Use w:majority for operations in change stream tests

This will avoid spurious test failures due to timing and ensure that each acknowledged write is returned in the next change stream iteration.

tests/Operation/WatchFunctionalTest.php

@@ -7,6 +7,7 @@ use MongoDB\BSON\TimestampInterface;
 use MongoDB\Driver\Manager;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\ConnectionTimeoutException;
 use MongoDB\Driver\Exception\LogicException;
 use MongoDB\Exception\ResumeTokenException;
@@ -1026,7 +1027,12 @@ class WatchFunctionalTest extends FunctionalTestCase
 
     private function insertDocument($document)
     {
-        $insertOne = new InsertOne($this->getDatabaseName(), $this->getCollectionName(), $document);
+        $insertOne = new InsertOne(
+            $this->getDatabaseName(),
+            $this->getCollectionName(),
+            $document,
+            ['writeConcern' => new WriteConcern(WriteConcern::MAJORITY)]
+        );
         $writeResult = $insertOne->execute($this->getPrimaryServer());
         $this->assertEquals(1, $writeResult->getInsertedCount());
     }

tests/SpecTests/Operation.php

@@ -6,6 +6,7 @@ use MongoDB\Collection;
 use MongoDB\Database;
 use MongoDB\Driver\Cursor;
 use MongoDB\Driver\Session;
+use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\BulkWriteException;
 use MongoDB\Driver\Exception\Exception;
 use MongoDB\Operation\FindOneAndReplace;
@@ -53,6 +54,11 @@ final class Operation
     {
         $o = new self($operation);
 
+        /* Note: change streams only return majority-committed writes, so ensure
+         * each operation applies that write concern. This will avoid spurious
+         * test failures. */
+        $writeConcern = new WriteConcern(WriteConcern::MAJORITY);
+
         // Expect all operations to succeed
         $o->errorExpectation = ErrorExpectation::noError();
 
@@ -66,6 +72,8 @@ final class Operation
             $o->arguments = ['command' => [
                 'renameCollection' => $operation->database . '.' . $operation->collection,
                 'to' => $operation->database . '.' . $operation->arguments->to,
+                // Note: Database::command() does not inherit WC, so be explicit
+                'writeConcern' => $writeConcern,
             ]];
 
             return $o;
@@ -73,6 +81,7 @@ final class Operation
 
         $o->databaseName = $operation->database;
         $o->collectionName = $operation->collection;
+        $o->collectionOptions = ['writeConcern' => $writeConcern];
         $o->object = self::OBJECT_SELECT_COLLECTION;
 
         return $o;