PHPUnit : memcache_connect not working in PHPunit test case - php

Question

Note:all code working fine without phpunit
file 1:common.php:
public function setNIMUID( $NIMUID ) {
if(is_bool(Cache::get("$NIMUID"))) {
$user_Array=array("_JID"=>(string)$NIMUID);
Cache::set("$NIMUID",$user_Array);
}
$this->NIMUID=(string)$NIMUID ;
}
File 2 :memcache.class.php
method 1:
protected function __construct(array $servers) {
if(!$servers) {
trigger_error('No memcache servers to connect', E_USER_WARNING);
}
for($i = 0, $n = count($servers); $i<$n; ++ $i) {
($con = memcache_connect(key($servers[$i]), current($servers[$i])))&&$this->mc_servers[] = $con;
}
$this->mc_servers_count = count($this->mc_servers);
if(!$this->mc_servers_count) {
$this->mc_servers[0] = null;
}
}
method 2:
static function get($key) {
return self::singleton()->getMemcacheLink($key)->get($key);
}
method 3:
static function singleton() {
//Write here where from to get the servers list from, like
global $memcache_servers;
self::$instance||self::$instance = new Cache($memcache_servers);
return self::$instance;
}
File 3 : commonTest.php
public function testCommon()
{
$Common = new Common();
$Common->setNIMUID("saurabh4");
}
$memcache_servers variable :
$memcache_servers = array(
array('localhost'=>'11211'),
array('127.0.0.1'=>'11211')
);
Error :
Fatal error: Call to undefined function memcache_connect()

Answer 1

Unit tests should be repeatable, fast and isolated. That means that you shouldn't connect to external services to unit test your classes.
If you want to test that Common is working fine, you should test its behaviour, which in this case is that is calling the Cache class as you'd expect.
For that, you'll need to use mocks. With mocks you can set some expectations, like that the object will be called in a specific manner. If your class is called the memcached class as expected, you can assume your functionality is working fine. How do you know the Cache class is working fine? Because the Cache class would have its own unit test.
In order to use mocks (or stubs), you need to change the way you program and avoid static calles like the one in Cache::set(). Instead, you should use class instances and normal calls. How? Passing the Cache instance to your Common class. This concept is called Dependency injection. Your Common code would look like this:
public function __construct( $cache ) {
$this->cache = $cache;
}
public function setNIMUID( $NIMUID ) {
if(is_bool($this->cache->get("$NIMUID"))) {
$user_Array=array("_JID"=>(string)$NIMUID);
$this->cache->set("$NIMUID",$user_Array);
}
$this->NIMUID=(string)$NIMUID ;
}