PHPLIB-302: Support session option for operations

docs/includes/apiargs-MongoDBClient-method-dropDatabase-option.yaml

+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBClient-method-listDatabases-option.yaml

 source:
   file: apiargs-common-option.yaml
   ref: maxTimeMS
+---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
 ...

docs/includes/apiargs-MongoDBCollection-method-aggregate-option.yaml

@@ -68,6 +68,10 @@ source:
 post: |
   This option will be ignored when using the :ref:`$out <agg-out>` stage.
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBCollection-method-bulkWrite-option.yaml

@@ -17,6 +17,10 @@ interface: phpmethod
 operation: ~
 optional: true
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-count-option.yaml

@@ -38,6 +38,10 @@ source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: readPreference
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 arg_name: option
 name: skip
 type: integer

docs/includes/apiargs-MongoDBCollection-method-createIndex-option.yaml

@@ -75,6 +75,10 @@ interface: phpmethod
 operation: ~
 optional: true
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-createIndexes-option.yaml

@@ -2,6 +2,10 @@ source:
   file: apiargs-common-option.yaml
   ref: maxTimeMS
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-deleteMany-option.yaml

@@ -2,6 +2,10 @@ source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: collation
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-deleteOne-option.yaml

@@ -2,6 +2,10 @@ source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: collation
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-distinct-option.yaml

@@ -13,4 +13,8 @@ source:
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: readPreference
+---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
 ...

docs/includes/apiargs-MongoDBCollection-method-drop-option.yaml

@@ -4,6 +4,10 @@ source:
 post: |
   This will be used for the returned command result document.
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-dropIndex-option.yaml

@@ -2,6 +2,10 @@ source:
   file: apiargs-common-option.yaml
   ref: maxTimeMS
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBCollection-method-dropIndexes-option.yaml

@@ -2,6 +2,10 @@ source:
   file: apiargs-common-option.yaml
   ref: maxTimeMS
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBCollection-method-find-option.yaml

@@ -125,6 +125,10 @@ source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: readPreference
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 arg_name: option
 name: max
 type: array|object

docs/includes/apiargs-MongoDBCollection-method-findOne-option.yaml

@@ -34,6 +34,10 @@ source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: readPreference
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBCollection-method-findOneAndDelete-option.yaml

@@ -14,6 +14,10 @@ source:
   file: apiargs-common-option.yaml
   ref: maxTimeMS
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBCollection-method-findOneAndReplace-option.yaml

@@ -31,6 +31,10 @@ interface: phpmethod
 operation: ~
 optional: true
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBCollection-method-findOneAndUpdate-option.yaml

@@ -35,6 +35,10 @@ interface: phpmethod
 operation: ~
 optional: true
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBCollection-method-insertMany-option.yaml

@@ -6,6 +6,10 @@ source:
   file: apiargs-MongoDBCollection-method-bulkWrite-option.yaml
   ref: ordered
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-insertOne-option.yaml

@@ -2,6 +2,10 @@ source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: bypassDocumentValidation
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-listIndexes-option.yaml

 source:
   file: apiargs-common-option.yaml
   ref: maxTimeMS
+---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
 ...

docs/includes/apiargs-MongoDBCollection-method-mapReduce-option.yaml

@@ -70,6 +70,10 @@ interface: phpmethod
 operation: ~
 optional: true
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-method-find-option.yaml
   ref: sort

docs/includes/apiargs-MongoDBCollection-method-replaceOne-option.yaml

@@ -10,6 +10,10 @@ source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: collation
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-updateMany-option.yaml

@@ -14,6 +14,10 @@ source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: collation
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBCollection-method-updateOne-option.yaml

@@ -10,6 +10,10 @@ source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: collation
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBCollection-common-option.yaml
   ref: writeConcern

docs/includes/apiargs-MongoDBDatabase-method-command-option.yaml

@@ -5,6 +5,10 @@ description: |
    :manual:`Read preference </reference/read-preference>` to use for the
    operation. Defaults to the database's read preference.
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBDatabase-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBDatabase-method-createCollection-option.yaml

@@ -93,6 +93,10 @@ source:
   file: apiargs-common-option.yaml
   ref: maxTimeMS
 ---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 arg_name: option
 name: size
 type: integer

docs/includes/apiargs-MongoDBDatabase-method-drop-option.yaml

+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBDatabase-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBDatabase-method-dropCollection-option.yaml

+source:
+  file: apiargs-common-option.yaml
+  ref: session
+---
 source:
   file: apiargs-MongoDBDatabase-common-option.yaml
   ref: typeMap

docs/includes/apiargs-MongoDBDatabase-method-listCollections-option.yaml

@@ -12,4 +12,8 @@ optional: true
 source:
   file: apiargs-common-option.yaml
   ref: maxTimeMS
+---
+source:
+  file: apiargs-common-option.yaml
+  ref: session
 ...

docs/includes/apiargs-common-option.yaml

@@ -36,6 +36,17 @@ replacement:
   parent: "client"
 ---
 arg_name: option
+name: session
+type: :php:`MongoDB\\Driver\\Session <class.mongodb-driver-session>`
+description: |
+  Client session to associate with the operation.
+
+  Sessions are not supported for server versions prior to 3.6.
+interface: phpmethod
+operation: ~
+optional: true
+---
+arg_name: option
 name: typeMap
 type: array
 description: |

src/Operation/Aggregate.php

@@ -21,6 +21,7 @@ use MongoDB\Driver\Command;
 use MongoDB\Driver\ReadConcern;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -93,6 +94,10 @@ class Aggregate implements Executable
      *
      *    This option is ignored if the $out stage is specified.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * typeMap (array): Type map for BSON deserialization. This will be
      *    applied to the returned Cursor (it is not sent to the server).
      *
@@ -175,6 +180,10 @@ class Aggregate implements Executable
             throw InvalidArgumentException::invalidType('"readPreference" option', $options['readPreference'], 'MongoDB\Driver\ReadPreference');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['typeMap']) && ! is_array($options['typeMap'])) {
             throw InvalidArgumentException::invalidType('"typeMap" option', $options['typeMap'], 'array');
         }
@@ -330,6 +339,10 @@ class Aggregate implements Executable
             $options['readPreference'] = $this->options['readPreference'];
         }
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         if ($hasOutStage && isset($this->options['writeConcern'])) {
             $options['writeConcern'] = $this->options['writeConcern'];
         }

