Product totals calculating to $0.00 when adding products to cart programmatically

I had this problem recently where the cart page was displaying $0.00 on all the product line items after I had programmatically added 3 products to my cart. I didn’t find a solution after a quick Google search, so after lots of CMD+B in PHPStorm and reading the checkout/cart/add controller, I had my solution. The block of code below is a re-creation of what I was doing to add these products to my cart.

/**
 * @var \Magento\Checkout\Model\Cart
 */
protected $customerCart;

/**
 * @var \Magento\Catalog\Model\ProductFactory
 */
protected $productFactory;

public function execute()
{
    $productIds = ['1', '2', '3'];

    $productCollection = $this->productFactory->create()
        ->getCollection()
        ->addFieldToFilter('entity_id', ['in' => $productIds])
        ->addWebsiteFilter($this->storeManager->getWebsite()->getId());

    foreach ($productCollection as $product) {
        $this->customerCart->addProduct($product, [
            'qty' => 1
        ]);
    }

    $this->customerCart->save();
}

->addAttributeToSelect('*'); to the collection, and my totals were calculating correctly again.

$this->customerCart->save(), the quote begins $quote->collectTotals(). Because the price attribute was never loaded when I executed the collection, when $product->getData('price') returns NULL and ends up calculating all of the totals to $0.00.

You may ask “why select all attributes instead of just the price attribute?” I noticed that in the /checkout/cart/add controller, the product is loaded via the Magento\Catalog\Model\ProductRepository, which also loads all product attributes. Any third party module can also inject their own totals collector, and you never know what attributes they could need during calculations.