persist($user);
-        $this->_em->persist($ph);
-        $this->_em->flush();
-
-        $this->_em->clear();
-
-        $ph->user  = null;
-        $managedPh = $this->_em->merge($ph);
-
-        $this->_em->flush();
-        $this->_em->clear();
-
-        self::assertNull($this->_em->find(get_class($ph), $ph->phonenumber)->getUser());
-    }
-
     /**
      * @group DDC-952
      */
diff --git a/tests/Doctrine/Tests/ORM/Functional/DetachedEntityTest.php b/tests/Doctrine/Tests/ORM/Functional/DetachedEntityTest.php
index 463eef39003..37461ed8f1c 100644
--- a/tests/Doctrine/Tests/ORM/Functional/DetachedEntityTest.php
+++ b/tests/Doctrine/Tests/ORM/Functional/DetachedEntityTest.php
@@ -5,19 +5,10 @@
 namespace Doctrine\Tests\ORM\Functional;
 
 use Doctrine\DBAL\Exception\UniqueConstraintViolationException;
-use Doctrine\ORM\OptimisticLockException;
-use Doctrine\ORM\Proxy\Proxy;
-use Doctrine\Tests\Models\CMS\CmsAddress;
-use Doctrine\Tests\Models\CMS\CmsArticle;
 use Doctrine\Tests\Models\CMS\CmsPhonenumber;
 use Doctrine\Tests\Models\CMS\CmsUser;
 use Doctrine\Tests\OrmFunctionalTestCase;
 
-use function count;
-use function get_class;
-use function serialize;
-use function unserialize;
-
 /**
  * Description of DetachedEntityTest
  */
@@ -29,89 +20,6 @@ protected function setUp(): void
         parent::setUp();
     }
 
-    public function testSimpleDetachMerge(): void
-    {
-        $user           = new CmsUser();
-        $user->name     = 'Roman';
-        $user->username = 'romanb';
-        $user->status   = 'dev';
-        $this->_em->persist($user);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        // $user is now detached
-        self::assertFalse($this->_em->contains($user));
-
-        $user->name = 'Roman B.';
-
-        $user2 = $this->_em->merge($user);
-
-        self::assertFalse($user === $user2);
-        self::assertTrue($this->_em->contains($user2));
-        self::assertEquals('Roman B.', $user2->name);
-    }
-
-    public function testSerializeUnserializeModifyMerge(): void
-    {
-        $user           = new CmsUser();
-        $user->name     = 'Guilherme';
-        $user->username = 'gblanco';
-        $user->status   = 'developer';
-
-        $ph1              = new CmsPhonenumber();
-        $ph1->phonenumber = '1234';
-        $user->addPhonenumber($ph1);
-
-        $this->_em->persist($user);
-        $this->_em->flush();
-
-        self::assertTrue($this->_em->contains($user));
-        self::assertTrue($user->phonenumbers->isInitialized());
-
-        $serialized = serialize($user);
-
-        $this->_em->clear();
-
-        self::assertFalse($this->_em->contains($user));
-
-        unset($user);
-
-        $user = unserialize($serialized);
-
-        self::assertEquals(1, count($user->getPhonenumbers()), 'Pre-Condition: 1 Phonenumber');
-
-        $ph2 = new CmsPhonenumber();
-
-        $ph2->phonenumber = '56789';
-        $user->addPhonenumber($ph2);
-
-        $oldPhonenumbers = $user->getPhonenumbers();
-
-        self::assertEquals(2, count($oldPhonenumbers), 'Pre-Condition: 2 Phonenumbers');
-        self::assertFalse($this->_em->contains($user));
-
-        $this->_em->persist($ph2);
-
-        // Merge back in
-        $user = $this->_em->merge($user); // merge cascaded to phonenumbers
-        self::assertInstanceOf(CmsUser::class, $user->phonenumbers[0]->user);
-        self::assertInstanceOf(CmsUser::class, $user->phonenumbers[1]->user);
-        $im = $this->_em->getUnitOfWork()->getIdentityMap();
-        $this->_em->flush();
-
-        self::assertTrue($this->_em->contains($user), 'Failed to assert that merged user is contained inside EntityManager persistence context.');
-        $phonenumbers = $user->getPhonenumbers();
-        self::assertNotSame($oldPhonenumbers, $phonenumbers, 'Merge should replace the Detached Collection with a new PersistentCollection.');
-        self::assertEquals(2, count($phonenumbers), 'Failed to assert that two phonenumbers are contained in the merged users phonenumber collection.');
-
-        self::assertInstanceOf(CmsPhonenumber::class, $phonenumbers[1]);
-        self::assertTrue($this->_em->contains($phonenumbers[1]), 'Failed to assert that second phonenumber in collection is contained inside EntityManager persistence context.');
-
-        self::assertInstanceOf(CmsPhonenumber::class, $phonenumbers[0]);
-        self::assertTrue($this->_em->getUnitOfWork()->isInIdentityMap($phonenumbers[0]));
-        self::assertTrue($this->_em->contains($phonenumbers[0]), 'Failed to assert that first phonenumber in collection is contained inside EntityManager persistence context.');
-    }
-
     /**
      * @group DDC-203
      */
@@ -131,38 +39,6 @@ public function testDetachedEntityThrowsExceptionOnFlush(): void
         $this->_em->flush();
     }
 
-    public function testUninitializedLazyAssociationsAreIgnoredOnMerge(): void
-    {
-        $user           = new CmsUser();
-        $user->name     = 'Guilherme';
-        $user->username = 'gblanco';
-        $user->status   = 'developer';
-
-        $address          = new CmsAddress();
-        $address->city    = 'Berlin';
-        $address->country = 'Germany';
-        $address->street  = 'Sesamestreet';
-        $address->zip     = 12345;
-        $address->setUser($user);
-        $this->_em->persist($address);
-        $this->_em->persist($user);
-
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $address2 = $this->_em->find(get_class($address), $address->id);
-        self::assertInstanceOf(Proxy::class, $address2->user);
-        self::assertFalse($address2->user->__isInitialized__);
-        $detachedAddress2 = unserialize(serialize($address2));
-        self::assertInstanceOf(Proxy::class, $detachedAddress2->user);
-        self::assertFalse($detachedAddress2->user->__isInitialized__);
-
-        $managedAddress2 = $this->_em->merge($detachedAddress2);
-        self::assertInstanceOf(Proxy::class, $managedAddress2->user);
-        self::assertFalse($managedAddress2->user === $detachedAddress2->user);
-        self::assertFalse($managedAddress2->user->__isInitialized__);
-    }
-
     /**
      * @group DDC-822
      */
@@ -206,27 +82,4 @@ public function testDetachManagedUnpersistedEntity(): void
         self::assertFalse($this->_em->contains($user));
         self::assertFalse($this->_em->getUnitOfWork()->isInIdentityMap($user));
     }
-
-    /**
-     * @group DDC-1340
-     */
-    public function testMergeArticleWrongVersion(): void
-    {
-        $article        = new CmsArticle();
-        $article->topic = 'test';
-        $article->text  = 'test';
-
-        $this->_em->persist($article);
-        $this->_em->flush();
-
-        $this->_em->detach($article);
-
-        $sql = 'UPDATE cms_articles SET version = version + 1 WHERE id = ' . $article->id;
-        $this->_em->getConnection()->executeStatement($sql);
-
-        $this->expectException(OptimisticLockException::class);
-        $this->expectExceptionMessage('The optimistic lock failed, version 1 was expected, but is actually 2');
-
-        $this->_em->merge($article);
-    }
 }
diff --git a/tests/Doctrine/Tests/ORM/Functional/EntityRepositoryTest.php b/tests/Doctrine/Tests/ORM/Functional/EntityRepositoryTest.php
index 3a125acc4fa..a4237dfdb1c 100644
--- a/tests/Doctrine/Tests/ORM/Functional/EntityRepositoryTest.php
+++ b/tests/Doctrine/Tests/ORM/Functional/EntityRepositoryTest.php
@@ -939,7 +939,7 @@ public function testMatchingCriteriaEndsWithComparison(): void
     public function testMatchingCriteriaNullAssocComparison(): void
     {
         $fixtures       = $this->loadFixtureUserEmail();
-        $user           = $this->_em->merge($fixtures[0]);
+        $user           = $this->_em->find(CmsUser::class, $fixtures[0]->id);
         $repository     = $this->_em->getRepository(CmsUser::class);
         $criteriaIsNull = Criteria::create()->where(Criteria::expr()->isNull('email'));
         $criteriaEqNull = Criteria::create()->where(Criteria::expr()->eq('email', null));
diff --git a/tests/Doctrine/Tests/ORM/Functional/MergeCompositeToOneKeyTest.php b/tests/Doctrine/Tests/ORM/Functional/MergeCompositeToOneKeyTest.php
deleted file mode 100644
index e4672d9ffe1..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/MergeCompositeToOneKeyTest.php
+++ /dev/null
@@ -1,48 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional;
-
-use Doctrine\Tests\Models\MixedToOneIdentity\CompositeToOneKeyState;
-use Doctrine\Tests\Models\MixedToOneIdentity\Country;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-use function assert;
-
-class MergeCompositeToOneKeyTest extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        parent::setUp();
