predis/tests/Predis/Connection/Aggregate/MasterSlaveReplicationTest.php

<?php

/*
 * This file is part of the Predis package.
 *
 * (c) Daniele Alessandri <suppakilla@gmail.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Predis\Connection\Aggregate;

use Predis\Connection;
use Predis\Profile;
use Predis\Replication\ReplicationStrategy;
use PredisTestCase;

/**
 *
 */
class MasterSlaveReplicationTest extends PredisTestCase
{
    /**
     * @group disconnected
     */
    public function testAddingConnectionsToReplication()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave2 = $this->getMockConnection('tcp://host3?alias=slave2');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);
        $replication->add($slave2);

        $this->assertSame($master, $replication->getConnectionById('master'));
        $this->assertSame($slave1, $replication->getConnectionById('slave1'));
        $this->assertSame($slave2, $replication->getConnectionById('slave2'));

        $this->assertSame($master, $replication->getMaster());
        $this->assertSame(array($slave1, $slave2), $replication->getSlaves());
    }

    /**
     * @group disconnected
     */
    public function testRemovingConnectionsFromReplication()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave2 = $this->getMockConnection('tcp://host3?alias=slave2');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $this->assertTrue($replication->remove($slave1));
        $this->assertFalse($replication->remove($slave2));

        $this->assertSame($master, $replication->getMaster());
        $this->assertSame(array(), $replication->getSlaves());
    }

    /**
     * @group disconnected
     * @expectedException \Predis\ClientException
     * @expectedExceptionMessage No available connection for replication
     */
    public function testThrowsExceptionOnEmptyReplication()
    {
        $replication = new MasterSlaveReplication();
        $replication->connect();
    }

    /**
     * @group disconnected
     */
    public function testConnectsToOneOfSlaves()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->never())->method('connect');

        $slave = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave->expects($this->once())->method('connect');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave);

        $replication->connect();
    }

    /**
     * @group disconnected
     */
    public function testConnectsToMasterOnMissingSlaves()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');

        $replication = new MasterSlaveReplication();
        $replication->add($master);

        $replication->connect();
        $this->assertSame($master, $replication->getCurrent());
    }

    /**
     * @group disconnected
     */
    public function testIsConnectedReturnsTrueIfAtLeastOneConnectionIsOpen()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->never())->method('isConnected')->will($this->returnValue(false));

        $slave = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave->expects($this->once())->method('isConnected')->will($this->returnValue(true));

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave);
        $replication->connect();

        $this->assertTrue($replication->isConnected());
    }

    /**
     * @group disconnected
     */
    public function testIsConnectedReturnsFalseIfAllConnectionsAreClosed()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->any())->method('isConnected')->will($this->returnValue(false));

        $slave = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave->expects($this->any())->method('isConnected')->will($this->returnValue(false));

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave);

        $this->assertFalse($replication->isConnected());

        $replication->connect();
        $replication->disconnect();

        $this->assertFalse($replication->isConnected());
    }

    /**
     * @group disconnected
     */
    public function testDisconnectForcesCurrentConnectionToDisconnect()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('disconnect');

        $slave = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave->expects($this->once())->method('disconnect');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave);

        $replication->disconnect();
    }

    /**
     * @group disconnected
     */
    public function testCanSwitchConnectionByAlias()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $this->assertNull($replication->getCurrent());

        $replication->switchTo('master');
        $this->assertSame($master, $replication->getCurrent());
        $replication->switchTo('slave1');
        $this->assertSame($slave1, $replication->getCurrent());
    }

    /**
     * @group disconnected
     * @expectedException \InvalidArgumentException
     * @expectedExceptionMessage Invalid connection or connection not found.
     */
    public function testThrowsErrorWhenSwitchingToUnknownConnectionByAlias()
    {
        $replication = new MasterSlaveReplication();
        $replication->add($this->getMockConnection('tcp://host1?alias=master'));
        $replication->add($this->getMockConnection('tcp://host2?alias=slave1'));

