Test double examples

DoublesTest.php

<?php declare(strict_types=1);

namespace App\Tests\Doubles;

use PHPUnit\Framework\TestCase;

class Item
{
}

interface Basket
{
    /**
     * @return Item[]
     */
    public function items(): array;

    public function add(Item $item): void;
}

class Foo
{
    private $basket;

    public function __construct(Basket $basket)
    {
        $this->basket = $basket;
    }

    public function a(): bool
    {
        return true;
    }

    public function b(): array
    {
        return $this->basket->items();
    }

    public function c(Item $item): void
    {
        $this->basket->add($item);
    }
}

class DoublesTest extends TestCase
{
    public function test_custom_dummy()
    {
        $basketDummy = new class implements Basket {
            public function items(): array
            {
            }

            public function add(Item $item): void
            {
            }
        };

        $foo = new Foo($basketDummy);

        $this->assertTrue($foo->a());
    }

    public function test_prophecy_dummy()
    {
        $basketDummy = $this->prophesize(Basket::class);

        $foo = new Foo($basketDummy->reveal());

        $this->assertTrue($foo->a());
    }

    public function test_phpunit_dummy()
    {
        $basketDummy = $this->createMock(Basket::class);

        $foo = new Foo($basketDummy);

        $this->assertTrue($foo->a());
    }

    public function test_custom_stub()
    {
        $items = [new Item(), new Item()];

        $basketStub = new class($items) implements Basket {
            private $items;

            public function __construct(array $items)
            {
                $this->items = $items;
            }

            public function items(): array
            {
                return $this->items;
            }

            public function add(Item $item): void
            {
            }
        };

        $foo = new Foo($basketStub);

        $this->assertSame($items, $foo->b());
    }

    public function test_prophecy_stub()
    {
        $items = [new Item(), new Item()];

        $basketStub = $this->prophesize(Basket::class);
        $basketStub->items()->willReturn($items);

        $foo = new Foo($basketStub->reveal());

        $this->assertSame($items, $foo->b());
    }

    public function test_phpunit_stub()
    {
        $items = [new Item(), new Item()];

        $basketStub = $this->createMock(Basket::class);
        $basketStub->expects($this->any())
            ->method('items')
            ->willReturn($items);

        $foo = new Foo($basketStub);

        $this->assertSame($items, $foo->b());

    }

    public function test_custom_mock_object()
    {
        $item = new Item();

        $basketMock = new class implements Basket {
            public $addedItem;

            public function items(): array
            {
            }

            public function add(Item $item): void
            {
                $this->addedItem = $item;
            }

            public function __destruct()
            {
                if (null === $this->addedItem) {
                    throw new \LogicException('Expected "add" method to be called.');
                }
            }
        };

        $foo = new Foo($basketMock);
        $foo->c($item);
    }

    public function test_prophecy_mock_object()
    {
        $item = new Item();

        $basketMock = $this->prophesize(Basket::class);
        $basketMock->add($item)->shouldBeCalled();

        $foo = new Foo($basketMock->reveal());
        $foo->c($item);
    }

    public function test_phpunit_mock_object()
    {
        $item = new Item();

        $basketMock = $this->createMock(Basket::class);
        $basketMock->expects($this->once())
            ->method('add')
            ->with($item);

        $foo = new Foo($basketMock);
        $foo->c($item);
    }

    public function test_custom_spy()
    {
        $item = new Item();

        $basketSpy = new class implements Basket {
            public $addedItem;

            public function items(): array
            {
            }

            public function add(Item $item): void
            {
                $this->addedItem = $item;
            }
        };

        $foo = new Foo($basketSpy);
        $foo->c($item);

        $this->assertSame($item, $basketSpy->addedItem);
    }

    public function test_prophecy_spy()
    {
        $item = new Item();

        $basketSpy = $this->prophesize(Basket::class);

        $foo = new Foo($basketSpy->reveal());
        $foo->c($item);

        $basketSpy->add($item)->shouldHaveBeenCalled();
    }

    public function test_phpunit_spy()
    {
        // there is a way, but it’s ugly. Google “spying with phpunit"
    }

    public function test_fake_object()
    {
        $item = new Item();

        $basketFake = new class implements Basket {
            private $items = [];

            public function items(): array
            {
                return $this->items;
            }

            public function add(Item $item): void
            {
                $this->items[] = $item;
            }
        };

        $foo = new Foo($basketFake);
        $foo->c($item);

        $this->assertSame([$item], $foo->b());
    }

    public function test_prophecy_fake_object()
    {
        $item = new Item();

        $basketFake = $this->prophesize(Basket::class);
        $basketFake->add($item)->will(function ($args) {
            $this->items()->willReturn([$args[0]]);
        });

        $foo = new Foo($basketFake->reveal());
        $foo->c($item);

        $this->assertSame([$item], $foo->b());
    }

    public function test_phpunit_fake_object()
    {
        $item = new Item();

        $basketFake = $this->createMock(Basket::class);
        $basketFake->method('add')
            ->with($item)
            ->will($this->returnCallback(function (Item $item) use ($basketFake) {
                $basketFake->method('items')->willReturn([$item]);
            }));

        $foo = new Foo($basketFake);
        $foo->c($item);

        $this->assertSame([$item], $foo->b());
    }
}