-
-        $this->_schemaTool->createSchema(
-            [
-                $this->_em->getClassMetadata(Country::class),
-                $this->_em->getClassMetadata(CompositeToOneKeyState::class),
-            ]
-        );
-    }
-
-    /**
-     * @group DDC-3378
-     * @group 1176
-     */
-    public function testMergingOfEntityWithCompositeIdentifierContainingToOneAssociation(): void
-    {
-        $country          = new Country();
-        $country->country = 'US';
-
-        $state          = new CompositeToOneKeyState();
-        $state->state   = 'CA';
-        $state->country = $country;
-
-        $merged = $this->_em->merge($state);
-        assert($merged instanceof CompositeToOneKeyState);
-
-        self::assertInstanceOf(CompositeToOneKeyState::class, $state);
-        self::assertNotSame($state, $merged);
-        self::assertInstanceOf(Country::class, $merged->country);
-        self::assertNotSame($country, $merged->country);
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/MergeProxiesTest.php b/tests/Doctrine/Tests/ORM/Functional/MergeProxiesTest.php
deleted file mode 100644
index 5a7bc9bc805..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/MergeProxiesTest.php
+++ /dev/null
@@ -1,274 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional;
-
-use DateTime;
-use Doctrine\DBAL\DriverManager;
-use Doctrine\ORM\Configuration;
-use Doctrine\ORM\EntityManager;
-use Doctrine\ORM\EntityManagerInterface;
-use Doctrine\ORM\ORMSetup;
-use Doctrine\ORM\Proxy\Proxy;
-use Doctrine\ORM\Tools\SchemaTool;
-use Doctrine\Tests\DbalExtensions\Connection;
-use Doctrine\Tests\DbalExtensions\QueryLog;
-use Doctrine\Tests\Models\Generic\DateTimeModel;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-use function assert;
-use function realpath;
-use function serialize;
-use function unserialize;
-
-class MergeProxiesTest extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        $this->useModelSet('generic');
-
-        parent::setUp();
-    }
-
-    /**
-     * @group DDC-1392
-     * @group DDC-1734
-     * @group DDC-3368
-     * @group #1172
-     */
-    public function testMergeDetachedUnInitializedProxy(): void
-    {
-        $detachedUninitialized = $this->_em->getReference(DateTimeModel::class, 123);
-
-        $this->_em->clear();
-
-        $managed = $this->_em->getReference(DateTimeModel::class, 123);
-
-        self::assertSame($managed, $this->_em->merge($detachedUninitialized));
-
-        self::assertFalse($managed->__isInitialized());
-        self::assertFalse($detachedUninitialized->__isInitialized());
-    }
-
-    /**
-     * @group DDC-1392
-     * @group DDC-1734
-     * @group DDC-3368
-     * @group #1172
-     */
-    public function testMergeUnserializedUnInitializedProxy(): void
-    {
-        $detachedUninitialized = $this->_em->getReference(DateTimeModel::class, 123);
-
-        $this->_em->clear();
-
-        $managed = $this->_em->getReference(DateTimeModel::class, 123);
-
-        self::assertSame(
-            $managed,
-            $this->_em->merge(unserialize(serialize($this->_em->merge($detachedUninitialized))))
-        );
-
-        self::assertFalse($managed->__isInitialized());
-        self::assertFalse($detachedUninitialized->__isInitialized());
-    }
-
-    /**
-     * @group DDC-1392
-     * @group DDC-1734
-     * @group DDC-3368
-     * @group #1172
-     */
-    public function testMergeManagedProxy(): void
-    {
-        $managed = $this->_em->getReference(DateTimeModel::class, 123);
-
-        self::assertSame($managed, $this->_em->merge($managed));
-
-        self::assertFalse($managed->__isInitialized());
-    }
-
-    /**
-     * @group DDC-1392
-     * @group DDC-1734
-     * @group DDC-3368
-     * @group #1172
-     *
-     * Bug discovered while working on DDC-2704 - merging towards un-initialized proxies does not initialize them,
-     * causing merged data to be lost when they are actually initialized
-     */
-    public function testMergeWithExistingUninitializedManagedProxy(): void
-    {
-        $date = new DateTimeModel();
-
-        $this->_em->persist($date);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $managed = $this->_em->getReference(DateTimeModel::class, $date->id);
-
-        self::assertInstanceOf(Proxy::class, $managed);
-        self::assertFalse($managed->__isInitialized());
-
-        $date->date = $dateTime = new DateTime();
-
-        self::assertSame($managed, $this->_em->merge($date));
-        self::assertTrue($managed->__isInitialized());
-        self::assertSame($dateTime, $managed->date, 'Data was merged into the proxy after initialization');
-    }
-
-    /**
-     * @group DDC-1392
-     * @group DDC-1734
-     * @group DDC-3368
-     * @group #1172
-     */
-    public function testMergingProxyFromDifferentEntityManagerWithExistingManagedInstanceDoesNotReplaceInitializer(): void
-    {
-        $em1 = $this->createEntityManager();
-        $em2 = $this->createEntityManager();
-
-        $file1 = new DateTimeModel();
-        $file2 = new DateTimeModel();
-
-        $em1->persist($file1);
-        $em2->persist($file2);
-        $em1->flush();
-        $em2->flush();
-        $em1->clear();
-        $em2->clear();
-
-        $logger1 = $this->getResetQueryLogFromEntityManager($em1);
-        $logger2 = $this->getResetQueryLogFromEntityManager($em2);
-
-        $proxy1  = $em1->getReference(DateTimeModel::class, $file1->id);
-        $proxy2  = $em2->getReference(DateTimeModel::class, $file1->id);
-        $merged2 = $em2->merge($proxy1);
-
-        self::assertNotSame($proxy1, $merged2);
-        self::assertSame($proxy2, $merged2);
-
-        self::assertFalse($proxy1->__isInitialized());
-        self::assertFalse($proxy2->__isInitialized());
-
-        $proxy1->__load();
-
-        self::assertCount(
-            1,
-            $logger1->queries,
-            'Loading the first proxy was done through the first entity manager'
-        );
-        self::assertCount(
-            0,
-            $logger2->queries,
-            'No queries were executed on the second entity manager, as it is unrelated with the first proxy'
-        );
-
-        $proxy2->__load();
-
-        self::assertCount(
-            1,
-            $logger1->queries,
-            'Loading the second proxy does not affect the first entity manager'
-        );
-        self::assertCount(
-            1,
-            $logger2->queries,
-            'Loading of the second proxy instance was done through the second entity manager'
-        );
-    }
-
-    /**
-     * @group DDC-1392
-     * @group DDC-1734
-     * @group DDC-3368
-     * @group #1172
-     */
-    public function testMergingUnInitializedProxyDoesNotInitializeIt(): void
-    {
-        $em1 = $this->createEntityManager();
-        $em2 = $this->createEntityManager();
-
-        $file1 = new DateTimeModel();
-        $file2 = new DateTimeModel();
-
-        $em1->persist($file1);
-        $em2->persist($file2);
-        $em1->flush();
-        $em2->flush();
-        $em1->clear();
-        $em2->clear();
-
-        $logger1 = $this->getResetQueryLogFromEntityManager($em1);
-        $logger2 = $this->getResetQueryLogFromEntityManager($em2);
-
-        $unManagedProxy = $em1->getReference(DateTimeModel::class, $file1->id);
-        $mergedInstance = $em2->merge($unManagedProxy);
-
-        self::assertNotInstanceOf(Proxy::class, $mergedInstance);
-        self::assertNotSame($unManagedProxy, $mergedInstance);
-        self::assertFalse($unManagedProxy->__isInitialized());
-
-        self::assertCount(
-            0,
-            $logger1->queries,
-            'Loading the merged instance affected only the first entity manager'
-        );
-        self::assertCount(
-            1,
-            $logger2->queries,
-            'Loading the merged instance was done via the second entity manager'
-        );
-
-        $unManagedProxy->__load();
-
-        self::assertCount(
-            1,
-            $logger1->queries,
-            'Loading the first proxy was done through the first entity manager'
-        );
-        self::assertCount(
-            1,
-            $logger2->queries,
-            'No queries were executed on the second entity manager, as it is unrelated with the first proxy'
-        );
-    }
-
-    private function createEntityManager(): EntityManagerInterface
-    {
-        $config = new Configuration();
-
-        $config->setProxyDir(realpath(__DIR__ . '/../../Proxies'));
-        $config->setProxyNamespace('Doctrine\Tests\Proxies');
-        $config->setMetadataDriverImpl(ORMSetup::createDefaultAnnotationDriver(
-            [realpath(__DIR__ . '/../../Models/Cache')]
