Fix failing tests

backend/db.go

@@ -49,11 +49,8 @@ func (db *Db) GetUsers() ([]User, error) {
 func (db *Db) GetUser(id int) (*UserWithAllowance, error) {
 	user := &UserWithAllowance{}
 
-	err := db.db.Query("select u.id, u.name, sum(h.amount) from users u join history h on h.user_id = u.id where u.id = ?").
+	err := db.db.Query("select u.id, u.name, (select ifnull(sum(h.amount), 0) from history h where h.user_id = u.id) from users u where u.id = ?").
 		Bind(id).ScanSingle(&user.ID, &user.Name, &user.Allowance)
-	if errors.Is(err, mysqlite.ErrNoRows) {
-		return nil, nil
-	}
 	if err != nil {
 		return nil, err
 	}

backend/main.go

@@ -62,15 +62,15 @@ func getUser(c *gin.Context) {
 	}
 
 	user, err := db.GetUser(userId)
+	if errors.Is(err, mysqlite.ErrNoRows) {
+		c.JSON(http.StatusNotFound, gin.H{"error": ErrUserNotFound})
+		return
+	}
 	if err != nil {
 		log.Printf("Error getting user: %v", err)
 		c.JSON(http.StatusInternalServerError, gin.H{"error": ErrInternalServerError})
 		return
 	}
-	if user == nil {
-		c.JSON(http.StatusNotFound, gin.H{"error": ErrUserNotFound})
-		return
-	}
 
 	c.IndentedJSON(http.StatusOK, user)
 }
@@ -305,6 +305,17 @@ func postAllowance(c *gin.Context) {
 		return
 	}
 
+	exists, err := db.UserExists(userId)
+	if err != nil {
+		log.Printf(ErrCheckingUserExist, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": ErrInternalServerError})
+		return
+	}
+	if !exists {
+		c.JSON(http.StatusNotFound, gin.H{"error": ErrUserNotFound})
+		return
+	}
+
 	err = db.AddAllowance(userId, &allowanceRequest)
 	if err != nil {
 		log.Printf("Error updating allowance: %v", err)