        $replication->switchTo('unknown');
    }

    /**
     * @group disconnected
     */
    public function testCanSwitchConnectionByInstance()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $this->assertNull($replication->getCurrent());

        $replication->switchTo($master);
        $this->assertSame($master, $replication->getCurrent());
        $replication->switchTo($slave1);
        $this->assertSame($slave1, $replication->getCurrent());
    }

    /**
     * @group disconnected
     * @expectedException \InvalidArgumentException
     * @expectedExceptionMessage Invalid connection or connection not found.
     */
    public function testThrowsErrorWhenSwitchingToUnknownConnectionByInstance()
    {
        $replication = new MasterSlaveReplication();
        $replication->add($this->getMockConnection('tcp://host1?alias=master'));
        $replication->add($this->getMockConnection('tcp://host2?alias=slave1'));

        $slave2 = $this->getMockConnection('tcp://host3?alias=slave2');

        $replication->switchTo($slave2);
    }

    /**
     * @group disconnected
     */
    public function testCanSwitchToMaster()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave2 = $this->getMockConnection('tcp://host3?alias=slave2');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);
        $replication->add($slave2);

        $this->assertNull($replication->getCurrent());

        $replication->switchToMaster();
        $this->assertSame($master, $replication->getCurrent());
    }

    /**
     * @group disconnected
     * @expectedException \InvalidArgumentException
     * @expectedExceptionMessage Invalid connection or connection not found.
     */
    public function testThrowsErrorOnSwitchToMasterWithNoMasterDefined()
    {
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');

        $replication = new MasterSlaveReplication();
        $replication->add($slave1);

        $replication->switchToMaster();
    }

    /**
     * @group disconnected
     * @todo We should find a way to test that the slave is indeed randomly selected.
     */
    public function testCanSwitchToRandomSlave()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $this->assertNull($replication->getCurrent());

        $replication->switchToSlave();
        $this->assertSame($slave1, $replication->getCurrent());
    }

    /**
     * @group disconnected
     * @expectedException \InvalidArgumentException
     * @expectedExceptionMessage Invalid connection or connection not found.
     */
    public function testThrowsErrorOnSwitchToRandomSlaveWithNoSlavesDefined()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');

        $replication = new MasterSlaveReplication();
        $replication->add($master);

        $replication->switchToSlave();
    }

    /**
     * @group disconnected
     */
    public function testUsesSlavesOnReadOnlyCommands()
    {
        $profile = Profile\Factory::getDefault();

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $cmd = $profile->createCommand('exists', array('foo'));
        $this->assertSame($slave1, $replication->getConnection($cmd));

        $cmd = $profile->createCommand('get', array('foo'));
        $this->assertSame($slave1, $replication->getConnection($cmd));
    }

    /**
     * @group disconnected
     */
    public function testUsesMasterOnWriteRequests()
    {
        $profile = Profile\Factory::getDefault();

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $cmd = $profile->createCommand('set', array('foo', 'bar'));
        $this->assertSame($master, $replication->getConnection($cmd));

        $cmd = $profile->createCommand('get', array('foo'));
        $this->assertSame($master, $replication->getConnection($cmd));
    }

    /**
     * @group disconnected
     */
    public function testUsesMasterOnReadRequestsWhenNoSlavesAvailable()
    {
        $profile = Profile\Factory::getDefault();

        $master = $this->getMockConnection('tcp://host1?alias=master');

        $replication = new MasterSlaveReplication();
        $replication->add($master);

        $cmd = $profile->createCommand('exists', array('foo'));
        $this->assertSame($master, $replication->getConnection($cmd));

        $cmd = $profile->createCommand('set', array('foo', 'bar'));
        $this->assertSame($master, $replication->getConnection($cmd));
    }

    /**
     * @group disconnected
     */
    public function testSwitchesFromSlaveToMasterOnWriteRequestss()
    {
        $profile = Profile\Factory::getDefault();

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $cmd = $profile->createCommand('exists', array('foo'));
        $this->assertSame($slave1, $replication->getConnection($cmd));