-        ));
-
-        // always runs on sqlite to prevent multi-connection race-conditions with the test suite
-        // multi-connection is not relevant for the purpose of checking locking here, but merely
-        // to stub out DB-level access and intercept it
-        $connection = DriverManager::getConnection(
-            [
-                'driver' => 'pdo_sqlite',
-                'memory' => true,
-                'wrapperClass' => Connection::class,
-            ],
-            $config
-        );
-
-        $entityManager = EntityManager::create($connection, $config);
-
-        (new SchemaTool($entityManager))->createSchema([$entityManager->getClassMetadata(DateTimeModel::class)]);
-
-        return $entityManager;
-    }
-
-    private function getResetQueryLogFromEntityManager(EntityManagerInterface $entityManager): QueryLog
-    {
-        $connection = $entityManager->getConnection();
-        assert($connection instanceof Connection);
-
-        return $connection->queryLog->reset()->enable();
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/MergeSharedEntitiesTest.php b/tests/Doctrine/Tests/ORM/Functional/MergeSharedEntitiesTest.php
deleted file mode 100644
index e5b5705c12e..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/MergeSharedEntitiesTest.php
+++ /dev/null
@@ -1,170 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional;
-
-use Doctrine\ORM\Mapping\Column;
-use Doctrine\ORM\Mapping\Entity;
-use Doctrine\ORM\Mapping\GeneratedValue;
-use Doctrine\ORM\Mapping\Id;
-use Doctrine\ORM\Mapping\ManyToOne;
-use Doctrine\ORM\Mapping\MappedSuperclass;
-use Doctrine\ORM\Tools\ToolsException;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-use function serialize;
-use function unserialize;
-
-class MergeSharedEntitiesTest extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        parent::setUp();
-
-        try {
-            $this->_schemaTool->createSchema(
-                [
-                    $this->_em->getClassMetadata(MSEFile::class),
-                    $this->_em->getClassMetadata(MSEPicture::class),
-                ]
-            );
-        } catch (ToolsException $ignored) {
-        }
-    }
-
-    public function testMergeSharedNewEntities(): void
-    {
-        $file    = new MSEFile();
-        $picture = new MSEPicture();
-
-        $picture->file      = $file;
-        $picture->otherFile = $file;
-
-        $picture = $this->_em->merge($picture);
-
-        self::assertEquals($picture->file, $picture->otherFile, 'Identical entities must remain identical');
-    }
-
-    public function testMergeSharedManagedEntities(): void
-    {
-        $file    = new MSEFile();
-        $picture = new MSEPicture();
-
-        $picture->file      = $file;
-        $picture->otherFile = $file;
-
-        $this->_em->persist($file);
-        $this->_em->persist($picture);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $picture = $this->_em->merge($picture);
-
-        self::assertEquals($picture->file, $picture->otherFile, 'Identical entities must remain identical');
-    }
-
-    public function testMergeSharedDetachedSerializedEntities(): void
-    {
-        $file    = new MSEFile();
-        $picture = new MSEPicture();
-
-        $picture->file      = $file;
-        $picture->otherFile = $file;
-
-        $serializedPicture = serialize($picture);
-
-        $this->_em->persist($file);
-        $this->_em->persist($picture);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $picture = $this->_em->merge(unserialize($serializedPicture));
-
-        self::assertEquals($picture->file, $picture->otherFile, 'Identical entities must remain identical');
-    }
-
-    /**
-     * @group DDC-2704
-     */
-    public function testMergeInheritedTransientPrivateProperties(): void
-    {
-        $admin1 = new MSEAdmin();
-        $admin2 = new MSEAdmin();
-
-        $admin1->id = 123;
-        $admin2->id = 123;
-
-        $this->_em->persist($admin1);
-
-        $admin2->setSession('zeh current session data');
-
-        self::assertSame($admin1, $this->_em->merge($admin2));
-        self::assertSame('zeh current session data', $admin1->getSession());
-    }
-}
-
-/** @Entity */
-class MSEPicture
-{
-    /**
-     * @var int
-     * @Column(type="integer")
-     * @Id
-     * @GeneratedValue
-     */
-    public $id;
-
-    /**
-     * @var MSEFile
-     * @ManyToOne(targetEntity="MSEFile", cascade={"merge"})
-     */
-    public $file;
-
-    /**
-     * @var MSEFile
-     * @ManyToOne(targetEntity="MSEFile", cascade={"merge"})
-     */
-    public $otherFile;
-}
-
-/** @Entity */
-class MSEFile
-{
-    /**
-     * @var int
-     * @Column(type="integer")
-     * @Id
-     * @GeneratedValue(strategy="AUTO")
-     */
-    public $id;
-}
-
-/** @MappedSuperclass */
-abstract class MSEUser
-{
-    /** @var string */
-    private $session; // intentionally transient property
-
-    public function getSession(): string
-    {
-        return $this->session;
-    }
-
-    public function setSession(string $session): void
-    {
-        $this->session = $session;
-    }
-}
-
-/** @Entity */
-class MSEAdmin extends MSEUser
-{
-    /**
-     * @var int
-     * @Column(type="integer")
-     * @Id
-     * @GeneratedValue(strategy="NONE")
-     */
-    public $id;
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/MergeVersionedManyToOneTest.php b/tests/Doctrine/Tests/ORM/Functional/MergeVersionedManyToOneTest.php
deleted file mode 100644
index ae1ea0786b9..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/MergeVersionedManyToOneTest.php
+++ /dev/null
@@ -1,46 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional;
-
-use Doctrine\Tests\Models\VersionedManyToOne\Article;
-use Doctrine\Tests\Models\VersionedManyToOne\Category;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-/**
- * @group MergeVersionedOneToMany
- */
-class MergeVersionedManyToOneTest extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        $this->useModelSet('versioned_many_to_one');
-
-        parent::setUp();
-    }
-
-    /**
-     * This test case asserts that a detached and unmodified entity could be merge without firing
-     * OptimisticLockException.
-     */
-    public function testSetVersionOnCreate(): void
-    {
-        $category = new Category();
-        $article  = new Article();
-
-        $article->name     = 'Article';
-        $article->category = $category;
-
-        $this->_em->persist($article);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $articleMerged = $this->_em->merge($article);
-
-        $articleMerged->name = 'Article Merged';
-
-        $this->_em->flush();
-        self::assertEquals(2, $articleMerged->version);
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC117Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC117Test.php
index 9a91fe7dd94..883e8108eab 100644
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC117Test.php
+++ b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC117Test.php
@@ -434,22 +434,6 @@ private function loadEditorFixture(): DDC117Editor
         return $this->_em->find(get_class($editor), $editor->id);
     }
 
-    /**
-     * @group DDC-1519
-     */
-    public function testMergeForeignKeyIdentifierEntity(): void
-    {
-        $idCriteria = ['source' => $this->article1->id(), 'target' => $this->article2->id()];
-
-        $refRep = $this->_em->find(DDC117Reference::class, $idCriteria);
-
-        $this->_em->clear();
-        $refRep = $this->_em->merge($refRep);
-
-        self::assertEquals($this->article1->id(), $refRep->source()->id());
-        self::assertEquals($this->article2->id(), $refRep->target()->id());
-    }
-
     /**
      * @group DDC-1652
      */
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1276Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1276Test.php
deleted file mode 100644
index 600b49ca5f3..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1276Test.php
+++ /dev/null
@@ -1,53 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\Tests\Models\CMS\CmsGroup;
-use Doctrine\Tests\Models\CMS\CmsUser;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-use function count;
-
-/**
- * @group DDC-1276
- */
-class DDC1276Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        $this->useModelSet('cms');
-        parent::setUp();
-    }
-
-    public function testIssue(): void
-    {
-        $user           = new CmsUser();
-        $user->name     = 'Benjamin';
-        $user->username = 'beberlei';
-        $user->status   = 'active';
-        $this->_em->persist($user);
-
-        for ($i = 0; $i < 2; $i++) {
-            $group          = new CmsGroup();
-            $group->name    = 'group' . $i;
