ClassTest.php
<?php
require_once 'UserClass.php';

class ClassTest extends PHPUnit\Framework\TestCase {

    public function testClassReturnsValidValue()
    {
        $class = new UserClass('samy','samy@gmail.com');

        $this->assertEquals('samy', $class->getName());
    }

    public function testClassChangeValue()
    {
        $class = new UserClass('samy','samy@gmail.com');

        $this->assertEquals('ahmed', $class->setName('ahmed'));
    }

public function testClassEmailValue()
    {
        $class = new UserClass('samy','samy@gmail.com');

        $this->assertEquals('samy@gmail.com', $class->getEmail());
    }

public function testClassChangeEmailValue()
    {
        $class = new UserClass('samy','samy@gmail.com');

        $this->assertEquals('ahmed@gmail.com', $class->setEmail('ahmed@gmail.com'));
    }

}
/*****************************************************************************/

Factorial.php
<?php
class Factorial
{
    protected $_number;

    public function __construct($number)
    {
        if (!is_int($number))
        {
            throw new InvalidArgumentException('Missing argument or not a number');
        }

        $this->_number = $number;
    }

    public function getResult()
    {
        $factorial = 1;

        for ($i = 1; $i <= $this->_number; $i++)
        {
            $factorial *= $i;
        }

        return $factorial;
    }
}
/****************************************************/
SampleTest.php
<?php
require_once('Factorial.php');

     class SampleTest extends PHPUnit\Framework\TestCase {
    public function testFactorialOfNumberOne()
        {
        $factorial = new Factorial(1);

        $this->assertEquals(1, $factorial->getResult());
        }

    public function testFactorialOfNumberZero()
        {
        $factorial = new Factorial(0);

        $this->assertEquals(1, $factorial->getResult());
        }
    public function testFactorialOfNumberFive()
        {
        $factorial = new Factorial(5);

        $this->assertEquals(120, $factorial->getResult());
        }
     }

/*****************************************/
UserClass.php
<?php
class UserClass
{
    protected $_name,$_email;

    public function __construct($name,$email)
    {
        $this->_name = $name;
    $this->_email = $email;
    }

    public function getName()
    {
        return $this->_name;
    }

   public function setName($name)
    {
        return $this->_name = $name;
    }

   public function getEmail()
    {
        return $this->_email;
    }

   public function setEmail($email)
    {
        return $this->_email = $email;
    }
}