Initial work, copied from the Shopify provider

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

@@ -0,0 +1,48 @@
+import { Cart } from '../types'
+import { CommerceError } from '@commerce/utils/errors'
+
+import {
+  CheckoutLineItemsAddPayload,
+  CheckoutLineItemsRemovePayload,
+  CheckoutLineItemsUpdatePayload,
+  CheckoutCreatePayload,
+  CheckoutUserError,
+  Checkout,
+  Maybe,
+} from '../schema'
+
+import { normalizeCart } from './normalize'
+import throwUserErrors from './throw-user-errors'
+
+export type CheckoutQuery = {
+  checkout: Checkout
+  checkoutUserErrors?: Array<CheckoutUserError>
+}
+
+export type CheckoutPayload =
+  | CheckoutLineItemsAddPayload
+  | CheckoutLineItemsUpdatePayload
+  | CheckoutLineItemsRemovePayload
+  | CheckoutCreatePayload
+  | CheckoutQuery
+
+const checkoutToCart = (checkoutPayload?: Maybe<CheckoutPayload>): Cart => {
+  if (!checkoutPayload) {
+    throw new CommerceError({
+      message: 'Missing checkout payload from response',
+    })
+  }
+
+  const checkout = checkoutPayload?.checkout
+  throwUserErrors(checkoutPayload?.checkoutUserErrors)
+
+  if (!checkout) {
+    throw new CommerceError({
+      message: 'Missing checkout object from response',
+    })
+  }
+
+  return normalizeCart(checkout)
+}
+
+export default checkoutToCart