Worked thru (again) "codelab-initial-state".

codelab-initial-state/firestore.rules

@@ -3,14 +3,16 @@ service cloud.firestore {
   match /databases/{database}/documents {
     // User's cart metadata
     match /carts/{cartID} {
-      // TODO: Change these! Anyone can read or write.
-      allow read, write: if true;
+      // TODO: Changed so read or write only ownerUID == logged in auth UID.
+      allow create: if request.auth.uid == request.resource.data.ownerUID;
+      allow read, update, delete: if request.auth.uid == resource.data.ownerUID;
     }
 
     // Items inside the user's cart
     match /carts/{cartID}/items/{itemID} {
       // TODO: Change these! Anyone can read or write.
-      allow read, write: if true;
+      // allow read, write: if false;
+      allow read, write: if get(/databases/$(database)/documents/carts/$(cartID)).data.ownerUID == request.auth.uid;
     }
 
     // All items available in the store. Users can read

codelab-initial-state/functions/index.js

@@ -27,16 +27,37 @@ exports.calculateCart = functions
         return;
       }
 
-      let totalPrice = 125.98;
-      let itemCount = 8;
+      let totalPrice = 0; //125.98;
+      let itemCount = 0; //9;
       try {
-
         const cartRef = db.collection("carts").doc(context.params.cartId);
+        const itemsSnap = await cartRef.collection("items").get();
+
+        itemsSnap.docs.forEach(item => {
+          const itemData = item.data();
+          if (itemData.price) {
+            // If not specified, the quantity is 1
+            const quantity = itemData.quantity ? itemData.quantity : 1;
+            itemCount += quantity;
+            totalPrice += (itemData.price * quantity);
+          }
+        });
 
         await cartRef.update({
           totalPrice,
           itemCount
         });
-      } catch(err) {
-      }
-    });
+
+          console.log("Cart total successfully recalculated!");
+        } catch(err) {
+         console.warn("update error", err);
+        }
+      });
+
+
+
+
+
+
+
+

codelab-initial-state/functions/test.js

@@ -17,7 +17,8 @@ const path = require("path");
 const TEST_FIREBASE_PROJECT_ID = "test-firestore-rules-project";
 
 // TODO: Change this to your real Firebase Project ID
-const REAL_FIREBASE_PROJECT_ID = "changeme";
+// CF: is this the correct PROJECT_ID?
+const REAL_FIREBASE_PROJECT_ID = "marmalade-beta"; //"changeme";
 
 const firebase = require("@firebase/rules-unit-testing");
 
@@ -179,7 +180,7 @@ describe("shopping cart items", async () => {
   });
 });
 
-describe.skip("adding an item to the cart recalculates the cart total. ", () => {
+describe("adding an item to the cart recalculates the cart total. ", () => {
   const admin = firebase.initializeAdminApp({ 
     projectId: REAL_FIREBASE_PROJECT_ID 
   }).firestore();

codelab-initial-state/public/js/homepage.js

@@ -28,6 +28,12 @@ export async function onDocumentReady(firebaseApp) {
   const auth = firebaseApp.auth();
   const db = firebaseApp.firestore();
 
+  if (location.hostname === "127.0.0.1") {
+    console.log("127.0.0.1 detected!");
+    auth.useEmulator("http://127.0.0.1:9099");
+    db.useEmulator("127.0.0.1", 8080);
+  }
+
   const homePage = new HomePage(db, auth);
   mount(document.body, homePage);
 }
@@ -170,6 +176,10 @@ class HomePage {
   }
 
   addToCart(id, itemData) {
+    if (this.auth.currentUser === null) {
+      throw "Not signed in";
+    }
+    if (this.auth)
     console.log("addToCart", id, JSON.stringify(itemData));
     return this.db
       .collection("carts")