Fixes changeset being empty when datetime change is sub second (#2676)

* Update UnitOfWork.php

* Add test (and remove fix to see failure)

* Add comment

* add fix

* phpcs & use fix

* fix typo

* Fix phpcs

Author: magnetik

lib/Doctrine/ODM/MongoDB/UnitOfWork.php

@@ -24,7 +24,6 @@
 use Doctrine\Persistence\NotifyPropertyChanged;
 use Doctrine\Persistence\PropertyChangedListener;
 use InvalidArgumentException;
-use MongoDB\BSON\UTCDateTime;
 use MongoDB\Driver\Exception\RuntimeException;
 use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
@@ -835,10 +834,9 @@ private function computeOrRecomputeChangeSet(ClassMetadata $class, object $docum
                     $dbOrgValue    = $dateType->convertToDatabaseValue($orgValue);
                     $dbActualValue = $dateType->convertToDatabaseValue($actualValue);
 
-                    $orgTimestamp    = $dbOrgValue instanceof UTCDateTime ? $dbOrgValue->toDateTime()->getTimestamp() : null;
-                    $actualTimestamp = $dbActualValue instanceof UTCDateTime ? $dbActualValue->toDateTime()->getTimestamp() : null;
-
-                    if ($orgTimestamp === $actualTimestamp) {
+                    // We rely on loose comparison to compare every field (including microseconds)
+                    // phpcs:ignore SlevomatCodingStandard.Operators.DisallowEqualOperators.DisallowedEqualOperator
+                    if ($dbOrgValue == $dbActualValue) {
                         continue;
                     }
                 }

tests/Doctrine/ODM/MongoDB/Tests/Functional/DateTest.php

@@ -69,6 +69,21 @@ public static function provideEquivalentDates(): array
         ];
     }
 
+    public function testDateInstanceChangeWhenValueDifferenceIsSubSecond(): void
+    {
+        $user = new User();
+        $user->setCreatedAt(new UTCDateTime(100000000000));
+        $this->dm->persist($user);
+        $this->dm->flush();
+        $this->dm->clear();
+
+        $user = $this->dm->getRepository($user::class)->findOneBy([]);
+        $user->setCreatedAt(new UTCDateTime(100000000123));
+        $this->dm->getUnitOfWork()->computeChangeSets();
+        $changeset = $this->dm->getUnitOfWork()->getDocumentChangeSet($user);
+        self::assertNotEmpty($changeset);
+    }
+
     public function testDateInstanceValueChangeDoesCauseUpdateIfValueIsTheSame(): void
     {
         $user = new User();