src/Operation/BulkWrite.php

@@ -20,6 +20,7 @@ namespace MongoDB\Operation;
 use MongoDB\BulkWriteResult;
 use MongoDB\Driver\BulkWrite as Bulk;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -106,6 +107,10 @@ class BulkWrite implements Executable
      *    performing the remaining writes. If false, when a write fails,
      *    continue with the remaining writes, if any. The default is true.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * writeConcern (MongoDB\Driver\WriteConcern): Write concern.
      *
      * @param string  $databaseName   Database name
@@ -280,6 +285,10 @@ class BulkWrite implements Executable
             throw InvalidArgumentException::invalidType('"ordered" option', $options['ordered'], 'boolean');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['writeConcern']) && ! $options['writeConcern'] instanceof WriteConcern) {
             throw InvalidArgumentException::invalidType('"writeConcern" option', $options['writeConcern'], 'MongoDB\Driver\WriteConcern');
         }
@@ -343,9 +352,29 @@ class BulkWrite implements Executable
             }
         }
 
-        $writeConcern = isset($this->options['writeConcern']) ? $this->options['writeConcern'] : null;
-        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $writeConcern);
+        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $this->createOptions());
 
         return new BulkWriteResult($writeResult, $insertedIds);
     }
+
+    /**
+     * Create options for executing the bulk write.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executebulkwrite.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        if (isset($this->options['writeConcern'])) {
+            $options['writeConcern'] = $this->options['writeConcern'];
+        }
+
+        return $options;
+    }
 }

src/Operation/Count.php

@@ -21,6 +21,7 @@ use MongoDB\Driver\Command;
 use MongoDB\Driver\ReadConcern;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
 use MongoDB\Exception\UnexpectedValueException;
@@ -69,6 +70,10 @@ class Count implements Executable
      *
      *  * readPreference (MongoDB\Driver\ReadPreference): Read preference.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * skip (integer): The number of documents to skip before returning the
      *    documents.
      *
@@ -108,6 +113,10 @@ class Count implements Executable
             throw InvalidArgumentException::invalidType('"readPreference" option', $options['readPreference'], 'MongoDB\Driver\ReadPreference');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['skip']) && ! is_integer($options['skip'])) {
             throw InvalidArgumentException::invalidType('"skip" option', $options['skip'], 'integer');
         }
@@ -201,6 +210,10 @@ class Count implements Executable
             $options['readPreference'] = $this->options['readPreference'];
         }
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         return $options;
     }
 }

src/Operation/CreateCollection.php

@@ -19,6 +19,7 @@ namespace MongoDB\Operation;
 
 use MongoDB\Driver\Command;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -74,6 +75,10 @@ class CreateCollection implements Executable
      *  * maxTimeMS (integer): The maximum amount of time to allow the query to
      *    run.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * size (integer): The maximum number of bytes for a capped collection.
      *
      *  * storageEngine (document): Storage engine options.
@@ -129,6 +134,10 @@ class CreateCollection implements Executable
             throw InvalidArgumentException::invalidType('"maxTimeMS" option', $options['maxTimeMS'], 'integer');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['size']) && ! is_integer($options['size'])) {
             throw InvalidArgumentException::invalidType('"size" option', $options['size'], 'integer');
         }
@@ -228,6 +237,10 @@ class CreateCollection implements Executable
     {
         $options = [];
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         if (isset($this->options['writeConcern'])) {
             $options['writeConcern'] = $this->options['writeConcern'];
         }

src/Operation/CreateIndexes.php

@@ -20,6 +20,7 @@ namespace MongoDB\Operation;
 use MongoDB\Driver\BulkWrite as Bulk;
 use MongoDB\Driver\Command;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -53,6 +54,10 @@ class CreateIndexes implements Executable
      *  * maxTimeMS (integer): The maximum amount of time to allow the query to
      *    run.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * writeConcern (MongoDB\Driver\WriteConcern): Write concern.
      *
      *    This is not supported for server versions < 3.4 and will result in an
@@ -98,6 +103,10 @@ class CreateIndexes implements Executable
             throw InvalidArgumentException::invalidType('"maxTimeMS" option', $options['maxTimeMS'], 'integer');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['writeConcern']) && ! $options['writeConcern'] instanceof WriteConcern) {
             throw InvalidArgumentException::invalidType('"writeConcern" option', $options['writeConcern'], 'MongoDB\Driver\WriteConcern');
         }
@@ -145,6 +154,10 @@ class CreateIndexes implements Executable
     {
         $options = [];
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         if (isset($this->options['writeConcern'])) {
             $options['writeConcern'] = $this->options['writeConcern'];
         }

src/Operation/DatabaseCommand.php

@@ -21,6 +21,7 @@ use MongoDB\Driver\Command;
 use MongoDB\Driver\Cursor;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Exception\InvalidArgumentException;
 
 /**
@@ -46,6 +47,10 @@ class DatabaseCommand implements Executable
      *    the wire protocol accordingly or adds the read preference to the
      *    command document, respectively.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * typeMap (array): Type map for BSON deserialization. This will be
      *    applied to the returned Cursor (it is not sent to the server).
      *
@@ -64,6 +69,10 @@ class DatabaseCommand implements Executable
             throw InvalidArgumentException::invalidType('"readPreference" option', $options['readPreference'], 'MongoDB\Driver\ReadPreference');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['typeMap']) && ! is_array($options['typeMap'])) {
             throw InvalidArgumentException::invalidType('"typeMap" option', $options['typeMap'], 'array');
         }
@@ -82,9 +91,7 @@ class DatabaseCommand implements Executable
      */
     public function execute(Server $server)
     {
-        $readPreference = isset($this->options['readPreference']) ? $this->options['readPreference'] : null;
-
-        $cursor = $server->executeCommand($this->databaseName, $this->command, $readPreference);
+        $cursor = $server->executeCommand($this->databaseName, $this->command, $this->createOptions());
 
         if (isset($this->options['typeMap'])) {
             $cursor->setTypeMap($this->options['typeMap']);
@@ -92,4 +99,25 @@ class DatabaseCommand implements Executable
 
         return $cursor;
     }
+
+    /**
+     * Create options for executing the command.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executecommand.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['readPreference'])) {
+            $options['readPreference'] = $this->options['readPreference'];
+        }
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        return $options;
+    }
 }

src/Operation/Delete.php

@@ -20,6 +20,7 @@ namespace MongoDB\Operation;
 use MongoDB\DeleteResult;
 use MongoDB\Driver\BulkWrite as Bulk;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -54,6 +55,10 @@ class Delete implements Executable
      *    This is not supported for server versions < 3.4 and will result in an
      *    exception at execution time if used.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * writeConcern (MongoDB\Driver\WriteConcern): Write concern.
      *
      * @param string       $databaseName   Database name
@@ -79,6 +84,10 @@ class Delete implements Executable
             throw InvalidArgumentException::invalidType('"collation" option', $options['collation'], 'array or object');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['writeConcern']) && ! $options['writeConcern'] instanceof WriteConcern) {
             throw InvalidArgumentException::invalidType('"writeConcern" option', $options['writeConcern'], 'MongoDB\Driver\WriteConcern');
         }
@@ -117,9 +126,29 @@ class Delete implements Executable
         $bulk = new Bulk();
         $bulk->delete($this->filter, $deleteOptions);
 
