How to mock PDO for test-cases written in PHPUnit

phpunit_pdo_mock.php

<?php

// ...
protected function getMockedPDO()
{
       $query = $this->getMock('\PDOStatement');
       $query->method('execute')->willReturn(true);

       $db = $this->getMockBuilder('\PDO')
           ->disableOriginalConstructor()
           ->setMethods(['prepare'])
           ->getMock();

       $db->method('prepare')->willReturn($query);

       return $db;

  }