        $cmd = $profile->createCommand('set', array('foo', 'bar'));
        $this->assertSame($master, $replication->getConnection($cmd));

        $cmd = $profile->createCommand('exists', array('foo'));
        $this->assertSame($master, $replication->getConnection($cmd));
    }

    /**
     * @group disconnected
     */
    public function testWritesCommandToCorrectConnection()
    {
        $profile = Profile\Factory::getDefault();
        $cmdExists = $profile->createCommand('exists', array('foo'));
        $cmdSet = $profile->createCommand('set', array('foo', 'bar'));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('writeRequest')->with($cmdSet);

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->once())->method('writeRequest')->with($cmdExists);

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->writeRequest($cmdExists);
        $replication->writeRequest($cmdSet);
    }

    /**
     * @group disconnected
     */
    public function testReadsCommandFromCorrectConnection()
    {
        $profile = Profile\Factory::getDefault();
        $cmdExists = $profile->createCommand('exists', array('foo'));
        $cmdSet = $profile->createCommand('set', array('foo', 'bar'));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('readResponse')->with($cmdSet);

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->once())->method('readResponse')->with($cmdExists);

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->readResponse($cmdExists);
        $replication->readResponse($cmdSet);
    }

    /**
     * @group disconnected
     */
    public function testExecutesCommandOnCorrectConnection()
    {
        $profile = Profile\Factory::getDefault();
        $cmdExists = $profile->createCommand('exists', array('foo'));
        $cmdSet = $profile->createCommand('set', array('foo', 'bar'));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('executeCommand')->with($cmdSet);

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->once())->method('executeCommand')->with($cmdExists);

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->executeCommand($cmdExists);
        $replication->executeCommand($cmdSet);
    }

    /**
     * @group disconnected
     */
    public function testWatchTriggersSwitchToMasterConnection()
    {
        $profile = Profile\Factory::getDefault();
        $cmdWatch = $profile->createCommand('watch', array('foo'));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('executeCommand')->with($cmdWatch);

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->never())->method('executeCommand');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->executeCommand($cmdWatch);
    }

    /**
     * @group disconnected
     */
    public function testMultiTriggersSwitchToMasterConnection()
    {
        $profile = Profile\Factory::getDefault();
        $cmdMulti = $profile->createCommand('multi');

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('executeCommand')->with($cmdMulti);

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->never())->method('executeCommand');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->executeCommand($cmdMulti);
    }

    /**
     * @group disconnected
     */
    public function testEvalTriggersSwitchToMasterConnection()
    {
        $profile = Profile\Factory::get('dev');
        $cmdEval = $profile->createCommand('eval', array("return redis.call('info')"));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('executeCommand')->with($cmdEval);

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->never())->method('executeCommand');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->executeCommand($cmdEval);
    }

    /**
     * @group disconnected
     */
    public function testSortTriggersSwitchToMasterConnectionOnStoreModifier()
    {
        $profile = Profile\Factory::get('dev');
        $cmdSortNormal = $profile->createCommand('sort', array('key'));
        $cmdSortStore = $profile->createCommand('sort', array('key', array('store' => 'key:store')));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('executeCommand')->with($cmdSortStore);

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->once())->method('executeCommand')->with($cmdSortNormal);

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->executeCommand($cmdSortNormal);
        $replication->executeCommand($cmdSortStore);
    }

    /**
     * @group disconnected
     */
    public function testDiscardsUnreachableSlaveAndExecutesReadOnlyCommandOnNextSlave()
    {
        $profile = Profile\Factory::getDefault();
        $cmdExists = $profile->createCommand('exists', array('key'));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->never())->method('executeCommand');

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->once())
               ->method('executeCommand')
               ->with($cmdExists)
               ->will($this->throwException(new Connection\ConnectionException($slave1)));

        $slave2 = $this->getMockConnection('tcp://host3?alias=slave2');
        $slave2->expects($this->once())
               ->method('executeCommand')
               ->with($cmdExists)
               ->will($this->returnValue(1));