-        $writeConcern = isset($this->options['writeConcern']) ? $this->options['writeConcern'] : null;
-        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $writeConcern);
+        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $this->createOptions());
 
         return new DeleteResult($writeResult);
     }
+
+    /**
+     * Create options for executing the bulk write.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executebulkwrite.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        if (isset($this->options['writeConcern'])) {
+            $options['writeConcern'] = $this->options['writeConcern'];
+        }
+
+        return $options;
+    }
 }

src/Operation/DeleteMany.php

@@ -44,6 +44,10 @@ class DeleteMany implements Executable
      *    This is not supported for server versions < 3.4 and will result in an
      *    exception at execution time if used.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * writeConcern (MongoDB\Driver\WriteConcern): Write concern.
      *
      * @param string       $databaseName   Database name

src/Operation/DeleteOne.php

@@ -44,6 +44,10 @@ class DeleteOne implements Executable
      *    This is not supported for server versions < 3.4 and will result in an
      *    exception at execution time if used.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * writeConcern (MongoDB\Driver\WriteConcern): Write concern.
      *
      * @param string       $databaseName   Database name

src/Operation/Distinct.php

@@ -21,6 +21,7 @@ use MongoDB\Driver\Command;
 use MongoDB\Driver\ReadConcern;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
 use MongoDB\Exception\UnexpectedValueException;
@@ -64,6 +65,10 @@ class Distinct implements Executable
      *
      *  * readPreference (MongoDB\Driver\ReadPreference): Read preference.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      * @param string       $databaseName   Database name
      * @param string       $collectionName Collection name
      * @param string       $fieldName      Field for which to return distinct values
@@ -93,6 +98,10 @@ class Distinct implements Executable
             throw InvalidArgumentException::invalidType('"readPreference" option', $options['readPreference'], 'MongoDB\Driver\ReadPreference');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['readConcern']) && $options['readConcern']->isDefault()) {
             unset($options['readConcern']);
         }
@@ -179,6 +188,10 @@ class Distinct implements Executable
             $options['readPreference'] = $this->options['readPreference'];
         }
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         return $options;
     }
 }

src/Operation/DropCollection.php

@@ -19,6 +19,7 @@ namespace MongoDB\Operation;
 
 use MongoDB\Driver\Command;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -46,6 +47,10 @@ class DropCollection implements Executable
      *
      * Supported options:
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * typeMap (array): Type map for BSON deserialization. This will be used
      *    for the returned command result document.
      *
@@ -61,6 +66,10 @@ class DropCollection implements Executable
      */
     public function __construct($databaseName, $collectionName, array $options = [])
     {
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['typeMap']) && ! is_array($options['typeMap'])) {
             throw InvalidArgumentException::invalidType('"typeMap" option', $options['typeMap'], 'array');
         }
@@ -126,6 +135,10 @@ class DropCollection implements Executable
     {
         $options = [];
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         if (isset($this->options['writeConcern'])) {
             $options['writeConcern'] = $this->options['writeConcern'];
         }

src/Operation/DropDatabase.php

@@ -19,6 +19,7 @@ namespace MongoDB\Operation;
 
 use MongoDB\Driver\Command;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -44,6 +45,10 @@ class DropDatabase implements Executable
      *
      * Supported options:
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * typeMap (array): Type map for BSON deserialization. This will be used
      *    for the returned command result document.
      *
@@ -58,6 +63,10 @@ class DropDatabase implements Executable
      */
     public function __construct($databaseName, array $options = [])
     {
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['typeMap']) && ! is_array($options['typeMap'])) {
             throw InvalidArgumentException::invalidType('"typeMap" option', $options['typeMap'], 'array');
         }
@@ -109,6 +118,10 @@ class DropDatabase implements Executable
     {
         $options = [];
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         if (isset($this->options['writeConcern'])) {
             $options['writeConcern'] = $this->options['writeConcern'];
         }

src/Operation/DropIndexes.php

@@ -19,6 +19,7 @@ namespace MongoDB\Operation;
 
 use MongoDB\Driver\Command;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -48,6 +49,10 @@ class DropIndexes implements Executable
      *  * maxTimeMS (integer): The maximum amount of time to allow the query to
      *    run.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * typeMap (array): Type map for BSON deserialization. This will be used
      *    for the returned command result document.
      *
@@ -74,6 +79,10 @@ class DropIndexes implements Executable
             throw InvalidArgumentException::invalidType('"maxTimeMS" option', $options['maxTimeMS'], 'integer');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['typeMap']) && ! is_array($options['typeMap'])) {
             throw InvalidArgumentException::invalidType('"typeMap" option', $options['typeMap'], 'array');
         }
@@ -145,6 +154,10 @@ class DropIndexes implements Executable
     {
         $options = [];
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         if (isset($this->options['writeConcern'])) {
             $options['writeConcern'] = $this->options['writeConcern'];
         }

src/Operation/Find.php

@@ -22,6 +22,7 @@ use MongoDB\Driver\Query;
 use MongoDB\Driver\ReadConcern;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
 use MongoDB\Exception\UnsupportedException;
@@ -114,6 +115,10 @@ class Find implements Executable
      *  * returnKey (boolean): If true, returns only the index keys in the
      *    resulting documents.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * showRecordId (boolean): Determines whether to return the record
      *    identifier for each document. If true, adds a field $recordId to the
      *    returned documents.
@@ -226,6 +231,10 @@ class Find implements Executable
             throw InvalidArgumentException::invalidType('"returnKey" option', $options['returnKey'], 'boolean');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['showRecordId']) && ! is_bool($options['showRecordId'])) {
             throw InvalidArgumentException::invalidType('"showRecordId" option', $options['showRecordId'], 'boolean');
         }
@@ -275,9 +284,7 @@ class Find implements Executable
             throw UnsupportedException::readConcernNotSupported();
         }
 
