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:
class Temperature
{
private $service;
public function __construct($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.
use \Mockery;
class TemperatureTest extends PHPUnit_Framework_TestCase
{
public function tearDown()
{
Mockery::close();
}
public function testGetsAverageTemperatureFromThreeServiceReadings()
{
$service = Mockery::mock('service');
$service->shouldReceive('readTemp')
->times(3)
->andReturn(10, 12, 14);
$temperature = new Temperature($service);
$this->assertEquals(12, $temperature->average());
}
}
We create a mock object which our Temperature
class will use and set some expectations for that mock — that it should receive three calls to the readTemp
method, and these calls will return 10, 12, and 14 as results.
Note
PHPUnit integration can remove the need for a tearDown()
method. See "/reference/phpunit_integration
" for more information.