unknownnf / acme-cart

Acme Widget Co

Acme Widget Co are the leading provider of made up widgets, and they’ve contracted you to create a proof of concept for their new sales system.

They sell three products –

Product	Code	Price
Red Widget	R01	$32.95
Green Widget	G01	$24.95
Blue Widget	B01	$7.95

To incentive customers to spend more, delivery costs are reduced based on the amount spent. Orders under $50 cost $4.95. For orders under $90, delivery costs $2.95. Orders of $90 or more have free delivery.

They are also experimenting with special offers. The initial offer will be “buy one red widget, get the second half price”.

Requirements

• PHP 8.0
• Composer
• Codeception for testing

Assumptions

• No persistence of data or sessions is necessary, repository pattern is used to encapsulate products and cart items
• Product code is unique.
• There can only be a single cart item per product.
• The first shipping method that is applicable is used.
• The cart can have more than one sales rule.
• Total discount offered every n-th item is variable.
• Totals are only calculated when items are added or removed to the cart.

Usage

use Acme\Sales\Entity\Cart;
use Acme\Sales\Entity\Product;
use Acme\Sales\Entity\Sales\Rule\NthPercentOffRule;
use Acme\Sales\Entity\Shipping\Method\OrderTotalBased;

// Create a new cart
$cart = new Cart();

// Instantiate catalog for the cart
$cart->getCatalog()->add(new Product('R01', 'Red Widget', 32.95));
$cart->getCatalog()->add(new Product('G01', 'Green Widget', 24.95));
$cart->getCatalog()->add(new Product('B01', 'Blue Widget', 7.95));

// Add a sales rule, every second product with code will be half price.
$cart->addSalesRule(
    new NthPercentOffRule('R01', 2, 0.5)
);

// Add available shipping methods to the cart.
$cart->addShippingMethod(
    new OrderTotalBased(0, 50, 4.95)
);
$cart->addShippingMethod(
    new OrderTotalBased(50, 90, 2.95)
);
$cart->addShippingMethod(
    new OrderTotalBased(90, null, 0)
);

// Add a product to the cart by product code
$cart->addProduct('R01');

// Get the calculated grand total
$grandTotal = $cart->getGrandTotal();

// Adding the same product to the cart twice increases quantity
$cart->addProduct('R01');

// Get the calculated grand total
$grandTotal = $cart->getGrandTotal();

// Totals available:
$subTotal = $cart->getSubTotal();
$discountTotal = $cart->getDiscountTotal();
$shippingTotal = $cart->getShippingTotal();

$cart->addProduct('G01');

// Return list of available items
$items = $cart->getItems();

foreach ($items as $item) {
    // Get the total of the row
    $rowTotal = $item->getTotal()
}

// Remove an item from the cart
$cart->removeProduct('R01');

Tests

Unit tests can be with docker using docker-compose run --rm codecept run unit, acceptance tests are run on docker start after the web container is online.

If docker is not available codeception can be used, first install dependencies by running composer install in the project folder then vendor/bin/codecept run unit would go through all unit tests.

Unit Tests (23)

✔ ShippingOrderBasedTotalTest: Is applicable (0.01s)
✔ CartTest: Remove item (0.00s)
✔ CartTest: Add product (0.00s)
✔ CartTest: Can instantiate (0.00s)
✔ CartTest: Scenario two blue three red (0.00s)
✔ CartItemTest: Cart item total (0.00s)
✔ CartTest: Totals (0.00s)
✔ SalesNthPercentOffRuleTest: Discount amounts (0.00s)
✔ SalesNthPercentOffRuleTest: Implements rule interface (0.00s)
✔ SalesNthPercentOffRuleTest: Can instantiate (0.00s)
✔ CartItemTest: Can instantiate (0.00s)
✔ CartTest: Scenario one blue one green (0.00s)
✔ SalesNthPercentOffRuleTest: Is applicable (0.00s)
✔ CartTest: Scenario one green one red (0.00s)
✔ CartTest: Add item (0.00s)
✔ ShippingOrderBasedTotalTest: Implements shipping interface (0.00s)
✔ ShippingOrderBasedTotalTest: Shipping cost (0.00s)
✔ ShippingOrderBasedTotalTest: Can instantiate (0.00s)
✔ CartTest: Scenario two red (0.00s)
✔ CartTest: Add cart rules (0.00s)
✔ CartTest: Add shipping method (0.00s)
✔ ProductTest: Can instantiate (0.00s)
✔ CartTest: Cannot add missing product (0.00s)

Time: 00:00.026, Memory: 10.00 MB
OK (23 tests, 66 assertions)