        $replication = new MasterSlaveReplication();

        $replication->add($master);
        $replication->add($slave1);
        $replication->add($slave2);

        $replication->switchTo($slave1);

        $response = $replication->executeCommand($cmdExists);

        $this->assertSame(1, $response);
        $this->assertNull($replication->getConnectionById('slave1'));
        $this->assertSame($slave2, $replication->getConnectionById('slave2'));
    }

    /**
     * @group disconnected
     */
    public function testDiscardsUnreachableSlavesAndExecutesReadOnlyCommandOnMaster()
    {
        $profile = Profile\Factory::getDefault();
        $cmdExists = $profile->createCommand('exists', array('key'));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())
               ->method('executeCommand')
               ->with($cmdExists)
               ->will($this->returnValue(1));

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->once())
               ->method('executeCommand')
               ->with($cmdExists)
               ->will($this->throwException(new Connection\ConnectionException($slave1)));

        $slave2 = $this->getMockConnection('tcp://host3?alias=slave2');
        $slave2->expects($this->once())
               ->method('executeCommand')
               ->with($cmdExists)
               ->will($this->throwException(new Connection\ConnectionException($slave2)));

        $replication = new MasterSlaveReplication();

        $replication->add($master);
        $replication->add($slave1);
        $replication->add($slave2);

        $replication->switchTo($slave1);

        $response = $replication->executeCommand($cmdExists);

        $this->assertSame(1, $response);
        $this->assertNull($replication->getConnectionById('slave1'));
        $this->assertNull($replication->getConnectionById('slave2'));
    }

    /**
     * @group disconnected
     */
    public function testSucceedOnReadOnlyCommandAndNoConnectionSetAsMaster()
    {
        $profile = Profile\Factory::getDefault();
        $cmdExists = $profile->createCommand('exists', array('key'));

        $slave1 = $this->getMockConnection('tcp://host1?alias=slave1');
        $slave1->expects($this->once())
               ->method('executeCommand')
               ->with($cmdExists)
               ->will($this->returnValue(1));

        $replication = new MasterSlaveReplication();
        $replication->add($slave1);

        $response = $replication->executeCommand($cmdExists);

        $this->assertSame(1, $response);
    }

    /**
     * @group disconnected
     * @expectedException \Predis\ClientException
     * @expectedMessage No master server available for replication
     */
    public function testFailsOnWriteCommandAndNoConnectionSetAsMaster()
    {
        $profile = Profile\Factory::getDefault();
        $cmdSet = $profile->createCommand('set', array('key', 'value'));

        $slave1 = $this->getMockConnection('tcp://host1?alias=slave1');
        $slave1->expects($this->never())->method('executeCommand');

        $replication = new MasterSlaveReplication();
        $replication->add($slave1);

        $replication->executeCommand($cmdSet);
    }

    /**
     * @group disconnected
     * @expectedException \Predis\Connection\ConnectionException
     */
    public function testFailsOnUnreachableMaster()
    {
        $profile = Profile\Factory::getDefault();
        $cmdSet = $profile->createCommand('set', array('key', 'value'));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())
               ->method('executeCommand')
               ->with($cmdSet)
               ->will($this->throwException(new Connection\ConnectionException($master)));

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->never())
               ->method('executeCommand');

        $replication = new MasterSlaveReplication();

        $replication->add($master);
        $replication->add($slave1);

        $replication->executeCommand($cmdSet);
    }

    /**
     * @group disconnected
     * @expectedException \Predis\NotSupportedException
     * @expectedExceptionMessage The command 'INFO' is not allowed in replication mode.
     */
    public function testThrowsExceptionOnNonSupportedCommand()
    {
        $cmd = Profile\Factory::getDefault()->createCommand('info');

        $replication = new MasterSlaveReplication();
        $replication->add($this->getMockConnection('tcp://host1?alias=master'));
        $replication->add($this->getMockConnection('tcp://host2?alias=slave1'));