-        $readPreference = isset($this->options['readPreference']) ? $this->options['readPreference'] : null;
-
-        $cursor = $server->executeQuery($this->databaseName . '.' . $this->collectionName, $this->createQuery(), $readPreference);
+        $cursor = $server->executeQuery($this->databaseName . '.' . $this->collectionName, $this->createQuery(), $this->createOptions());
 
         if (isset($this->options['typeMap'])) {
             $cursor->setTypeMap($this->options['typeMap']);
@@ -286,6 +293,27 @@ class Find implements Executable
         return $cursor;
     }
 
+    /**
+     * Create options for executing the command.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executequery.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['readPreference'])) {
+            $options['readPreference'] = $this->options['readPreference'];
+        }
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        return $options;
+    }
+
     /**
      * Create the find query.
      *

src/Operation/FindAndModify.php

@@ -19,6 +19,7 @@ namespace MongoDB\Operation;
 
 use MongoDB\Driver\Command;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -82,6 +83,10 @@ class FindAndModify implements Executable
      *  * remove (boolean): When true, removes the matched document. This option
      *    cannot be true if the update option is set. The default is false.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * sort (document): Determines which document the operation modifies if
      *    the query selects multiple documents.
      *
@@ -144,6 +149,10 @@ class FindAndModify implements Executable
             throw InvalidArgumentException::invalidType('"remove" option', $options['remove'], 'boolean');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['sort']) && ! is_array($options['sort']) && ! is_object($options['sort'])) {
             throw InvalidArgumentException::invalidType('"sort" option', $options['sort'], 'array or object');
         }
@@ -278,6 +287,10 @@ class FindAndModify implements Executable
     {
         $options = [];
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         if (isset($this->options['writeConcern'])) {
             $options['writeConcern'] = $this->options['writeConcern'];
         }

src/Operation/FindOne.php

@@ -78,6 +78,10 @@ class FindOne implements Executable
      *  * returnKey (boolean): If true, returns only the index keys in the
      *    resulting documents.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * showRecordId (boolean): Determines whether to return the record
      *    identifier for each document. If true, adds a field $recordId to the
      *    returned documents.

src/Operation/FindOneAndDelete.php

@@ -49,6 +49,10 @@ class FindOneAndDelete implements Executable
      *  * projection (document): Limits the fields to return for the matching
      *    document.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * sort (document): Determines which document the operation modifies if
      *    the query selects multiple documents.
      *

src/Operation/FindOneAndReplace.php

@@ -64,6 +64,10 @@ class FindOneAndReplace implements Executable
      *    FindOneAndReplace::RETURN_DOCUMENT_AFTER. The default is
      *    FindOneAndReplace::RETURN_DOCUMENT_BEFORE.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * sort (document): Determines which document the operation modifies if
      *    the query selects multiple documents.
      *

src/Operation/FindOneAndUpdate.php

@@ -67,6 +67,10 @@ class FindOneAndUpdate implements Executable
      *    FindOneAndUpdate::RETURN_DOCUMENT_AFTER. The default is
      *    FindOneAndUpdate::RETURN_DOCUMENT_BEFORE.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * sort (document): Determines which document the operation modifies if
      *    the query selects multiple documents.
      *

src/Operation/InsertMany.php

@@ -20,6 +20,7 @@ namespace MongoDB\Operation;
 use MongoDB\InsertManyResult;
 use MongoDB\Driver\BulkWrite as Bulk;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -55,6 +56,10 @@ class InsertMany implements Executable
      *    performing the remaining writes. If false, when a write fails,
      *    continue with the remaining writes, if any. The default is true.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * writeConcern (MongoDB\Driver\WriteConcern): Write concern.
      *
      * @param string           $databaseName   Database name
@@ -93,6 +98,10 @@ class InsertMany implements Executable
             throw InvalidArgumentException::invalidType('"ordered" option', $options['ordered'], 'boolean');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['writeConcern']) && ! $options['writeConcern'] instanceof WriteConcern) {
             throw InvalidArgumentException::invalidType('"writeConcern" option', $options['writeConcern'], 'MongoDB\Driver\WriteConcern');
         }
@@ -130,9 +139,29 @@ class InsertMany implements Executable
             $insertedIds[$i] = $bulk->insert($document);
         }
 
-        $writeConcern = isset($this->options['writeConcern']) ? $this->options['writeConcern'] : null;
-        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $writeConcern);
+        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $this->createOptions());
 
         return new InsertManyResult($writeResult, $insertedIds);
     }
+
+    /**
+     * Create options for executing the bulk write.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executebulkwrite.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        if (isset($this->options['writeConcern'])) {
+            $options['writeConcern'] = $this->options['writeConcern'];
+        }
+
+        return $options;
+    }
 }

src/Operation/InsertOne.php

@@ -20,6 +20,7 @@ namespace MongoDB\Operation;
 use MongoDB\InsertOneResult;
 use MongoDB\Driver\BulkWrite as Bulk;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -51,6 +52,10 @@ class InsertOne implements Executable
      *    For servers < 3.2, this option is ignored as document level validation
      *    is not available.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * writeConcern (MongoDB\Driver\WriteConcern): Write concern.
      *
      * @param string       $databaseName   Database name
@@ -69,6 +74,10 @@ class InsertOne implements Executable
             throw InvalidArgumentException::invalidType('"bypassDocumentValidation" option', $options['bypassDocumentValidation'], 'boolean');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['writeConcern']) && ! $options['writeConcern'] instanceof WriteConcern) {
             throw InvalidArgumentException::invalidType('"writeConcern" option', $options['writeConcern'], 'MongoDB\Driver\WriteConcern');
         }
@@ -102,9 +111,29 @@ class InsertOne implements Executable
         $bulk = new Bulk($options);
         $insertedId = $bulk->insert($this->document);
 
