nopolabs/mock-with-expectations

Helper trait for phpunit testing

MockWithExpectations

, _(*1)

This package provides a more concise notation for building mock objects in a sub-class of PHPUnit\Framework\TestCase., _(*2)

I like testing with mocks and expectations. It lets me test my code without having to test the components with which it interacts. Those components need to be tested too, but I want my tests focused on one thing at a time., _(*3)

Consider this refundOrder() function:, _(*4)

public function refundOrder($orderId)
{
    $order = $this->orderRepository->findOrder($orderId);
    if ($order->isRefundable()) {
        $this->orderRefunder->refund($order);
    }
}

Here is a PHPUnit test for refundOrder():, _(*5)

public function testRefundOrder()
{
    $orderId = 1337;
    $order = $this->createMock(Order::class);
    $orderRepository = $this->createMock(OrderRepository::class);
    $orderRefunder = $this->createMock(OrderRefunder::class);

    $orderRepository->expects($this->once())
        ->method('findOrder')
        ->with($orderId)
        ->willReturn($order);

    $order->expects($this->once())
        ->method('isRefundable')
        ->willReturn(true);

    $orderRefunder->expects($this->once())
        ->method('refund')
        ->with($order);

    $manager = new OrderManager($orderRepository, $orderRefunder);

    $manager->refundOrder($orderId);
}

And using MockWithExpectationsTrait:, _(*6)

use MockWithExpectationsTrait;

public function testRefundOrder()
{
    $orderId = 1337;

    $order = $this->createMockWithExpectations(Order::class, [
        ['isRefundable', [], true],
    ]);

    $orderRepository = $this->createMockWithExpectations(OrderRepository::class, [
        ['findOrder', [$orderId], $order],
    ]);

    $orderRefunder = $this->createMockWithExpectations(OrderRefunder::class, [
        ['refund', [$order]],
    ]);

    $manager = new OrderManager($orderRepository, $orderRefunder);

    $manager->refundOrder($orderId);
}

Refactoring refundOrder():, _(*7)

public function refundOrder($orderId)
{
    $order = $this->findOrder($orderId);
    if ($this->isRefundable($order)) {
        $this->refund($order);
    }
}

protected function findOrder($orderId) : Order
{
    return $this->orderRepository->findOrder($orderId);
}

protected function isRefundable(Order $order) : bool
{
    return $order->isRefundable();
}

protected function refund(Order $order)
{
    return $this->orderRefunder->refund($order);
}

And using MockWithExpectationsTrait:, _(*8)

use MockWithExpectationsTrait;

public function testRefundOrder()
{
    $orderId = 1337;
    $order = $this->createMock(Order::class);
    $manager = $this->createMockWithExpectations(OrderManager::class, [
        ['findOrder', [$orderId], $order],
        ['isRefundable', [$order], true],
        ['refund', [$order]],
    ]);
    $manager->refundOrder($orderId);
}

public function testRefundOrderNotRefundable()
{
    $orderId = 1337;
    $order = $this->createMock(Order::class);
    $manager = $this->createMockWithExpectations(OrderManager::class, [
        ['findOrder', [$orderId], $order],
        ['isRefundable', [$order], false],
        ['refund', 'never'],
    ]);
    $manager->refundOrder($orderId);
}

Using MockWithExpectationsTrait reduces the amount of boilerplate code needed to write the tests. In addition it uses the at() invocation matcher to ensure that the methods are called in the expected order. The original test does not check the order in which the methods are called., _(*9)

The way I look at it is this: testRefundOrder() is testing an external API exposed by OrderManager. In turn OrderManager composes functions method calls to several objects to implement the refundOrder() function. The refactoring organizes these calls as a single internal API. In this example the internal API is implemented as three protected methods on OrderManager. These methods are tools that help OrderManager to do its job of order management. As the internal order management API grows it might get moved to its own OrderManagement class, e.g.:, _(*10)

class OrderManagement
{
    private $orderRepository;
    private $orderRefunder;

    public __construct(OrderRepository $orderRepository, OrderRefunder $orderRefunder)
    {
        $this->orderRepository = $orderRepository;
        $this->orderRefunder = $orderRefunder;
    }

    public function findOrder($orderId) : Order
    {
        return $this->orderRepository->findOrder($orderId);
    }

    public function isRefundable(Order $order) : bool
    {
        return $order->isRefundable();
    }

    public function refund(Order $order)
    {
        return $this->orderRefunder->refund($order);
    }
}

class OrderManager
{
    private $orderManagement;

    public __construct(OrderManagement $orderManagement)
    {
        $this->orderManagement = $orderManagement;
    }

    public function refundOrder($orderId)
    {
        $order = $this->orderManagement->findOrder($orderId);
        if ($this->orderManagement->isRefundable($order)) {
            $this->orderManagement->refund($order);
        }
    }
}

class OrderManagerTest extends TestCase
{
    use MockWithExpectationsTrait;

    public function testRefundOrder()
    {
        $orderId = 1337;
        $order = $this->createMock(Order::class);
        $management = $this->createMockWithExpectations(OrderManagement::class, [
            ['findOrder', [$orderId], $order],
            ['isRefundable', [$order], true]
            ['refund', [$order]],
        ]);
        $manager = new OrderManager($management);

        $manager->refundOrder($orderId);
    }
}

Expectations Syntax

$expectationsList = [
    ['method', ['params'], 'result', 'throws', 'invoked'],
    ['calculate', ['foo, 'bar'], 42],
    [
        'method' => 'calculate',
        'params' => ['foo', 'bar'],
        'result' => 42,
        'throws' => null,
        'invoked' => TestCase::once(),
    ],
];

$expectationsMap = [
    'method' => [['params'], 'result', 'throws', 'invoked'],
];

method

params

result

throws

invoked

Using MockWithExpectationsTrait

composer require

composer require nopolabs/mock-with-expectations

methods

createMockWithExpectations

Creates a partial mock object and adds the provided expectations., _(*11)

addExpectation

Adds an expectation on a mock object., _(*12)

addExpectations

Adds expectations on a mock object., _(*13)