public function testReadPreference()
{
$client = $this->getClient();
$this->assertSame(['type' => \MongoClient::RP_PRIMARY], $client->getReadPreference());
$this->assertTrue($client->setReadPreference(\MongoClient::RP_SECONDARY, [['a' => 'b']]));
$this->assertSame(['type' => \MongoClient::RP_SECONDARY, 'tagsets' => [['a' => 'b']]], $client->getReadPreference());
}