-            $user->groups[] = $group;
-            $this->_em->persist($group);
-        }
-
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $user   = $this->_em->find(CmsUser::class, $user->id);
-        $cloned = clone $user;
-
-        self::assertSame($user->groups, $cloned->groups);
-        self::assertEquals(2, count($user->groups));
-        $this->_em->merge($cloned);
-
-        self::assertEquals(2, count($user->groups));
-
-        $this->_em->flush();
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1383Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1383Test.php
deleted file mode 100644
index 828d493d6d9..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1383Test.php
+++ /dev/null
@@ -1,120 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\ORM\Mapping\Column;
-use Doctrine\ORM\Mapping\DiscriminatorColumn;
-use Doctrine\ORM\Mapping\DiscriminatorMap;
-use Doctrine\ORM\Mapping\Entity;
-use Doctrine\ORM\Mapping\GeneratedValue;
-use Doctrine\ORM\Mapping\Id;
-use Doctrine\ORM\Mapping\InheritanceType;
-use Doctrine\ORM\Mapping\ManyToOne;
-use Doctrine\Tests\OrmFunctionalTestCase;
-use Exception;
-
-use function get_debug_type;
-
-/**
- * @group DDC-1383
- */
-class DDC1383Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        parent::setUp();
-
-        try {
-            $this->_schemaTool->createSchema(
-                [
-                    $this->_em->getClassMetadata(DDC1383AbstractEntity::class),
-                    $this->_em->getClassMetadata(DDC1383Entity::class),
-                ]
-            );
-        } catch (Exception $ignored) {
-        }
-    }
-
-    public function testFailingCase(): void
-    {
-        $parent = new DDC1383Entity();
-        $child  = new DDC1383Entity();
-
-        $child->setReference($parent);
-
-        $this->_em->persist($parent);
-        $this->_em->persist($child);
-
-        $id = $child->getId();
-
-        $this->_em->flush();
-        $this->_em->clear();
-
-        // Try merging the parent entity
-        $child  = $this->_em->merge($child);
-        $parent = $child->getReference();
-
-        // Parent is not instance of the abstract class
-        self::assertTrue(
-            $parent instanceof DDC1383AbstractEntity,
-            'Entity class is ' . get_debug_type($parent) . ', "DDC1383AbstractEntity" was expected'
-        );
-
-        // Parent is NOT instance of entity
-        self::assertTrue(
-            $parent instanceof DDC1383Entity,
-            'Entity class is ' . get_debug_type($parent) . ', "DDC1383Entity" was expected'
-        );
-    }
-}
-
-/**
- * @Entity
- * @InheritanceType("JOINED")
- * @DiscriminatorColumn(name="discr", type="integer")
- * @DiscriminatorMap({1 = "DDC1383Entity"})
- */
-abstract class DDC1383AbstractEntity
-{
-    /**
-     * @var int
-     * @Id
-     * @Column(type="integer")
-     * @GeneratedValue
-     */
-    protected $id;
-
-    public function getId(): ?int
-    {
-        return $this->id;
-    }
-
-    public function setId(int $id): void
-    {
-        $this->id = $id;
-    }
-}
-
-/**
- * @Entity
- */
-class DDC1383Entity extends DDC1383AbstractEntity
-{
-    /**
-     * @var DDC1383AbstractEntity
-     * @ManyToOne(targetEntity="DDC1383AbstractEntity")
-     */
-    protected $reference;
-
-    public function getReference(): DDC1383AbstractEntity
-    {
-        return $this->reference;
-    }
-
-    public function setReference(DDC1383AbstractEntity $reference): void
-    {
-        $this->reference = $reference;
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1392Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1392Test.php
deleted file mode 100644
index 05744bc93ac..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1392Test.php
+++ /dev/null
@@ -1,130 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\ORM\Mapping\Column;
-use Doctrine\ORM\Mapping\Entity;
-use Doctrine\ORM\Mapping\GeneratedValue;
-use Doctrine\ORM\Mapping\Id;
-use Doctrine\ORM\Mapping\JoinColumn;
-use Doctrine\ORM\Mapping\ManyToOne;
-use Doctrine\ORM\UnitOfWork;
-use Doctrine\Tests\OrmFunctionalTestCase;
-use Exception;
-
-/**
- * @group DDC-1392
- */
-class DDC1392Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        parent::setUp();
-
-        try {
-            $this->_schemaTool->createSchema(
-                [
-                    $this->_em->getClassMetadata(DDC1392File::class),
-                    $this->_em->getClassMetadata(DDC1392Picture::class),
-                ]
-            );
-        } catch (Exception $ignored) {
-        }
-    }
-
-    public function testFailingCase(): void
-    {
-        $file = new DDC1392File();
-
-        $picture = new DDC1392Picture();
-        $picture->setFile($file);
-
-        $em = $this->_em;
-        $em->persist($picture);
-        $em->flush();
-        $em->clear();
-
-        $fileId    = $file->getFileId();
-        $pictureId = $picture->getPictureId();
-
-        self::assertTrue($fileId > 0);
-
-        $picture = $em->find(DDC1392Picture::class, $pictureId);
-        self::assertEquals(UnitOfWork::STATE_MANAGED, $em->getUnitOfWork()->getEntityState($picture->getFile()), 'Lazy Proxy should be marked MANAGED.');
-
-        $file = $picture->getFile();
-
-        // With this activated there will be no problem
-        //$file->__load();
-
-        $picture->setFile(null);
-
-        $em->clear();
-
-        $em->merge($file);
-
-        $em->flush();
-
-        $q      = $this->_em->createQuery('SELECT COUNT(e) FROM ' . __NAMESPACE__ . '\DDC1392File e');
-        $result = $q->getSingleScalarResult();
-
-        self::assertEquals(1, $result);
-    }
-}
-
-/**
- * @Entity
- */
-class DDC1392Picture
-{
-    /**
-     * @var int
-     * @Column(name="picture_id", type="integer")
-     * @Id
-     * @GeneratedValue
-     */
-    private $pictureId;
-
-    /**
-     * @var DDC1392File
-     * @ManyToOne(targetEntity="DDC1392File", cascade={"persist", "remove"})
-     * @JoinColumn(name="file_id", referencedColumnName="file_id")
-     */
-    private $file;
-
-    public function getPictureId(): int
-    {
-        return $this->pictureId;
-    }
-
-    public function setFile(?DDC1392File $value = null): void
-    {
-        $this->file = $value;
-    }
-
-    public function getFile(): ?DDC1392File
-    {
-        return $this->file;
-    }
-}
-
-/**
- * @Entity
- */
-class DDC1392File
-{
-    /**
-     * @var int
-     * @Column(name="file_id", type="integer")
-     * @Id
-     * @GeneratedValue(strategy="AUTO")
-     */
-    public $fileId;
-
-    public function getFileId(): int
-    {
-        return $this->fileId;
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1509Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1509Test.php
deleted file mode 100644
index 10ba0c85bae..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1509Test.php
+++ /dev/null
@@ -1,145 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\ORM\EntityManager;
-use Doctrine\ORM\Mapping\Column;
-use Doctrine\ORM\Mapping\DiscriminatorColumn;
-use Doctrine\ORM\Mapping\DiscriminatorMap;
-use Doctrine\ORM\Mapping\Entity;
-use Doctrine\ORM\Mapping\GeneratedValue;
-use Doctrine\ORM\Mapping\Id;
-use Doctrine\ORM\Mapping\InheritanceType;
-use Doctrine\ORM\Mapping\ManyToOne;
-use Doctrine\Tests\OrmFunctionalTestCase;
-use Exception;
-
-use function assert;
-
-/**
- * @group DDC-1509
- */
-class DDC1509Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        parent::setUp();
-
-        try {
-            $this->_schemaTool->createSchema(
-                [
-                    $this->_em->getClassMetadata(DDC1509AbstractFile::class),
-                    $this->_em->getClassMetadata(DDC1509File::class),
-                    $this->_em->getClassMetadata(DDC1509Picture::class),
-                ]
-            );
-        } catch (Exception $ignored) {
-        }
-    }
-
-    public function testFailingCase(): void
-    {
-        $file      = new DDC1509File();
-        $thumbnail = new DDC1509File();
-
-        $picture = new DDC1509Picture();
-        $picture->setFile($file);
-        $picture->setThumbnail($thumbnail);
-
-        $em = $this->_em;
-        assert($em instanceof EntityManager);
-        $em->persist($picture);
-        $em->flush();
-        $em->clear();
-
-        $id = $picture->getPictureId();
-
-        $pic = $em->merge($picture);
-        assert($pic instanceof DDC1509Picture);
-
-        self::assertNotNull($pic->getThumbnail());
-        self::assertNotNull($pic->getFile());
-    }
-}
-
-/**
- * @Entity
- */
-class DDC1509Picture
-{
-    /**
-     * @var int
-     * @Column(type="integer")
-     * @Id
-     * @GeneratedValue(strategy="AUTO")
-     */
-    private $id;
