add executeCommand method to Database

Author: tuyakhov

.gitignore

@@ -7,3 +7,4 @@ php.ini
 phpunit.xml
 apigen.phar
 site
+.idea

src/Database.php

@@ -135,6 +135,19 @@ public function dropCollection($collectionName)
         return $operation->execute($server);
     }
 
+    /**
+     * This is the method to issue database commands.
+     *
+     * @param Command $command A database command to send
+     * @param ReadPreference|null $readPreference Default read preference to apply
+     * @return Cursor
+     */
+    public function executeCommand(Command $command, ReadPreference $readPreference = null)
+    {
+        $server = $this->manager->selectServer(new ReadPreference(ReadPreference::RP_PRIMARY));
+        return $server->executeCommand($this->databaseName, $command, $readPreference);
+    }
+
     /**
      * Returns the database name.
      *

tests/Database/DatabaseFunctionalTest.php

@@ -6,6 +6,7 @@
 use MongoDB\Driver\BulkWrite;
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\WriteConcern;
+use MongoDB\Driver\Command;
 
 /**
  * Functional tests for the Database class.
@@ -77,6 +78,19 @@ public function testDrop()
         $this->assertCollectionCount($this->getNamespace(), 0);
     }
 
+    public function testCommand()
+    {
+        $command = new Command(['isMaster' => 1]);
+        $readPreference = new ReadPreference(ReadPreference::RP_PRIMARY);
+        $cursor = $this->database->executeCommand($command, $readPreference);
+        $this->assertInstanceOf('MongoDB\Driver\Cursor', $cursor);
+        $cursor->setTypeMap(['root' => 'array', 'document' => 'array']);
+        $document = current($cursor->toArray());
+        $this->assertCommandSucceeded($document);
+        $this->assertArrayHasKey('ismaster', $document);
+        $this->assertTrue($document['ismaster']);
+    }
+
     public function testSelectCollectionInheritsReadPreferenceAndWriteConcern()
     {
         $databaseOptions = [

tests/Database/FunctionalTestCase.php

@@ -10,6 +10,9 @@
  */
 abstract class FunctionalTestCase extends BaseFunctionalTestCase
 {
+    /**
+     * @var $database Database
+     */
     protected $database;
 
     public function setUp()