Are there any specific PHPUnit features or functionalities that are particularly useful for testing complex PHP applications like an online shop?

When testing complex PHP applications like an online shop, it's important to utilize PHPUnit features such as data providers, mocking, and assertions to ensure thorough testing coverage. Data providers can help streamline testing by providing different sets of data to test a single method with various inputs. Mocking can be used to simulate external dependencies, such as database connections or API calls, to isolate the code being tested. Assertions are crucial for verifying that the expected outcomes of the code are met during testing.

// Example of using data providers in PHPUnit to test a method with multiple inputs

class ShoppingCartTest extends \PHPUnit\Framework\TestCase
{
    /**
     * @dataProvider itemProvider
     */
    public function testAddItemToCart($item, $quantity, $expectedTotal)
    {
        $cart = new ShoppingCart();
        $cart->addItem($item, $quantity);
        
        $this->assertEquals($expectedTotal, $cart->getTotal());
    }
    
    public function itemProvider()
    {
        return [
            ['Product A', 2, 20], // item, quantity, expectedTotal
            ['Product B', 1, 10],
            ['Product C', 3, 30],
        ];
    }
}