-
-    /**
-     * @var DDC1509AbstractFile
-     * @ManyToOne(targetEntity="DDC1509AbstractFile", cascade={"persist", "remove"})
-     */
-    private $thumbnail;
-
-    /**
-     * @var DDC1509AbstractFile|null
-     * @ManyToOne(targetEntity="DDC1509AbstractFile", cascade={"persist", "remove"})
-     */
-    private $file;
-
-    public function getPictureId(): int
-    {
-        return $this->id;
-    }
-
-    public function setFile(?DDC1509AbstractFile $value = null): void
-    {
-        $this->file = $value;
-    }
-
-    public function getFile(): ?DDC1509AbstractFile
-    {
-        return $this->file;
-    }
-
-    public function getThumbnail(): DDC1509AbstractFile
-    {
-        return $this->thumbnail;
-    }
-
-    public function setThumbnail(DDC1509AbstractFile $thumbnail): void
-    {
-        $this->thumbnail = $thumbnail;
-    }
-}
-
-/**
- * @Entity
- * @InheritanceType("SINGLE_TABLE")
- * @DiscriminatorColumn(name="discr", type="string")
- * @DiscriminatorMap({"abstractFile" = "DDC1509AbstractFile", "file" = "DDC1509File"})
- */
-class DDC1509AbstractFile
-{
-    /**
-     * @var int
-     * @Column(type="integer")
-     * @Id
-     * @GeneratedValue(strategy="AUTO")
-     */
-    public $id;
-
-    public function getFileId(): int
-    {
-        return $this->id;
-    }
-}
-
-/**
- * @Entity
- */
-class DDC1509File extends DDC1509AbstractFile
-{
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1594Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1594Test.php
deleted file mode 100644
index d8e6fed7f0b..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1594Test.php
+++ /dev/null
@@ -1,46 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\Tests\Models\CMS\CmsUser;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-use function get_class;
-
-/**
- * @group DDC-1594
- */
-class DDC1594Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        $this->useModelSet('cms');
-        parent::setUp();
-    }
-
-    public function testIssue(): void
-    {
-        $user           = new CmsUser();
-        $user->status   = 'foo';
-        $user->username = 'foo';
-        $user->name     = 'foo';
-
-        $this->_em->persist($user);
-        $this->_em->flush();
-
-        $this->_em->clear();
-        $detachedUser         = clone $user;
-        $detachedUser->name   = 'bar';
-        $detachedUser->status = 'bar';
-
-        $newUser = $this->_em->getReference(get_class($user), $user->id);
-
-        $mergedUser = $this->_em->merge($detachedUser);
-
-        self::assertNotSame($mergedUser, $detachedUser);
-        self::assertEquals('bar', $detachedUser->getName());
-        self::assertEquals('bar', $mergedUser->getName());
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1734Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1734Test.php
deleted file mode 100644
index c5e776e1da0..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC1734Test.php
+++ /dev/null
@@ -1,88 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\ORM\Proxy\Proxy;
-use Doctrine\Tests\Models\CMS\CmsGroup;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-use function get_class;
-use function serialize;
-use function unserialize;
-
-class DDC1734Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        $this->useModelSet('cms');
-        parent::setUp();
-    }
-
-    /**
-     * This test is DDC-1734 minus the serialization, i.e. it works
-     *
-     * @group DDC-1734
-     */
-    public function testMergeWorksOnNonSerializedProxies(): void
-    {
-        $group = new CmsGroup();
-
-        $group->setName('Foo');
-        $this->_em->persist($group);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $proxy = $this->getProxy($group);
-
-        self::assertInstanceOf(Proxy::class, $proxy);
-        self::assertFalse($proxy->__isInitialized());
-
-        $this->_em->detach($proxy);
-        $this->_em->clear();
-
-        $proxy = $this->_em->merge($proxy);
-
-        self::assertEquals('Foo', $proxy->getName(), 'The entity is broken');
-    }
-
-    /**
-     * This test reproduces DDC-1734 which is:
-     * - A non-initialized proxy is detached and serialized (the identifier of the proxy is *not* serialized)
-     * - the object is deserialized and merged (to turn into an entity)
-     * - the entity is broken because it has no identifier and no field defined
-     *
-     * @group DDC-1734
-     */
-    public function testMergeWorksOnSerializedProxies(): void
-    {
-        $group = new CmsGroup();
-
-        $group->setName('Foo');
-        $this->_em->persist($group);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $proxy = $this->getProxy($group);
-
-        self::assertInstanceOf(Proxy::class, $proxy);
-        self::assertFalse($proxy->__isInitialized());
-
-        $this->_em->detach($proxy);
-        $serializedProxy = serialize($proxy);
-        $this->_em->clear();
-
-        $unserializedProxy = $this->_em->merge(unserialize($serializedProxy));
-        self::assertEquals('Foo', $unserializedProxy->getName(), 'The entity is broken');
-    }
-
-    private function getProxy(object $object): \Doctrine\Common\Proxy\Proxy
-    {
-        $metadataFactory = $this->_em->getMetadataFactory();
-        $className       = get_class($object);
-        $identifier      = $metadataFactory->getMetadataFor($className)->getIdentifierValues($object);
-
-        return $this->_em->getProxyFactory()->getProxy($className, $identifier);
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2230Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2230Test.php
index c8025dc6dc6..44d9155e020 100644
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2230Test.php
+++ b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2230Test.php
@@ -38,29 +38,6 @@ protected function setUp(): void
         }
     }
 
-    public function testNotifyTrackingNotCalledOnUninitializedProxies(): void
-    {
-        $insertedUser          = new DDC2230User();
-        $insertedUser->address = new DDC2230Address();
-
-        $this->_em->persist($insertedUser);
-        $this->_em->persist($insertedUser->address);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $user = $this->_em->find(DDC2230User::class, $insertedUser->id);
-
-        $this->_em->clear();
-
-        $mergedUser = $this->_em->merge($user);
-
-        $address = $mergedUser->address;
-        assert($address instanceof Proxy);
-
-        self::assertInstanceOf(Proxy::class, $address);
-        self::assertFalse($address->__isInitialized());
-    }
-
     public function testNotifyTrackingCalledOnProxyInitialization(): void
     {
         $insertedAddress = new DDC2230Address();
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2409Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2409Test.php
deleted file mode 100644
index cbd075f78d6..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2409Test.php
+++ /dev/null
@@ -1,74 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\ORM\UnitOfWork;
-use Doctrine\Tests\Models\CMS\CmsArticle;
-use Doctrine\Tests\Models\CMS\CmsUser;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-/**
- * @group DDC-2409
- */
-class DDC2409Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        $this->useModelSet('cms');
-        parent::setUp();
-    }
-
-    public function testIssue(): void
-    {
-        $em  = $this->_em;
-        $uow = $em->getUnitOfWork();
-
-        $originalArticle = new CmsArticle();
-        $originalUser    = new CmsUser();
-
-        $originalArticle->topic = 'Unit Test';
-        $originalArticle->text  = 'How to write a test';
-
-        $originalUser->name     = 'Doctrine Bot';
-        $originalUser->username = 'DoctrineBot';
-        $originalUser->status   = 'active';
-
-        $originalUser->addArticle($originalArticle);
-
-        $em->persist($originalUser);
-        $em->persist($originalArticle);
-        $em->flush();
-        $em->clear();
-
-        $article = $em->find(CmsArticle::class, $originalArticle->id);
-        $user    = new CmsUser();
-
-        $user->name     = 'Doctrine Bot 2.0';
-        $user->username = 'BotDoctrine2';
-        $user->status   = 'new';
-
-        $article->setAuthor($user);
-
-        self::assertEquals(UnitOfWork::STATE_DETACHED, $uow->getEntityState($originalArticle));
-        self::assertEquals(UnitOfWork::STATE_DETACHED, $uow->getEntityState($originalUser));
-        self::assertEquals(UnitOfWork::STATE_MANAGED, $uow->getEntityState($article));
-        self::assertEquals(UnitOfWork::STATE_NEW, $uow->getEntityState($user));
-
-        $em->clear();
-
-        $userMerged    = $em->merge($user);
-        $articleMerged = $em->merge($article);
-
