用PDO模拟进行phpunit测试

Question

i am trying to test a class with two methods. both interact with a database which is the why im am trying to work with PDO mock object. I couldn't find much documentation about mocking PDO object and working with them but after following one tutorial that looked pretty close to what i need i ended up with a PDO mock object, but i don't understand how should i use it.

to make thing simple this is my class with the first method i want to test:

<?php
use Slim\Slim;

class AdProviders {
  public $providers = null;

  protected $db = null;

  function __construct() {

  }

  function getDbh() {
    if ($this->db === null){
      $this->db = Slim::getInstance()->db;
    }
    return $this->db->getConnection();
  }

}

and according to the db schema this is how i created the PDO object:

<?php
require dirname(__FILE__).'/../../src/vendor/autoload.php';

class AdProvidersTest extends PHPUnit_Framework_TestCase
{
    public function dataProvider()
    {
        return array (
            array (1, '1st', 'desc_1', 11),
            array (2, '2nd', 'desc_2', 22),
            array (3, '3rd', 'desc_3', 33),
        );
    }
    /**
     * @dataProvider dataProvider
     */
    public function testAdProviders($id, $name, $desc, $account_id)
    {
        $data = array (
            array (
                'id' => $id,
                'name' => $name,
                'description' => $desc,
                'account_id' => $account_id
            )
        );

        $stmt = $this->getMock('PDOStatement', array ('fetchAll'));
        $stmt->expects($this->any())
             ->method('fetchAll')
             ->will($this->returnValue($data));

        $pdo = $this->getMock('PDO', array('prepare'),
            array('sqlite:dbname=:memory'),'PDOMock_' . uniqid(),true);
        $pdo->expects($this->any())
            ->method('prepare')
            ->will($this->returnValue($stmt));

    }
}

Now i am really lost with how should i test the getDbh() method ... is this the correct way to create a PDO mock for the purpose of my test? and if so, how can i use it to test the method?

any kind of guidance will be highly appreciated... thx

Answer 1

You need to inject this mock into Slim::getInstance() that is why it is bad to use singletons and better to use dependency injection pattern.

It is kind a senseless to mock PDO where you can't change PDO in Slim::getInstance()->db

What you really may test here is whether method getDbh() returns instance of Connection.