-        $writeConcern = isset($this->options['writeConcern']) ? $this->options['writeConcern'] : null;
-        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $writeConcern);
+        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $this->createOptions());
 
         return new InsertOneResult($writeResult, $insertedId);
     }
+
+    /**
+     * Create options for executing the bulk write.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executebulkwrite.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        if (isset($this->options['writeConcern'])) {
+            $options['writeConcern'] = $this->options['writeConcern'];
+        }
+
+        return $options;
+    }
 }

src/Operation/ListCollections.php

@@ -20,6 +20,7 @@ namespace MongoDB\Operation;
 use MongoDB\Driver\Command;
 use MongoDB\Driver\Query;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
 use MongoDB\Model\CachingIterator;
@@ -51,6 +52,10 @@ class ListCollections implements Executable
      *  * maxTimeMS (integer): The maximum amount of time to allow the query to
      *    run.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      * @param string $databaseName Database name
      * @param array  $options      Command options
      * @throws InvalidArgumentException for parameter/option parsing errors
@@ -65,6 +70,10 @@ class ListCollections implements Executable
             throw InvalidArgumentException::invalidType('"maxTimeMS" option', $options['maxTimeMS'], 'integer');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         $this->databaseName = (string) $databaseName;
         $this->options = $options;
     }
@@ -85,6 +94,26 @@ class ListCollections implements Executable
             : $this->executeLegacy($server);
     }
 
+    /**
+     * Create options for executing the command.
+     *
+     * Note: read preference is intentionally omitted, as the spec requires that
+     * the command be executed on the primary.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executecommand.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        return $options;
+    }
+
     /**
      * Returns information for all collections in this database using the
      * listCollections command.
@@ -105,7 +134,7 @@ class ListCollections implements Executable
             $cmd['maxTimeMS'] = $this->options['maxTimeMS'];
         }
 
-        $cursor = $server->executeCommand($this->databaseName, new Command($cmd));
+        $cursor = $server->executeCommand($this->databaseName, new Command($cmd), $this->createOptions());
         $cursor->setTypeMap(['root' => 'array', 'document' => 'array']);
 
         return new CollectionInfoCommandIterator(new CachingIterator($cursor));

src/Operation/ListDatabases.php

@@ -19,6 +19,7 @@ namespace MongoDB\Operation;
 
 use MongoDB\Driver\Command;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
 use MongoDB\Exception\UnexpectedValueException;
@@ -44,6 +45,10 @@ class ListDatabases implements Executable
      *  * maxTimeMS (integer): The maximum amount of time to allow the query to
      *    run.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      * @param array $options Command options
      * @throws InvalidArgumentException for parameter/option parsing errors
      */
@@ -53,6 +58,10 @@ class ListDatabases implements Executable
             throw InvalidArgumentException::invalidType('"maxTimeMS" option', $options['maxTimeMS'], 'integer');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         $this->options = $options;
     }
 
@@ -73,7 +82,7 @@ class ListDatabases implements Executable
             $cmd['maxTimeMS'] = $this->options['maxTimeMS'];
         }
 
-        $cursor = $server->executeCommand('admin', new Command($cmd));
+        $cursor = $server->executeCommand('admin', new Command($cmd), $this->createOptions());
         $cursor->setTypeMap(['root' => 'array', 'document' => 'array']);
         $result = current($cursor->toArray());
 
@@ -89,4 +98,24 @@ class ListDatabases implements Executable
          */
         return new DatabaseInfoLegacyIterator($result['databases']);
     }
+
+    /**
+     * Create options for executing the command.
+     *
+     * Note: read preference is intentionally omitted, as the spec requires that
+     * the command be executed on the primary.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executecommand.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        return $options;
+    }
 }

src/Operation/ListIndexes.php

@@ -20,6 +20,7 @@ namespace MongoDB\Operation;
 use MongoDB\Driver\Command;
 use MongoDB\Driver\Query;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
 use MongoDB\Model\CachingIterator;
@@ -52,6 +53,10 @@ class ListIndexes implements Executable
      *  * maxTimeMS (integer): The maximum amount of time to allow the query to
      *    run.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      * @param string $databaseName   Database name
      * @param string $collectionName Collection name
      * @param array  $options        Command options
@@ -63,6 +68,10 @@ class ListIndexes implements Executable
             throw InvalidArgumentException::invalidType('"maxTimeMS" option', $options['maxTimeMS'], 'integer');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         $this->databaseName = (string) $databaseName;
         $this->collectionName = (string) $collectionName;
         $this->options = $options;
@@ -83,6 +92,26 @@ class ListIndexes implements Executable
             : $this->executeLegacy($server);
     }
 
+    /**
+     * Create options for executing the command.
+     *
+     * Note: read preference is intentionally omitted, as the spec requires that
+     * the command be executed on the primary.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executecommand.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        return $options;
+    }
+
     /**
      * Returns information for all indexes for this collection using the
      * listIndexes command.
@@ -100,7 +129,7 @@ class ListIndexes implements Executable
         }
 
         try {
-            $cursor = $server->executeCommand($this->databaseName, new Command($cmd));
+            $cursor = $server->executeCommand($this->databaseName, new Command($cmd), $this->createOptions());
         } catch (DriverRuntimeException $e) {
             /* The server may return an error if the collection does not exist.
              * Check for possible error codes (see: SERVER-20463) and return an

src/Operation/MapReduce.php

@@ -22,6 +22,7 @@ use MongoDB\Driver\Command;
 use MongoDB\Driver\ReadConcern;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -112,6 +113,10 @@ class MapReduce implements Executable
      *  * scope (document): Specifies global variables that are accessible in
      *    the map, reduce and finalize functions.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * sort (document): Sorts the input documents. This option is useful for
      *    optimization. For example, specify the sort key to be the same as the
      *    emit key so that there are fewer reduce operations. The sort key must
@@ -183,6 +188,10 @@ class MapReduce implements Executable
             throw InvalidArgumentException::invalidType('"scope" option', $options['scope'], 'array or object');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if (isset($options['sort']) && ! is_array($options['sort']) && ! is_object($options['sort'])) {
             throw InvalidArgumentException::invalidType('"sort" option', $options['sort'], 'array or object');
         }
@@ -347,6 +356,10 @@ class MapReduce implements Executable
             $options['readPreference'] = $this->options['readPreference'];
         }
 
