Use server version as FCV when connected to mongos

tests/FunctionalTestCase.php

@@ -8,6 +8,7 @@ use MongoDB\Driver\Manager;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Query;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Exception\CommandException;
 use stdClass;
 use UnexpectedValueException;
 
@@ -49,6 +50,10 @@ abstract class FunctionalTestCase extends TestCase
 
     protected function getFeatureCompatibilityVersion(ReadPreference $readPreference = null)
     {
+        if ($this->isShardedCluster()) {
+            return $this->getServerVersion($readPreference);
+        }
+
         if (version_compare($this->getServerVersion(), '3.4.0', '<')) {
             return $this->getServerVersion($readPreference);
         }
@@ -115,6 +120,15 @@ abstract class FunctionalTestCase extends TestCase
         throw new UnexpectedValueException('Could not determine server storage engine');
     }
 
+    protected function isShardedCluster()
+    {
+        if ($this->getPrimaryServer()->getType() == Server::TYPE_MONGOS) {
+            return true;
+        }
+
+        return false;
+    }
+
     protected function isShardedClusterUsingReplicasets()
     {
         $cursor = $this->getPrimaryServer()->executeQuery(
@@ -195,7 +209,7 @@ abstract class FunctionalTestCase extends TestCase
         }
 
         // TODO: MongoDB 4.2 should support sharded clusters (see: PHPLIB-374)
-        if ($this->getPrimaryServer()->getType() === Server::TYPE_MONGOS) {
+        if ($this->isShardedCluster()) {
             $this->markTestSkipped('Transactions are not supported on sharded clusters');
         }
 

tests/Operation/ModifyCollectionFunctionalTest.php

@@ -21,7 +21,7 @@ class ModifyCollectionFunctionalTest extends FunctionalTestCase
             $this->getDatabaseName(),
             $this->getCollectionName(),
             ['index' => ['keyPattern' => ['lastAccess' => 1], 'expireAfterSeconds' => 1000]],
-            ['typeMap' => ['root' => 'array']]
+            ['typeMap' => ['root' => 'array', 'document' => 'array']]
         );
         $result = $modifyCollection->execute($this->getPrimaryServer());
 
@@ -30,8 +30,6 @@ class ModifyCollectionFunctionalTest extends FunctionalTestCase
              * non-primary shards that don't have chunks for the collection, the result contains a
              * "ns does not exist" error. */
             foreach ($result['raw'] as $shard) {
-                $shard = (array) $shard;
-
                 if (array_key_exists('ok', $shard) && $shard['ok'] == 1) {
                     $this->assertSame(3, $shard['expireAfterSeconds_old']);
                     $this->assertSame(1000, $shard['expireAfterSeconds_new']);