-        self::assertEquals(UnitOfWork::STATE_NEW, $uow->getEntityState($user));
-        self::assertEquals(UnitOfWork::STATE_DETACHED, $uow->getEntityState($article));
-        self::assertEquals(UnitOfWork::STATE_MANAGED, $uow->getEntityState($userMerged));
-        self::assertEquals(UnitOfWork::STATE_MANAGED, $uow->getEntityState($articleMerged));
-
-        self::assertNotSame($user, $userMerged);
-        self::assertNotSame($article, $articleMerged);
-        self::assertNotSame($userMerged, $articleMerged->user);
-        self::assertSame($user, $articleMerged->user);
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2645Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2645Test.php
deleted file mode 100644
index 4e12ee95fe5..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC2645Test.php
+++ /dev/null
@@ -1,78 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\ORM\Mapping\Column;
-use Doctrine\ORM\Mapping\Entity;
-use Doctrine\ORM\Mapping\GeneratedValue;
-use Doctrine\ORM\Mapping\Id;
-use Doctrine\ORM\Mapping\ManyToOne;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-/**
- * @group DDC-2645
- */
-class DDC2645Test extends OrmFunctionalTestCase
-{
-    public function testIssue(): void
-    {
-        $bar     = new DDC2645Bar();
-        $bar->id = 123;
-
-        $foo  = new DDC2645Foo(1, $bar, 'Foo');
-        $foo2 = new DDC2645Foo(1, $bar, 'Bar');
-
-        $this->_em->persist($bar);
-        $this->_em->persist($foo);
-
-        $foo3 = $this->_em->merge($foo2);
-
-        self::assertSame($foo, $foo3);
-        self::assertEquals('Bar', $foo->name);
-    }
-}
-
-/** @Entity */
-class DDC2645Foo
-{
-    /**
-     * @var int
-     * @Id
-     * @Column(type="integer")
-     */
-    private $id;
-
-    /**
-     * @var DDC2645Bar
-     * @Id
-     * @ManyToOne(targetEntity="DDC2645Bar")
-     */
-    private $bar;
-
-    /**
-     * @var string
-     * @Column
-     */
-    public $name;
-
-    public function __construct(int $id, DDC2645Bar $bar, string $name)
-    {
-        $this->id   = $id;
-        $this->bar  = $bar;
-        $this->name = $name;
-    }
-}
-
-/** @Entity */
-class DDC2645Bar
-{
-    /**
-     * @var int
-     * @Id
-     * @Column(type="integer")
-     * @GeneratedValue(strategy="NONE")
-     */
-    public $id;
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC3699Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC3699Test.php
deleted file mode 100644
index 5d002ef01a9..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC3699Test.php
+++ /dev/null
@@ -1,108 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\Tests\Models\DDC3699\DDC3699Child;
-use Doctrine\Tests\Models\DDC3699\DDC3699RelationMany;
-use Doctrine\Tests\Models\DDC3699\DDC3699RelationOne;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-use function assert;
-
-/**
- * @group DDC-3699
- */
-class DDC3699Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        $this->useModelSet('ddc3699');
-
-        parent::setUp();
-    }
-
-    /**
-     * @group DDC-3699
-     */
-    public function testMergingParentClassFieldsDoesNotStopMergingScalarFieldsForToOneUninitializedAssociations(): void
-    {
-        $id = 1;
-
-        $child = new DDC3699Child();
-
-        $child->id          = $id;
-        $child->childField  = 'childValue';
-        $child->parentField = 'parentValue';
-
-        $relation = new DDC3699RelationOne();
-
-        $relation->id       = $id;
-        $relation->child    = $child;
-        $child->oneRelation = $relation;
-
-        $this->_em->persist($relation);
-        $this->_em->persist($child);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $unManagedChild = $this->_em->find(DDC3699Child::class, $id);
-        assert($unManagedChild instanceof DDC3699Child);
-
-        $this->_em->detach($unManagedChild);
-
-        // make it managed again
-        $this->_em->find(DDC3699Child::class, $id);
-
-        $unManagedChild->childField  = 'modifiedChildValue';
-        $unManagedChild->parentField = 'modifiedParentValue';
-
-        $mergedChild = $this->_em->merge($unManagedChild);
-        assert($mergedChild instanceof DDC3699Child);
-
-        self::assertSame($mergedChild->childField, 'modifiedChildValue');
-        self::assertSame($mergedChild->parentField, 'modifiedParentValue');
-    }
-
-    /**
-     * @group DDC-3699
-     */
-    public function testMergingParentClassFieldsDoesNotStopMergingScalarFieldsForToManyUninitializedAssociations(): void
-    {
-        $id = 2;
-
-        $child = new DDC3699Child();
-
-        $child->id          = $id;
-        $child->childField  = 'childValue';
-        $child->parentField = 'parentValue';
-
-        $relation = new DDC3699RelationMany();
-
-        $relation->id       = $id;
-        $relation->child    = $child;
-        $child->relations[] = $relation;
-
-        $this->_em->persist($relation);
-        $this->_em->persist($child);
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $unmanagedChild = $this->_em->find(DDC3699Child::class, $id);
-        assert($unmanagedChild instanceof DDC3699Child);
-        $this->_em->detach($unmanagedChild);
-
-        // make it managed again
-        $this->_em->find(DDC3699Child::class, $id);
-
-        $unmanagedChild->childField  = 'modifiedChildValue';
-        $unmanagedChild->parentField = 'modifiedParentValue';
-
-        $mergedChild = $this->_em->merge($unmanagedChild);
-        assert($mergedChild instanceof DDC3699Child);
-
-        self::assertSame($mergedChild->childField, 'modifiedChildValue');
-        self::assertSame($mergedChild->parentField, 'modifiedParentValue');
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC501Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC501Test.php
deleted file mode 100644
index 7abdfcaafbc..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC501Test.php
+++ /dev/null
@@ -1,112 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\Tests\Models\CMS\CmsGroup;
-use Doctrine\Tests\Models\CMS\CmsPhonenumber;
-use Doctrine\Tests\Models\CMS\CmsUser;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-use function count;
-use function serialize;
-use function unserialize;
-
-class DDC501Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        $this->useModelSet('cms');
-        parent::setUp();
-    }
-
-    public function testMergeUnitializedManyToManyAndOneToManyCollections(): void
-    {
-        // Create User
-        $user = $this->createAndPersistUser();
-        $this->_em->flush();
-
-        self::assertTrue($this->_em->contains($user));
-        $this->_em->clear();
-        self::assertFalse($this->_em->contains($user));
-
-        unset($user);
-
-        // Reload User from DB *without* any associations (i.e. an uninitialized PersistantCollection)
-        $userReloaded = $this->loadUserFromEntityManager();
-
-        self::assertTrue($this->_em->contains($userReloaded));
-        $this->_em->clear();
-        self::assertFalse($this->_em->contains($userReloaded));
-
-        // freeze and unfreeze
-        $userClone = unserialize(serialize($userReloaded));
-        self::assertInstanceOf(CmsUser::class, $userClone);
-
-        // detached user can't know about his phonenumbers
-        self::assertEquals(0, count($userClone->getPhonenumbers()));
-        self::assertFalse($userClone->getPhonenumbers()->isInitialized(), 'User::phonenumbers should not be marked initialized.');
-
-        // detached user can't know about his groups either
-        self::assertEquals(0, count($userClone->getGroups()));
-        self::assertFalse($userClone->getGroups()->isInitialized(), 'User::groups should not be marked initialized.');
-
-        // Merge back and flush
-        $userClone = $this->_em->merge($userClone);
-
-        // Back in managed world I would expect to have my phonenumbers back but they aren't!
-    // Remember I didn't touch (and probably didn't need) them at all while in detached mode.
-        self::assertEquals(4, count($userClone->getPhonenumbers()), 'Phonenumbers are not available anymore');
-
-        // This works fine as long as cmUser::groups doesn't cascade "merge"
-        self::assertEquals(2, count($userClone->getGroups()));
-
-        $this->_em->flush();
-        $this->_em->clear();
-
-        self::assertFalse($this->_em->contains($userClone));
-
-        // Reload user from DB
-        $userFromEntityManager = $this->loadUserFromEntityManager();
-
-        //Strange: Now the phonenumbers are back again
-        self::assertEquals(4, count($userFromEntityManager->getPhonenumbers()));
-
-        // This works fine as long as cmUser::groups doesn't cascade "merge"
-        // Otherwise group memberships are physically deleted now!