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
         if ($hasOutputCollection && isset($this->options['writeConcern'])) {
             $options['writeConcern'] = $this->options['writeConcern'];
         }

src/Operation/ReplaceOne.php

@@ -50,6 +50,10 @@ class ReplaceOne implements Executable
      *    This is not supported for server versions < 3.4 and will result in an
      *    exception at execution time if used.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * upsert (boolean): When true, a new document is created if no document
      *    matches the query. The default is false.
      *

src/Operation/Update.php

@@ -20,6 +20,7 @@ namespace MongoDB\Operation;
 use MongoDB\UpdateResult;
 use MongoDB\Driver\BulkWrite as Bulk;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
@@ -72,6 +73,10 @@ class Update implements Executable
      *    This option cannot be true if the $update argument is a replacement
      *    document (i.e. contains no update operators). The default is false.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * upsert (boolean): When true, a new document is created if no document
      *    matches the query. The default is false.
      *
@@ -120,6 +125,10 @@ class Update implements Executable
             throw new InvalidArgumentException('"multi" option cannot be true if $update is a replacement document');
         }
 
+        if (isset($options['session']) && ! $options['session'] instanceof Session) {
+            throw InvalidArgumentException::invalidType('"session" option', $options['session'], 'MongoDB\Driver\Session');
+        }
+
         if ( ! is_bool($options['upsert'])) {
             throw InvalidArgumentException::invalidType('"upsert" option', $options['upsert'], 'boolean');
         }
@@ -180,9 +189,29 @@ class Update implements Executable
         $bulk = new Bulk($bulkOptions);
         $bulk->update($this->filter, $this->update, $updateOptions);
 
-        $writeConcern = isset($this->options['writeConcern']) ? $this->options['writeConcern'] : null;
-        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $writeConcern);
+        $writeResult = $server->executeBulkWrite($this->databaseName . '.' . $this->collectionName, $bulk, $this->createOptions());
 
         return new UpdateResult($writeResult);
     }
+
+    /**
+     * Create options for executing the bulk write.
+     *
+     * @see http://php.net/manual/en/mongodb-driver-server.executebulkwrite.php
+     * @return array
+     */
+    private function createOptions()
+    {
+        $options = [];
+
+        if (isset($this->options['session'])) {
+            $options['session'] = $this->options['session'];
+        }
+
+        if (isset($this->options['writeConcern'])) {
+            $options['writeConcern'] = $this->options['writeConcern'];
+        }
+
+        return $options;
+    }
 }

src/Operation/UpdateMany.php

@@ -56,6 +56,10 @@ class UpdateMany implements Executable
      *    This is not supported for server versions < 3.4 and will result in an
      *    exception at execution time if used.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * upsert (boolean): When true, a new document is created if no document
      *    matches the query. The default is false.
      *

src/Operation/UpdateOne.php

@@ -56,6 +56,10 @@ class UpdateOne implements Executable
      *    This is not supported for server versions < 3.4 and will result in an
      *    exception at execution time if used.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * upsert (boolean): When true, a new document is created if no document
      *    matches the query. The default is false.
      *

src/Operation/Watch.php

@@ -23,6 +23,7 @@ use MongoDB\Driver\Manager;
 use MongoDB\Driver\ReadConcern;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\Server;
+use MongoDB\Driver\Session;
 use MongoDB\Driver\Exception\RuntimeException as DriverRuntimeException;
 use MongoDB\Exception\InvalidArgumentException;
 use MongoDB\Exception\UnexpectedValueException;
@@ -65,6 +66,10 @@ class Watch implements Executable
      *    Insert and replace operations always include the "fullDocument" field
      *    and delete operations omit the field as the document no longer exists.
      *
+     *  * session (MongoDB\Driver\Session): Client session.
+     *
+     *    Sessions are not supported for server versions < 3.6.
+     *
      *  * maxAwaitTimeMS (integer): The maximum amount of time for the server to
      *    wait on new documents to satisfy a change stream query.
      *

tests/Operation/AggregateFunctionalTest.php

@@ -72,6 +72,29 @@ class AggregateFunctionalTest extends FunctionalTestCase
         $operation->execute($this->getPrimaryServer());
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new Aggregate(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    [],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     /**
      * @dataProvider provideTypeMapOptionsAndExpectedDocuments
      */

tests/Operation/AggregateTest.php

@@ -64,6 +64,10 @@ class AggregateTest extends TestCase
             $options[][] = ['readPreference' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidArrayValues() as $value) {
             $options[][] = ['typeMap' => $value];
         }

tests/Operation/BulkWriteFunctionalTest.php

@@ -8,6 +8,8 @@ use MongoDB\Driver\BulkWrite as Bulk;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Model\BSONDocument;
 use MongoDB\Operation\BulkWrite;
+use MongoDB\Tests\CommandObserver;
+use stdClass;
 
 class BulkWriteFunctionalTest extends FunctionalTestCase
 {
@@ -286,6 +288,29 @@ class BulkWriteFunctionalTest extends FunctionalTestCase
         ]);
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new BulkWrite(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    [['insertOne' => [['_id' => 1]]]],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     /**
      * Create data fixtures.
      *

tests/Operation/BulkWriteTest.php

@@ -447,6 +447,10 @@ class BulkWriteTest extends TestCase
             $options[][] = ['ordered' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidWriteConcernValues() as $value) {
             $options[][] = ['writeConcern' => $value];
         }

tests/Operation/CountFunctionalTest.php

@@ -69,4 +69,27 @@ class CountFunctionalTest extends FunctionalTestCase
             $this->assertEquals(3, $operation->execute($this->getPrimaryServer()));
         }
     }
+
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new Count(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    [],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
 }

tests/Operation/CountTest.php

@@ -52,6 +52,10 @@ class CountTest extends TestCase
             $options[][] = ['readPreference' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidIntegerValues() as $value) {
             $options[][] = ['skip' => $value];
         }

tests/Operation/CreateCollectionFunctionalTest.php

@@ -25,4 +25,26 @@ class CreateCollectionFunctionalTest extends FunctionalTestCase
             }
         );
     }
+
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new CreateCollection(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
 }

tests/Operation/CreateCollectionTest.php

@@ -47,6 +47,10 @@ class CreateCollectionTest extends TestCase
             $options[][] = ['maxTimeMS' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidIntegerValues() as $value) {
             $options[][] = ['size' => $value];
         }

tests/Operation/CreateIndexesFunctionalTest.php

@@ -146,6 +146,29 @@ class CreateIndexesFunctionalTest extends FunctionalTestCase
         );
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new CreateIndexes(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    [['key' => ['x' => 1]]],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     /**
      * Asserts that an index with the given name exists for the collection.
      *

