Tried to initiate the user's password and put some constraint to it

MCTG/MCTGApp/Program.cs

@@ -14,7 +14,7 @@ foreach (User user in users)
     {
         Console.WriteLine(user.Name);
         Console.WriteLine(user.Priorities[0].ToString());
-    } catch (ArgumentNullException erreurNomVide)
+    } catch (ArgumentException erreurNomVide)
     {
         Console.WriteLine(erreurNomVide.Message);
     }

MCTG/MCTGLib/User.cs

@@ -4,6 +4,7 @@ using System.Collections;
 using System.Collections.ObjectModel;
 using System.Threading.Tasks;
 using System.Runtime.CompilerServices;
+using System.Text.RegularExpressions;
 
 namespace MCTGLib
 {
@@ -15,45 +16,39 @@ namespace MCTGLib
     {
         #region Private Attributes
 
-        private string name;
-        private string surname;
-        private string mail;
-
+        private string name="";
+        private string surname="";
+        private string mail = "";
+        private string picture = "";
+        private string password = "";
+        //private bool isAdmin;
+        private string defaultUserSavePath = "";
+        private List<Priority> priorities;
         #endregion
 
         #region Properties
 
-        private string picture;
-        /// <summary>
-        /// For now, we define the ProfilPict as a string which is "PhotoParDefaut"
-        /// when the value is null.
-        /// </summary>
-        public string ProfilPict
-        {
-            get => picture;
-            set => picture = value;
-          
-        }
         /// <summary>
         /// Property to get Name of users and a setter 
         /// </summary>
-        /// <exception cref="ArgumentNullException" >Setter have Exception which is trigger when Name is null</exception>
+        /// <exception cref="ArgumentException" >Setter have Exception which is trigger when Name is null</exception>
         public string Name
         {
             get { return name; }
-            private set 
+            private set
             {
-                if (string.IsNullOrWhiteSpace(value)) 
+                if (string.IsNullOrWhiteSpace(value))
                 {
-                    throw new ArgumentNullException("Il y a une erreur de Nom d'utilisateur!");
+                    throw new ArgumentException("Impossible d'avoir un champ Nom vide!");
                 }
                 name = value;
             }
         }
+
         /// <summary>
         /// Property to get Surname of users and a setter 
         /// </summary>
-        /// <exception cref="ArgumentNullException" >Setter have Exception which is trigger when Surname is null</exception>
+        /// <exception cref="ArgumentException" >Setter have Exception which is trigger when Surname is null</exception>
         public string Surname
         {
             get { return surname; }
@@ -61,15 +56,16 @@ namespace MCTGLib
             {
                 if (string.IsNullOrWhiteSpace(value))
                 {
-                    throw new ArgumentNullException("Il y a une erreur de Prénom d'utilisateur.");
+                    throw new ArgumentException("Impossible d'avoir un champ Prénom vide!");
                 }
                 surname = value;
             }
         }
+
         /// <summary>
         /// Property to get mail of users and a setter 
         /// </summary>
-        /// <exception cref="ArgumentNullException" >User's mail will serve to log the user. So there's no setter, just an init. User will enter one time his email at his
+        /// <exception cref="ArgumentException" >User's mail will serve to log the user. So there's no setter, just an init. User will enter one time his email at his
         /// account creation.</exception>
         public string Mail
         {
@@ -78,14 +74,46 @@ namespace MCTGLib
             {
                 if (string.IsNullOrWhiteSpace(value))
                 {
-                    throw new ArgumentNullException("Il y a une erreur de Mail d'utilisateur.");
+                    throw new ArgumentException("Impossible d'avoir un champ Email vide!");
                 }
                 mail = value;
             }
         }
+        /// <summary>
+        /// For now, we define the ProfilPict as a string which is "PhotoParDefaut"
+        /// when the value is null.
+        /// </summary>
+        public string ProfilPict
+        {
+            get => picture;
+            set => picture = value;
+          
+        }
 
 
-        private List<Priority> priorities;
+        ///<summary>
+        ///Password property 
+        /// </summary>
+        public string Password
+        {
+            get => password; 
+            private set
+            {
+                string modelPassword =  @"[a-z]*[A-Z]+$" ;
+                if (!string.IsNullOrWhiteSpace(value))
+                {
+                    throw new ArgumentException("Le mot de passe ne doit pas etre vide ");
+                }
+               // if (Regex.IsMatch(value, modelPassword, RegexOptions. )
+            }
+                
+        }
+
+        /// <summary>
+        /// This is the list of priorities specific tu the user. This list is initiate
+        /// by default. User could change it at will.
+        /// </summary>
+        
         public List<Priority> Priorities
         {
             get => priorities;
@@ -109,6 +137,7 @@ namespace MCTGLib
             Name = name;
             Surname = surname;
             Mail = mail;
+            Password = password;
             priorities = new List<Priority> {
                 Priority.Gourmet,
                 Priority.Economic,