Builds a clear specification of business rules, where objects can be checked against.
Specification.php
<?php
namespace Kuriv\PHPDesignPatterns\Behavioral\Specification;
interface Specification
{
/**
* Return the result of inspect.
*
* @param Item $item
* @return bool
*/
public function inspect(Item $item): bool;
}PriceSpecification.php
<?php
namespace Kuriv\PHPDesignPatterns\Behavioral\Specification;
class PriceSpecification implements Specification
{
/**
* Store the min price.
*
* @var float
*/
private float $min;
/**
* Store the min price.
*
* @var float
*/
private float $max;
/**
* Store the min price and max price to the current instance.
*
* @param float $min
* @param float $max
* @return void
*/
public function __construct(float $min, float $max)
{
$this->min = $min;
$this->max = $max;
}
/**
* Return the result of inspect.
*
* @param Item $item
* @return bool
*/
public function inspect(Item $item): bool
{
$price = $item->getPrice();
return $price >= $this->min && $price <= $this->max;
}
}OrSpecification.php
<?php
namespace Kuriv\PHPDesignPatterns\Behavioral\Specification;
class OrSpecification implements Specification
{
/**
* Store several specification instances.
*
* @var array
*/
private array $specifications = [];
/**
* Store several specification instances to the current instance.
*
* @param Specification $specifications
* @return void
*/
public function __construct(Specification ...$specifications)
{
$this->specifications = $specifications;
}
/**
* Return the result of inspect.
*
* @param Item $item
* @return bool
*/
public function inspect(Item $item): bool
{
foreach ($this->specifications as $specification) {
if ($specification->inspect($item)) {
return true;
}
}
return false;
}
}AndSpecification.php
<?php
namespace Kuriv\PHPDesignPatterns\Behavioral\Specification;
class AndSpecification implements Specification
{
/**
* Store several specification instances.
*
* @var array
*/
private array $specifications = [];
/**
* Store several specification instances to the current instance.
*
* @param Specification $specifications
* @return void
*/
public function __construct(Specification ...$specifications)
{
$this->specifications = $specifications;
}
/**
* Return the result of inspect.
*
* @param Item $item
* @return bool
*/
public function inspect(Item $item): bool
{
foreach ($this->specifications as $specification) {
if (!$specification->inspect($item)) {
return false;
}
}
return true;
}
}NotSpecification.php
<?php
namespace Kuriv\PHPDesignPatterns\Behavioral\Specification;
class NotSpecification implements Specification
{
/**
* Store the specification instance.
*
* @var Specification
*/
private Specification $specification;
/**
* Store the specification instance to the current instance.
*
* @param Specification $specification
* @return void
*/
public function __construct(Specification $specification)
{
$this->specification = $specification;
}
/**
* Return the result of inspect.
*
* @param Item $item
* @return bool
*/
public function inspect(Item $item): bool
{
return !$this->specification->inspect($item);
}
}Item.php
<?php
namespace Kuriv\PHPDesignPatterns\Behavioral\Specification;
class Item
{
/**
* Store the price.
*
* @var float
*/
private float $price;
/**
* Store the price to the current instance.
*
* @param float $price
* @return void
*/
public function __construct(float $price)
{
$this->price = $price;
}
/**
* Get the price.
*
* @param void
* @return float
*/
public function getPrice(): float
{
return $this->price;
}
}SpecificationTest.php
<?php
namespace Kuriv\PHPDesignPatterns\Behavioral\Specification;
use PHPUnit\Framework\TestCase;
class SpecificationTest extends TestCase
{
public function testCanOr()
{
$firstPriceSpecification = new PriceSpecification(50, 99);
$secondPriceSpecification = new PriceSpecification(101, 200);
$orSpecification = new OrSpecification($firstPriceSpecification, $secondPriceSpecification);
$this->assertFalse($orSpecification->inspect(new Item(100)));
$this->assertTrue($orSpecification->inspect(new Item(51)));
$this->assertTrue($orSpecification->inspect(new Item(150)));
}
public function testCanAnd()
{
$firstPriceSpecification = new PriceSpecification(50, 100);
$secondPriceSpecification = new PriceSpecification(80, 200);
$andSpecification = new AndSpecification($firstPriceSpecification, $secondPriceSpecification);
$this->assertFalse($andSpecification->inspect(new Item(150)));
$this->assertFalse($andSpecification->inspect(new Item(1)));
$this->assertFalse($andSpecification->inspect(new Item(51)));
$this->assertTrue($andSpecification->inspect(new Item(100)));
}
public function testCanNot()
{
$priceSpecification = new PriceSpecification(50, 100);
$notSpecification = new NotSpecification($priceSpecification);
$this->assertTrue($notSpecification->inspect(new Item(150)));
$this->assertFalse($notSpecification->inspect(new Item(50)));
}
}