-        self::assertEquals(2, count($userClone->getGroups()));
-    }
-
-    protected function createAndPersistUser(): CmsUser
-    {
-        $user           = new CmsUser();
-        $user->name     = 'Luka';
-        $user->username = 'lukacho';
-        $user->status   = 'developer';
-
-        foreach ([1111, 2222, 3333, 4444] as $number) {
-            $phone              = new CmsPhonenumber();
-            $phone->phonenumber = $number;
-            $user->addPhonenumber($phone);
-        }
-
-        foreach (['Moshers', 'Headbangers'] as $groupName) {
-            $group = new CmsGroup();
-            $group->setName($groupName);
-            $user->addGroup($group);
-        }
-
-        $this->_em->persist($user);
-
-        return $user;
-    }
-
-    protected function loadUserFromEntityManager(): CmsUser
-    {
-        return $this->_em
-                ->createQuery('SELECT u FROM Doctrine\Tests\Models\CMS\CmsUser u WHERE u.name like :name')
-                ->setParameter('name', 'Luka')
-                ->getSingleResult();
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC518Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC518Test.php
deleted file mode 100644
index f1ef8b0e6f8..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC518Test.php
+++ /dev/null
@@ -1,41 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\Tests\Models\CMS\CmsArticle;
-use Doctrine\Tests\Models\CMS\CmsUser;
-use Doctrine\Tests\OrmFunctionalTestCase;
-
-class DDC518Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        $this->useModelSet('cms');
-        parent::setUp();
-    }
-
-    public function testMergeWithRelatedNew(): void
-    {
-        $article        = new CmsArticle();
-        $article->text  = 'foo';
-        $article->topic = 'bar';
-
-        $this->_em->persist($article);
-        $this->_em->flush();
-        $this->_em->detach($article);
-        $this->_em->clear();
-
-        $user           = new CmsUser();
-        $user->username = 'beberlei';
-        $user->name     = 'Benjamin Eberlei';
-        $user->status   = 'active';
-        $article->user  = $user;
-
-        $this->_em->persist($user);
-        $managedArticle = $this->_em->merge($article);
-
-        self::assertSame($article->user, $managedArticle->user);
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC729Test.php b/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC729Test.php
deleted file mode 100644
index 3754508b175..00000000000
--- a/tests/Doctrine/Tests/ORM/Functional/Ticket/DDC729Test.php
+++ /dev/null
@@ -1,213 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Functional\Ticket;
-
-use Doctrine\Common\Collections\ArrayCollection;
-use Doctrine\Common\Collections\Collection;
-use Doctrine\ORM\Mapping\Column;
-use Doctrine\ORM\Mapping\Entity;
-use Doctrine\ORM\Mapping\GeneratedValue;
-use Doctrine\ORM\Mapping\Id;
-use Doctrine\ORM\Mapping\ManyToMany;
-use Doctrine\ORM\PersistentCollection;
-use Doctrine\ORM\Tools\SchemaTool;
-use Doctrine\Tests\OrmFunctionalTestCase;
-use Exception;
-
-use function count;
-
-class DDC729Test extends OrmFunctionalTestCase
-{
-    protected function setUp(): void
-    {
-        parent::setUp();
-
-        try {
-            $schemaTool = new SchemaTool($this->_em);
-            $schemaTool->createSchema(
-                [
-                    $this->_em->getClassMetadata(DDC729A::class),
-                    $this->_em->getClassMetadata(DDC729B::class),
-                ]
-            );
-        } catch (Exception $e) {
-        }
-    }
-
-    public function testMergeManyToMany(): void
-    {
-        $a            = new DDC729A();
-        $b            = new DDC729B();
-        $a->related[] = $b;
-
-        $this->_em->persist($a);
-        $this->_em->persist($b);
-        $this->_em->flush();
-        $this->_em->clear();
-        $aId = $a->id;
-
-        $a     = new DDC729A();
-        $a->id = $aId;
-
-        self::assertInstanceOf(ArrayCollection::class, $a->related);
-
-        $a = $this->_em->merge($a);
-
-        self::assertInstanceOf(PersistentCollection::class, $a->related);
-
-        self::assertFalse($a->related->isInitialized(), 'Collection should not be marked initialized.');
-        self::assertFalse($a->related->isDirty(), 'Collection should not be marked as dirty.');
-
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $a = $this->_em->find(DDC729A::class, $aId);
-        self::assertEquals(1, count($a->related));
-    }
-
-    public function testUnidirectionalMergeManyToMany(): void
-    {
-        $a            = new DDC729A();
-        $b1           = new DDC729B();
-        $b2           = new DDC729B();
-        $a->related[] = $b1;
-
-        $this->_em->persist($a);
-        $this->_em->persist($b1);
-        $this->_em->persist($b2);
-        $this->_em->flush();
-        $this->_em->clear();
-        $aId = $a->id;
-
-        $a     = new DDC729A();
-        $a->id = $aId;
-
-        $a = $this->_em->merge($a);
-
-        $a->related->set(0, $this->_em->merge($b1));
-
-        $a->related->set(1, $this->_em->merge($b2));
-
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $a = $this->_em->find(DDC729A::class, $aId);
-        self::assertEquals(2, count($a->related));
-    }
-
-    public function testBidirectionalMergeManyToMany(): void
-    {
-        $a            = new DDC729A();
-        $b1           = new DDC729B();
-        $b2           = new DDC729B();
-        $a->related[] = $b1;
-
-        $this->_em->persist($a);
-        $this->_em->persist($b1);
-        $this->_em->persist($b2);
-        $this->_em->flush();
-        $this->_em->clear();
-        $aId = $a->id;
-
-        $a     = new DDC729A();
-        $a->id = $aId;
-
-        $a = $this->_em->merge($a);
-
-        $a->related->set(0, $this->_em->merge($b1));
-        $b1->related->set(0, $a);
-
-        $a->related->set(1, $this->_em->merge($b2));
-        $b2->related->set(0, $a);
-
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $a = $this->_em->find(DDC729A::class, $aId);
-        self::assertEquals(2, count($a->related));
-    }
-
-    public function testBidirectionalMultiMergeManyToMany(): void
-    {
-        $a            = new DDC729A();
-        $b1           = new DDC729B();
-        $b2           = new DDC729B();
-        $a->related[] = $b1;
-
-        $this->_em->persist($a);
-        $this->_em->persist($b1);
-        $this->_em->persist($b2);
-        $this->_em->flush();
-        $this->_em->clear();
-        $aId = $a->id;
-
-        $a     = new DDC729A();
-        $a->id = $aId;
-
-        $a = $this->_em->merge($a);
-
-        $a->related->set(0, $this->_em->merge($b1));
-        $b1->related->set(0, $this->_em->merge($a));
-
-        $a->related->set(1, $this->_em->merge($b2));
-        $b2->related->set(0, $this->_em->merge($a));
-
-        $this->_em->flush();
-        $this->_em->clear();
-
-        $a = $this->_em->find(DDC729A::class, $aId);
-        self::assertEquals(2, count($a->related));
-    }
-}
-
-/**
- * @Entity
- */
-class DDC729A
-{
-    /**
-     * @var int
-     * @Id
-     * @GeneratedValue
-     * @Column(type="integer")
-     */
-    public $id;
-
-    /**
-     * @psalm-var Collection<int, DDC729B>
-     * @ManyToMany(targetEntity="DDC729B", inversedBy="related")
-     */
-    public $related;
-
-    public function __construct()
-    {
-        $this->related = new ArrayCollection();
-    }
-}
-
-/**
- * @Entity
- */
-class DDC729B
-{
-    /**
-     * @var int
-     * @Id
-     * @GeneratedValue
-     * @Column(type="integer")
-     */
-    public $id;
-
-    /**
-     * @psalm-var Collection<int, DDC729B>
-     * @ManyToMany(targetEntity="DDC729B", mappedBy="related")
-     */
-    public $related;
-
-    public function __construct()
-    {
-        $this->related = new ArrayCollection();
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/Mapping/Reflection/ReflectionPropertiesGetterTest.php b/tests/Doctrine/Tests/ORM/Mapping/Reflection/ReflectionPropertiesGetterTest.php
deleted file mode 100644
index d608b939efc..00000000000
--- a/tests/Doctrine/Tests/ORM/Mapping/Reflection/ReflectionPropertiesGetterTest.php
+++ /dev/null
@@ -1,134 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Doctrine\Tests\ORM\Mapping\Reflection;
-
-use Doctrine\ORM\Mapping\Reflection\ReflectionPropertiesGetter;
-use Doctrine\Persistence\Mapping\ReflectionService;
-use Doctrine\Persistence\Mapping\RuntimeReflectionService;
-use Doctrine\Tests\Models\Reflection\ClassWithMixedProperties;
-use Doctrine\Tests\Models\Reflection\ParentClass;
-use PHPUnit\Framework\MockObject\MockObject;
-use PHPUnit\Framework\TestCase;
-use ReflectionClass;
-
-use function assert;
-
-/**
- * Tests for {@see \Doctrine\ORM\Mapping\Reflection\ReflectionPropertiesGetter}
- *
- * @covers \Doctrine\ORM\Mapping\Reflection\ReflectionPropertiesGetter
- */
-class ReflectionPropertiesGetterTest extends TestCase
-{
-    public function testRetrievesProperties(): void
-    {
-        $properties = (new ReflectionPropertiesGetter(new RuntimeReflectionService()))
-            ->getProperties(ClassWithMixedProperties::class);
-
-        self::assertCount(5, $properties);
-
-        foreach ($properties as $property) {
-            self::assertInstanceOf('ReflectionProperty', $property);
-        }
-    }
-