tests/Operation/CreateIndexesTest.php

@@ -32,6 +32,10 @@ class CreateIndexesTest extends TestCase
             $options[][] = ['maxTimeMS' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidWriteConcernValues() as $value) {
             $options[][] = ['writeConcern' => $value];
         }

tests/Operation/DatabaseCommandFunctionalTest.php

+<?php
+
+namespace MongoDB\Tests\Operation;
+
+use MongoDB\Operation\DatabaseCommand;
+use MongoDB\Tests\CommandObserver;
+use stdClass;
+
+class DatabaseCommandFunctionalTest extends FunctionalTestCase
+{
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new DatabaseCommand(
+                    $this->getDatabaseName(),
+                    ['ping' => 1],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+}

tests/Operation/DatabaseCommandTest.php

@@ -32,6 +32,10 @@ class DatabaseCommandTest extends TestCase
             $options[][] = ['readPreference' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidArrayValues() as $value) {
             $options[][] = ['typeMap' => $value];
         }

tests/Operation/DeleteFunctionalTest.php

@@ -7,6 +7,8 @@ use MongoDB\Collection;
 use MongoDB\Driver\BulkWrite;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Operation\Delete;
+use MongoDB\Tests\CommandObserver;
+use stdClass;
 
 class DeleteFunctionalTest extends FunctionalTestCase
 {
@@ -58,6 +60,30 @@ class DeleteFunctionalTest extends FunctionalTestCase
         $this->assertSameDocuments($expected, $this->collection->find());
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new Delete(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    [],
+                    0,
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     public function testUnacknowledgedWriteConcern()
     {
         $filter = ['_id' => 1];

tests/Operation/DeleteTest.php

@@ -47,6 +47,10 @@ class DeleteTest extends TestCase
             $options[][] = ['collation' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidWriteConcernValues() as $value) {
             $options[][] = ['writeConcern' => $value];
         }

tests/Operation/DistinctFunctionalTest.php

@@ -27,4 +27,28 @@ class DistinctFunctionalTest extends FunctionalTestCase
             }
         );
     }
+
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new Distinct(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    'x',
+                    [],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
 }

tests/Operation/DistinctTest.php

@@ -44,6 +44,10 @@ class DistinctTest extends TestCase
             $options[][] = ['readPreference' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         return $options;
     }
 }

tests/Operation/DropCollectionFunctionalTest.php

@@ -53,6 +53,28 @@ class DropCollectionFunctionalTest extends FunctionalTestCase
         $operation->execute($this->getPrimaryServer());
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new DropCollection(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     /**
      * Asserts that a collection with the given name does not exist on the
      * server.

tests/Operation/DropCollectionTest.php

@@ -19,6 +19,10 @@ class DropCollectionTest extends TestCase
     {
         $options = [];
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidArrayValues() as $value) {
             $options[][] = ['typeMap' => $value];
         }

tests/Operation/DropDatabaseFunctionalTest.php

@@ -58,6 +58,27 @@ class DropDatabaseFunctionalTest extends FunctionalTestCase
         $operation->execute($server);
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new DropDatabase(
+                    $this->getDatabaseName(),
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     /**
      * Asserts that a database with the given name does not exist on the server.
      *

tests/Operation/DropDatabaseTest.php

@@ -19,6 +19,10 @@ class DropDatabaseTest extends TestCase
     {
         $options = [];
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidArrayValues() as $value) {
             $options[][] = ['typeMap' => $value];
         }

tests/Operation/DropIndexesFunctionalTest.php

@@ -88,6 +88,32 @@ class DropIndexesFunctionalTest extends FunctionalTestCase
         }
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        $operation = new CreateIndexes($this->getDatabaseName(), $this->getCollectionName(), [['key' => ['x' => 1]]]);
+        $operation->execute($this->getPrimaryServer());
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new DropIndexes(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    '*',
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     /**
      * Asserts that an index with the given name exists for the collection.
      *

tests/Operation/DropIndexesTest.php

@@ -31,6 +31,10 @@ class DropIndexesTest extends TestCase
             $options[][] = ['maxTimeMS' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidArrayValues() as $value) {
             $options[][] = ['typeMap' => $value];
         }

tests/Operation/FindAndModifyFunctionalTest.php

@@ -28,6 +28,28 @@ class FindAndModifyFunctionalTest extends FunctionalTestCase
         );
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new FindAndModify(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    ['remove' => true, 'session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     /**
      * @dataProvider provideTypeMapOptionsAndExpectedDocument
      */

tests/Operation/FindAndModifyTest.php

@@ -51,6 +51,10 @@ class FindAndModifyTest extends TestCase
             $options[][] = ['remove' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidDocumentValues() as $value) {
             $options[][] = ['sort' => $value];
         }

tests/Operation/FindFunctionalTest.php

@@ -82,6 +82,29 @@ class FindFunctionalTest extends FunctionalTestCase
         }
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new Find(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    [],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     /**
      * @dataProvider provideTypeMapOptionsAndExpectedDocuments
      */

tests/Operation/FindTest.php

@@ -100,6 +100,10 @@ class FindTest extends TestCase
             $options[][] = ['returnKey' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidBooleanValues() as $value) {
             $options[][] = ['showRecordId' => $value];
         }

tests/Operation/FunctionalTestCase.php

@@ -41,4 +41,9 @@ abstract class FunctionalTestCase extends BaseFunctionalTestCase
     {
         return new WriteConcern(-2);
     }
+
+    protected function createSession()
+    {
+        return $this->manager->startSession();
+    }
 }

tests/Operation/InsertManyFunctionalTest.php

@@ -7,6 +7,8 @@ use MongoDB\InsertManyResult;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Model\BSONDocument;
 use MongoDB\Operation\InsertMany;
+use MongoDB\Tests\CommandObserver;
+use stdClass;
 
 class InsertManyFunctionalTest extends FunctionalTestCase
 {
@@ -50,6 +52,29 @@ class InsertManyFunctionalTest extends FunctionalTestCase
         $this->assertSameDocuments($expected, $this->collection->find());
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new InsertMany(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    [['_id' => 1], ['_id' => 2]],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     public function testUnacknowledgedWriteConcern()
     {
         $documents = [['x' => 11]];

tests/Operation/InsertManyTest.php

@@ -55,6 +55,10 @@ class InsertManyTest extends TestCase
             $options[][] = ['ordered' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidWriteConcernValues() as $value) {
             $options[][] = ['writeConcern' => $value];
         }

