Add swell provider folder

framework/swell/cart/utils/checkout-to-cart.ts

@@ -0,0 +1,42 @@
+import { Cart } from '../../types'
+import { CommerceError, ValidationError } from '@commerce/utils/errors'
+
+import {
+  CheckoutLineItemsAddPayload,
+  CheckoutLineItemsRemovePayload,
+  CheckoutLineItemsUpdatePayload,
+  Maybe,
+} from '../../schema'
+import { normalizeCart } from '../../utils'
+
+export type CheckoutPayload =
+  | CheckoutLineItemsAddPayload
+  | CheckoutLineItemsUpdatePayload
+  | CheckoutLineItemsRemovePayload
+
+const checkoutToCart = (checkoutPayload?: Maybe<CheckoutPayload>): Cart => {
+  if (!checkoutPayload) {
+    throw new CommerceError({
+      message: 'Invalid response from Shopify',
+    })
+  }
+
+  const checkout = checkoutPayload?.checkout
+  const userErrors = checkoutPayload?.userErrors
+
+  if (userErrors && userErrors.length) {
+    throw new ValidationError({
+      message: userErrors[0].message,
+    })
+  }
+
+  if (!checkout) {
+    throw new CommerceError({
+      message: 'Invalid response from Shopify',
+    })
+  }
+
+  return normalizeCart(checkout)
+}
+
+export default checkoutToCart