-    public function testRetrievedInstancesAreNotStatic(): void
-    {
-        $properties = (new ReflectionPropertiesGetter(new RuntimeReflectionService()))
-            ->getProperties(ClassWithMixedProperties::class);
-
-        foreach ($properties as $property) {
-            self::assertFalse($property->isStatic());
-        }
-    }
-
-    public function testExpectedKeys(): void
-    {
-        $properties = (new ReflectionPropertiesGetter(new RuntimeReflectionService()))
-            ->getProperties(ClassWithMixedProperties::class);
-
-        self::assertArrayHasKey(
-            "\0" . ClassWithMixedProperties::class . "\0" . 'privateProperty',
-            $properties
-        );
-        self::assertArrayHasKey(
-            "\0" . ClassWithMixedProperties::class . "\0" . 'privatePropertyOverride',
-            $properties
-        );
-        self::assertArrayHasKey(
-            "\0" . ParentClass::class . "\0" . 'privatePropertyOverride',
-            $properties
-        );
-        self::assertArrayHasKey(
-            "\0*\0protectedProperty",
-            $properties
-        );
-        self::assertArrayHasKey(
-            'publicProperty',
-            $properties
-        );
-    }
-
-    public function testPropertiesAreAccessible(): void
-    {
-        $object     = new ClassWithMixedProperties();
-        $properties = (new ReflectionPropertiesGetter(new RuntimeReflectionService()))
-            ->getProperties(ClassWithMixedProperties::class);
-
-        foreach ($properties as $property) {
-            self::assertSame($property->getName(), $property->getValue($object));
-        }
-    }
-
-    public function testPropertyGetterIsIdempotent(): void
-    {
-        $getter = (new ReflectionPropertiesGetter(new RuntimeReflectionService()));
-
-        self::assertSame(
-            $getter->getProperties(ClassWithMixedProperties::class),
-            $getter->getProperties(ClassWithMixedProperties::class)
-        );
-    }
-
-    public function testPropertyGetterWillSkipPropertiesNotRetrievedByTheRuntimeReflectionService(): void
-    {
-        $reflectionService = $this->createMock(ReflectionService::class);
-        assert($reflectionService instanceof ReflectionService || $reflectionService instanceof MockObject);
-
-        $reflectionService
-            ->expects(self::exactly(2))
-            ->method('getClass')
-            ->with(self::logicalOr(ClassWithMixedProperties::class, ParentClass::class))
-            ->will(self::returnValueMap([
-                [ClassWithMixedProperties::class, new ReflectionClass(ClassWithMixedProperties::class)],
-                [ParentClass::class, new ReflectionClass(ParentClass::class)],
-            ]));
-
-        $reflectionService
-            ->expects(self::atLeastOnce())
-            ->method('getAccessibleProperty');
-
-        $getter = (new ReflectionPropertiesGetter($reflectionService));
-
-        self::assertEmpty($getter->getProperties(ClassWithMixedProperties::class));
-    }
-
-    public function testPropertyGetterWillSkipClassesNotRetrievedByTheRuntimeReflectionService(): void
-    {
-        $reflectionService = $this->createMock(ReflectionService::class);
-        assert($reflectionService instanceof ReflectionService || $reflectionService instanceof MockObject);
-
-        $reflectionService
-            ->expects(self::once())
-            ->method('getClass')
-            ->with(ClassWithMixedProperties::class);
-
-        $reflectionService->expects(self::never())->method('getAccessibleProperty');
-
-        $getter = (new ReflectionPropertiesGetter($reflectionService));
-
-        self::assertEmpty($getter->getProperties(ClassWithMixedProperties::class));
-    }
-}
diff --git a/tests/Doctrine/Tests/ORM/UnitOfWorkTest.php b/tests/Doctrine/Tests/ORM/UnitOfWorkTest.php
index e8b07733d79..84e9f064eb3 100644
--- a/tests/Doctrine/Tests/ORM/UnitOfWorkTest.php
+++ b/tests/Doctrine/Tests/ORM/UnitOfWorkTest.php
@@ -11,7 +11,6 @@
 use Doctrine\DBAL\Driver;
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\ORM\EntityNotFoundException;
-use Doctrine\ORM\Events;
 use Doctrine\ORM\Mapping\ClassMetadata;
 use Doctrine\ORM\Mapping\Column;
 use Doctrine\ORM\Mapping\Entity;
@@ -23,7 +22,6 @@
 use Doctrine\ORM\OptimisticLockException;
 use Doctrine\ORM\ORMInvalidArgumentException;
 use Doctrine\ORM\UnitOfWork;
-use Doctrine\Persistence\Event\LifecycleEventArgs;
 use Doctrine\Persistence\NotifyPropertyChanged;
 use Doctrine\Persistence\PropertyChangedListener;
 use Doctrine\Tests\Mocks\ConnectionMock;
@@ -31,15 +29,12 @@
 use Doctrine\Tests\Mocks\EntityPersisterMock;
 use Doctrine\Tests\Mocks\UnitOfWorkMock;
 use Doctrine\Tests\Models\CMS\CmsPhonenumber;
-use Doctrine\Tests\Models\CMS\CmsUser;
 use Doctrine\Tests\Models\Forum\ForumAvatar;
 use Doctrine\Tests\Models\Forum\ForumUser;
 use Doctrine\Tests\OrmTestCase;
 use PHPUnit\Framework\MockObject\MockObject;
 use stdClass;
 
-use function assert;
-use function gc_collect_cycles;
 use function get_class;
 use function method_exists;
 use function random_int;
@@ -472,115 +467,6 @@ public function entitiesWithInvalidIdentifiersProvider(): array
         ];
     }
 
-    /**
-     * @group 5689
-     * @group 1465
-     */
-    public function testObjectHashesOfMergedEntitiesAreNotUsedInOriginalEntityDataMap(): void
-    {
-        $user       = new CmsUser();
-        $user->name = 'ocramius';
-        $mergedUser = $this->_unitOfWork->merge($user);
-
-        self::assertSame([], $this->_unitOfWork->getOriginalEntityData($user), 'No original data was stored');
-        self::assertSame([], $this->_unitOfWork->getOriginalEntityData($mergedUser), 'No original data was stored');
-
-        $user       = null;
-        $mergedUser = null;
-
-        // force garbage collection of $user (frees the used object hashes, which may be recycled)
-        gc_collect_cycles();
-
-        $newUser       = new CmsUser();
-        $newUser->name = 'ocramius';
-
-        $this->_unitOfWork->persist($newUser);
-
-        self::assertSame([], $this->_unitOfWork->getOriginalEntityData($newUser), 'No original data was stored');
-    }
-
-    /**
-     * @group DDC-1955
-     * @group 5570
-     * @group 6174
-     */
-    public function testMergeWithNewEntityWillPersistItAndTriggerPrePersistListenersWithMergedEntityData(): void
-    {
-        $entity = new EntityWithRandomlyGeneratedField();
-
-        $generatedFieldValue = $entity->generatedField;
-
-        $this
-            ->eventManager
-            ->expects(self::any())
-            ->method('hasListeners')
-            ->willReturnCallback(static function ($eventName) {
-                return $eventName === Events::prePersist;
-            });
-        $this
-            ->eventManager
-            ->expects(self::once())
-            ->method('dispatchEvent')
-            ->with(
-                self::anything(),
-                self::callback(static function (LifecycleEventArgs $args) use ($entity, $generatedFieldValue) {
-                    $object = $args->getObject();
-                    assert($object instanceof EntityWithRandomlyGeneratedField);
-
-                    self::assertInstanceOf(EntityWithRandomlyGeneratedField::class, $object);
-                    self::assertNotSame($entity, $object);
-                    self::assertSame($generatedFieldValue, $object->generatedField);
-
-                    return true;
-                })
-            );
-
-        $object = $this->_unitOfWork->merge($entity);
-        assert($object instanceof EntityWithRandomlyGeneratedField);
-
-        self::assertNotSame($object, $entity);
-        self::assertInstanceOf(EntityWithRandomlyGeneratedField::class, $object);
-        self::assertSame($object->generatedField, $entity->generatedField);
-    }
-
-    /**
-     * @group DDC-1955
-     * @group 5570
-     * @group 6174
-     */
-    public function testMergeWithExistingEntityWillNotPersistItNorTriggerPrePersistListeners(): void
-    {
-        $persistedEntity = new EntityWithRandomlyGeneratedField();
-        $mergedEntity    = new EntityWithRandomlyGeneratedField();
-
-        $mergedEntity->id             = $persistedEntity->id;
-        $mergedEntity->generatedField = random_int(
-            $persistedEntity->generatedField + 1,
-            $persistedEntity->generatedField + 1000
-        );
-
-        $this
-            ->eventManager
-            ->expects(self::any())
-            ->method('hasListeners')
-            ->willReturnCallback(static function ($eventName) {
-                return $eventName === Events::prePersist;
-            });
-        $this->eventManager->expects(self::never())->method('dispatchEvent');
-
-        $this->_unitOfWork->registerManaged(
-            $persistedEntity,
-            ['id' => $persistedEntity->id],
-            ['generatedField' => $persistedEntity->generatedField]
-        );
-
-        $merged = $this->_unitOfWork->merge($mergedEntity);
-        assert($merged instanceof EntityWithRandomlyGeneratedField);
-
-        self::assertSame($merged, $persistedEntity);
-        self::assertSame($persistedEntity->generatedField, $mergedEntity->generatedField);
-    }
-
     /**
      * Unlike next test, this one demonstrates that the problem does
      * not necessarily reproduce if all the pieces are being flushed together.