public function testReplace()
 {
     $testKey = 'abc000';
     $testValue = 'start';
     $testReplaceValue = '_end';
     $mock = new MemcachedMock();
     $this->assertFalse($mock->replace($testKey, $testValue));
     $mock->addServer('127.0.0.1', 11211);
     $this->assertFalse($mock->replace(null, $testValue));
     $this->assertFalse($mock->replace($testKey, '1'));
     $mock->set($testKey, $testValue);
     $this->assertTrue($mock->replace($testKey, $testReplaceValue));
     $this->assertSame($testReplaceValue, $mock->get($testKey));
     $this->assertFalse($mock->replace($testKey, xml_parser_create('')));
     $this->assertFalse($mock->replace($testKey, $testReplaceValue, 'invalid'));
     $this->assertTrue($mock->replace($testKey, $testReplaceValue, 10));
     $this->assertSame(time() + 10, $mock->getExpiry($testKey));
 }