流暢介面，常用於撰寫如同文章般容易閱讀的程式碼，如果以大頭菜來講，那麼在建立大頭菜的同時，希望可以順便賦予其鈴錢價格、數量，並且最終獲得的依舊是大頭菜物件。
這次只需要實作一個大頭菜物件，其精隨在於賦予鈴錢價格、數量時，最後會將整個物件再回傳出來，透過被呼叫的方法來回傳當前物件。
Turnips.php
/**
* Class Turnips.
*/
class Turnips
{
/**
* @var int
*/
protected $price = 0;
/**
* @var int
*/
protected $count = 0;
/**
* @param int $price
*
* @return Turnips
*/
public function price(int $price): Turnips
{
$this->price = $price;
return $this;
}
/**
* @param int $count
*
* @return Turnips
*/
public function count(int $count): Turnips
{
$this->count = $count;
return $this;
}
/**
* @return int
*/
public function calculatePrice(): int
{
return $this->price * $this->count;
}
}我們要來實際測試大頭菜是否能夠以流暢介面的方式來建立物件，並且計算鈴錢總價。
FluentInterfaceTest.php
/**
* Class FluentInterfaceTest.
*/
class FluentInterfaceTest extends TestCase
{
/**
* @test
*/
public function test_build_turnips()
{
$turnips = (new Turnips())
->price(100)
->count(40);
$this->assertEquals(4000, $turnips->calculatePrice());
}
}最後測試的執行結果會獲得如下：
PHPUnit Pretty Result Printer 0.28.0 by Codedungeon and contributors.
==> Configuration: ~/php-design-pattern/vendor/codedungeon/phpunit-result-printer/src/phpunit-printer.yml
PHPUnit 9.2.6 by Sebastian Bergmann and contributors.
==> AbstractFactoryTest ✔ ✔ ✔ ✔
==> BuilderPatternTest ✔ ✔ ✔ ✔
==> FactoryMethodTest ✔ ✔ ✔ ✔
==> PoolPatternTest ✔ ✔
==> PrototypePatternTest ✔ ✔
==> SimpleFactoryTest ✔ ✔ ✔ ✔
==> SingletonPatternTest ✔
==> StaticFactoryTest ✔ ✔ ✔ ✔ ✔
==> AdapterPatternTest ✔ ✔
==> BridgePatternTest ✔ ✔ ✔
==> CompositePatternTest ✔ ✔ ✔
==> DataMapperTest ✔ ✔
==> DecoratorPatternTest ✔ ✔
==> DependencyInjectionTest ✔ ✔ ✔
==> FacadePatternTest ✔
==> FluentInterfaceTest ✔
Time: 00:00.079, Memory: 6.00 MB
OK (43 tests, 94 assertions)