Merge pull request #10 from sameersbn/fix-9

no-op if item is already starred by the user

handler.go

@@ -58,12 +58,7 @@ func GetStars(w http.ResponseWriter, req *http.Request) {
 	for _, it := range items {
 		it.StargazersCount = len(it.StargazersIDs)
 		if currentUser, err := getCurrentUserID(req); err == nil {
-			for _, id := range it.StargazersIDs {
-				if id == currentUser {
-					it.HasStarred = true
-					break
-				}
-			}
+			it.HasStarred = hasStarred(it, currentUser)
 		}
 	}
 	response.NewDataResponse(items).Write(w)
@@ -114,6 +109,11 @@ func UpdateStar(w http.ResponseWriter, req *http.Request) {
 		// Otherwise we just need to update the database
 		op := "$pull"
 		if params.HasStarred {
+			// no-op if item is already starred by user
+			if hasStarred(&it, uid) {
+				response.NewDataResponse(it).WithCode(http.StatusOK).Write(w)
+				return
+			}
 			op = "$push"
 		}
 
@@ -168,3 +168,13 @@ var getCurrentUserID = func(req *http.Request) (bson.ObjectId, error) {
 	}
 	return "", errors.New("invalid token")
 }
+
+// hasStarred returns true if item is starred by the user
+func hasStarred(it *item, user bson.ObjectId) bool {
+	for _, id := range it.StargazersIDs {
+		if id == user {
+			return true
+		}
+	}
+	return false
+}

handler_test.go

@@ -123,6 +123,25 @@ func TestUpdateStar(t *testing.T) {
 	}
 }
 
+func TestUpdateStarDoesNotDuplicate(t *testing.T) {
+	var m mock.Mock
+	currentUser := bson.NewObjectId()
+	m.On("One", &item{}).Return(nil).Run(func(args mock.Arguments) {
+		*args.Get(0).(*item) = item{ID: "stable/wordpress", StargazersIDs: []bson.ObjectId{currentUser}}
+	})
+	dbSession = testutil.NewMockSession(&m)
+	oldGetCurrentUserID := getCurrentUserID
+	getCurrentUserID = func(_ *http.Request) (bson.ObjectId, error) { return currentUser, nil }
+	defer func() { getCurrentUserID = oldGetCurrentUserID }()
+
+	m.AssertNotCalled(t, "UpdateId")
+	w := httptest.NewRecorder()
+	requestBody := `{"id": "stable/wordpress", "has_starred": true}`
+	req := httptest.NewRequest("PUT", "/v1/stars", bytes.NewBuffer([]byte(requestBody)))
+	UpdateStar(w, req)
+	assert.Equal(t, http.StatusOK, w.Code)
+}
+
 func TestUpdateStarInsertsInexistantItem(t *testing.T) {
 	var m mock.Mock
 	m.On("One", &item{}).Return(errors.New("not found"))