tests/Operation/InsertOneFunctionalTest.php

@@ -7,6 +7,8 @@ use MongoDB\InsertOneResult;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Model\BSONDocument;
 use MongoDB\Operation\InsertOne;
+use MongoDB\Tests\CommandObserver;
+use stdClass;
 
 class InsertOneFunctionalTest extends FunctionalTestCase
 {
@@ -65,6 +67,29 @@ class InsertOneFunctionalTest extends FunctionalTestCase
         $this->assertSameDocuments($expected, $this->collection->find());
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new InsertOne(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    ['_id' => 1],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     public function testUnacknowledgedWriteConcern()
     {
         $document = ['x' => 11];

tests/Operation/InsertOneTest.php

@@ -32,6 +32,10 @@ class InsertOneTest extends TestCase
             $options[][] = ['bypassDocumentValidation' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidWriteConcernValues() as $value) {
             $options[][] = ['writeConcern' => $value];
         }

tests/Operation/ListCollectionsFunctionalTest.php

@@ -5,6 +5,8 @@ namespace MongoDB\Tests\Operation;
 use MongoDB\Operation\DropDatabase;
 use MongoDB\Operation\InsertOne;
 use MongoDB\Operation\ListCollections;
+use MongoDB\Tests\CommandObserver;
+use stdClass;
 
 class ListCollectionsFunctionalTest extends FunctionalTestCase
 {
@@ -44,4 +46,25 @@ class ListCollectionsFunctionalTest extends FunctionalTestCase
 
         $this->assertCount(0, $collections);
     }
+
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new ListCollections(
+                    $this->getDatabaseName(),
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
 }

tests/Operation/ListCollectionsTest.php

@@ -27,6 +27,10 @@ class ListCollectionsTest extends TestCase
             $options[][] = ['maxTimeMS' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         return $options;
     }
 }

tests/Operation/ListDatabasesFunctionalTest.php

+<?php
+
+namespace MongoDB\Tests\Operation;
+
+use MongoDB\Operation\ListDatabases;
+use MongoDB\Tests\CommandObserver;
+use stdClass;
+
+class ListDatabasesFunctionalTest extends FunctionalTestCase
+{
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new ListDatabases(
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+}

tests/Operation/ListDatabasesTest.php

@@ -23,6 +23,10 @@ class ListDatabasesTest extends TestCase
             $options[][] = ['maxTimeMS' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         return $options;
     }
 }

tests/Operation/ListIndexesFunctionalTest.php

@@ -5,6 +5,8 @@ namespace MongoDB\Tests\Operation;
 use MongoDB\Operation\DropCollection;
 use MongoDB\Operation\InsertOne;
 use MongoDB\Operation\ListIndexes;
+use MongoDB\Tests\CommandObserver;
+use stdClass;
 
 class ListIndexesFunctionalTest extends FunctionalTestCase
 {
@@ -40,4 +42,26 @@ class ListIndexesFunctionalTest extends FunctionalTestCase
 
         $this->assertCount(0, $indexes);
     }
+
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new ListIndexes(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
 }

tests/Operation/ListIndexesTest.php

@@ -23,6 +23,10 @@ class ListIndexesTest extends TestCase
             $options[][] = ['maxTimeMS' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         return $options;
     }
 }

tests/Operation/MapReduceFunctionalTest.php

@@ -129,6 +129,33 @@ class MapReduceFunctionalTest extends FunctionalTestCase
         $this->assertEmpty($result->getTiming());
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        $this->createFixtures(3);
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new MapReduce(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    new Javascript('function() { emit(this.x, this.y); }'),
+                    new Javascript('function(key, values) { return Array.sum(values); }'),
+                    ['inline' => 1],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     /**
      * @dataProvider provideTypeMapOptionsAndExpectedDocuments
      */

tests/Operation/MapReduceTest.php

@@ -83,6 +83,10 @@ class MapReduceTest extends TestCase
             $options[][] = ['scope' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidDocumentValues() as $value) {
             $options[][] = ['sort' => $value];
         }

tests/Operation/UpdateFunctionalTest.php

@@ -7,6 +7,8 @@ use MongoDB\UpdateResult;
 use MongoDB\Driver\BulkWrite;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Operation\Update;
+use MongoDB\Tests\CommandObserver;
+use stdClass;
 
 class UpdateFunctionalTest extends FunctionalTestCase
 {
@@ -19,6 +21,30 @@ class UpdateFunctionalTest extends FunctionalTestCase
         $this->collection = new Collection($this->manager, $this->getDatabaseName(), $this->getCollectionName());
     }
 
+    public function testSessionOption()
+    {
+        if (version_compare($this->getServerVersion(), '3.6.0', '<')) {
+            $this->markTestSkipped('Sessions are not supported');
+        }
+
+        (new CommandObserver)->observe(
+            function() {
+                $operation = new Update(
+                    $this->getDatabaseName(),
+                    $this->getCollectionName(),
+                    ['_id' => 1],
+                    ['$inc' => ['x' => 1]],
+                    ['session' => $this->createSession()]
+                );
+
+                $operation->execute($this->getPrimaryServer());
+            },
+            function(stdClass $command) {
+                $this->assertObjectHasAttribute('lsid', $command);
+            }
+        );
+    }
+
     public function testUpdateOne()
     {
         $this->createFixtures(3);

tests/Operation/UpdateTest.php

@@ -55,6 +55,10 @@ class UpdateTest extends TestCase
             $options[][] = ['multi' => $value];
         }
 
+        foreach ($this->getInvalidSessionValues() as $value) {
+            $options[][] = ['session' => $value];
+        }
+
         foreach ($this->getInvalidBooleanValues() as $value) {
             $options[][] = ['upsert' => $value];
         }

tests/TestCase.php

@@ -103,6 +103,16 @@ abstract class TestCase extends BaseTestCase
         return [123, 3.14, 'foo', true, [], new stdClass, new ReadConcern, new WriteConcern(1)];
     }
 
+    /**
+     * Return a list of invalid Session values.
+     *
+     * @return array
+     */
+    protected function getInvalidSessionValues()
+    {
+        return [123, 3.14, 'foo', true, [], new stdClass, new ReadConcern, new ReadPreference(ReadPreference::RP_PRIMARY), new WriteConcern(1)];
+    }
+
     /**
      * Return a list of invalid string values.
      *