        $replication->getConnection($cmd);
    }

    /**
     * @group disconnected
     */
    public function testCanOverrideReadOnlyFlagForCommands()
    {
        $profile = Profile\Factory::getDefault();
        $cmdSet = $profile->createCommand('set', array('foo', 'bar'));
        $cmdGet = $profile->createCommand('get', array('foo'));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('executeCommand')->with($cmdGet);

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->once())->method('executeCommand')->with($cmdSet);

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->getReplicationStrategy()->setCommandReadOnly($cmdSet->getId(), true);
        $replication->getReplicationStrategy()->setCommandReadOnly($cmdGet->getId(), false);

        $replication->executeCommand($cmdSet);
        $replication->executeCommand($cmdGet);
    }

    /**
     * @group disconnected
     */
    public function testAcceptsCallableToOverrideReadOnlyFlagForCommands()
    {
        $profile = Profile\Factory::getDefault();
        $cmdExistsFoo = $profile->createCommand('exists', array('foo'));
        $cmdExistsBar = $profile->createCommand('exists', array('bar'));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->once())->method('executeCommand')->with($cmdExistsBar);

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->once())->method('executeCommand')->with($cmdExistsFoo);

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->getReplicationStrategy()->setCommandReadOnly('exists', function ($cmd) {
            list($arg1) = $cmd->getArguments();

            return $arg1 === 'foo';
        });

        $replication->executeCommand($cmdExistsFoo);
        $replication->executeCommand($cmdExistsBar);
    }

    /**
     * @group disconnected
     */
    public function testCanSetReadOnlyFlagForEvalScripts()
    {
        $profile = Profile\Factory::get('dev');

        $cmdEval = $profile->createCommand('eval', array($script = "return redis.call('info');"));
        $cmdEvalSha = $profile->createCommand('evalsha', array($scriptSHA1 = sha1($script)));

        $master = $this->getMockConnection('tcp://host1?alias=master');
        $master->expects($this->never())->method('executeCommand');

        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');
        $slave1->expects($this->exactly(2))
               ->method('executeCommand')
               ->with($this->logicalOr($cmdEval, $cmdEvalSha));

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $replication->getReplicationStrategy()->setScriptReadOnly($script);

        $replication->executeCommand($cmdEval);
        $replication->executeCommand($cmdEvalSha);
    }

    /**
     * @group disconnected
     */
    public function testExposesReplicationStrategy()
    {
        $replication = new MasterSlaveReplication();
        $this->assertInstanceOf('Predis\Replication\ReplicationStrategy', $replication->getReplicationStrategy());

        $strategy = new ReplicationStrategy();
        $replication = new MasterSlaveReplication($strategy);
        $this->assertSame($strategy, $replication->getReplicationStrategy());
    }

    /**
     * @group disconnected
     */
    public function testCanBeSerialized()
    {
        $master = $this->getMockConnection('tcp://host1?alias=master');
        $slave1 = $this->getMockConnection('tcp://host2?alias=slave1');

        $replication = new MasterSlaveReplication();
        $replication->add($master);
        $replication->add($slave1);

        $unserialized = unserialize(serialize($replication));

        $this->assertEquals($master, $unserialized->getConnectionById('master'));
        $this->assertEquals($slave1, $unserialized->getConnectionById('slave1'));
    }

    // ******************************************************************** //
    // ---- HELPER METHODS ------------------------------------------------ //
    // ******************************************************************** //

    /**
     * Returns a base mocked connection from Predis\Connection\NodeConnectionInterface.
     *
     * @param mixed $parameters Optional parameters.
     *
     * @return mixed
     */
    protected function getMockConnection($parameters = null)
    {
        $connection = $this->getMock('Predis\Connection\NodeConnectionInterface');

        if ($parameters) {
            $parameters = Connection\Parameters::create($parameters);
            $hash = "{$parameters->host}:{$parameters->port}";

            $connection->expects($this->any())
                       ->method('getParameters')
                       ->will($this->returnValue($parameters));
            $connection->expects($this->any())
                       ->method('__toString')
                       ->will($this->returnValue($hash));
        }

        return $connection;
    }
}