EVOLUTION-MANAGER

Edit File: simple_example.rst

.. index::
    single: Getting Started; Simple Example

Simple Example
==============

Imagine we have a ``Temperature`` class which samples the temperature of a
locale before reporting an average temperature. The data could come from a web
service or any other data source, but we do not have such a class at present.
We can, however, assume some basic interactions with such a class based on its
interaction with the ``Temperature`` class:

.. code-block:: php

class Temperature
    {

public function __construct($service)
        {
            $this->_service = $service;
        }

public function average()
        {
            $total = 0;
            for ($i=0;$i<3;$i++) {
                $total += $this->_service->readTemp();
            }
            return $total/3;
        }

}

Even without an actual service class, we can see how we expect it to operate.
When writing a test for the ``Temperature`` class, we can now substitute a
mock object for the real service which allows us to test the behaviour of the
``Temperature`` class without actually needing a concrete service instance.

.. code-block:: php

use \Mockery as m;

class TemperatureTest extends PHPUnit_Framework_TestCase
    {

public function tearDown()
        {
            m::close();
        }

public function testGetsAverageTemperatureFromThreeServiceReadings()
        {
            $service = m::mock('service');
            $service->shouldReceive('readTemp')->times(3)->andReturn(10, 12, 14);

$temperature = new Temperature($service);

$this->assertEquals(12, $temperature->average());
        }

}

.. note::

PHPUnit integration can remove the need for a ``tearDown()`` method. See
    ":doc:`/reference/phpunit_integration`" for more information.