Done

DesignPatternsSolution/Execise.Tests/UnitTests.cs

@@ -10,20 +10,29 @@ public class UnitTests
         [TestMethod]
         public void LibraryShouldBeSingleton()
         {
-            //check that when you create a Library instance second time, 
-            //you get exactly the same instance as for a very first time
+            var lib = Library.getInstance();
+            var rib = Library.getInstance();
+
+            Assert.AreEqual<Library>(lib, rib);
         }
 
         //test that an book was registered successfully by checking the returned Id value is not -1
         [TestMethod]
         public void BookShouldRegister()
         {
+            Book b = new Book("Guy", "title", 1990, 100);
+            var lib = Library.getInstance();
+
+            Assert.AreNotEqual(lib.Register(b), -1);
         }
 
         //test that an customer was registered successfully by checking the returned Id value is not -1
         [TestMethod]
         public void CustomerShouldRegister()
         {
+            Customer c = new Customer("Guy", "777 Broadway Ave");
+            var lib = Library.getInstance();
+            Assert.AreNotEqual(lib.Register(c), -1);
         }
 
         //test that a book can be borrowed
@@ -32,7 +41,11 @@ public void CanBorrowBook()
         {
             //create a borrowable book with available amount more than one. 
             //Run BorrowOne method of the BookBorrowable instance. Check that total amount was reduced by one.
-
-        }       
+            Book b = new Book("Guy", "title", 1990, 100);
+            BookBorrowable bb = new BookBorrowable(b, 10);
+            var x = bb.borrowOne();
+            Assert.AreEqual(bb.numberOfBooksLeft(), 9);
+
+        }
     }
 }

DesignPatternsSolution/Exercise/BookBorrowable.cs

@@ -1,7 +1,24 @@
 namespace Exercise
 {
-    public class BookBorrowable 
+    public class BookBorrowable
     {
-
+        private Book book;
+        private int numberOfBooks = 0;
+        public BookBorrowable(Book b, int amount)
+        {
+            book = b;
+            numberOfBooks = amount;
+        }
+
+        public Book borrowOne()
+        {
+
+            numberOfBooks--;
+            return book;
+        }
+        public int numberOfBooksLeft()
+        {
+            return numberOfBooks;
+        }
     }
 }

DesignPatternsSolution/Exercise/Item.cs

@@ -8,15 +8,25 @@ public Item(int amount, int year)
             ObjType = ObjectType.Item;
             YearCreated = year;
         }
+
     }
 
-    public class Book : Item
+    public class Book : Item, IRegistarable
     {
-        public Book(string author, string title, int year, int amount) : base(amount, year)
+        public Book(string author, string title, int year, int amount)
+            : base(amount, year)
         {
             NameOrTitle = title;
             Author = author;
         }
         public string Author { get; set; }
+
+        public RegisteredObject GetRegistrationInfo()
+        {
+            RegisteredObject x = new RegisteredObject();
+            x.obj = this;
+            return x;
+        }
+
     }
 }

DesignPatternsSolution/Exercise/Library.cs

@@ -2,17 +2,30 @@
 {
     public class Library
     {
+        private BookBorrowable bbook;
+        private int numberOfBooks = 0;
+
+        static Library instance = new Library();
         //implement Singleton to make sure only one library will exist
+        private Library() { }
+
+
+        public static Library getInstance()
+        {
+            return instance;
+        }
 
-
 
         //Implement Register method by utilizing RegistrationRepository (complete missing parts)
-        public int Register()
+        public int Register(IRegistarable obj)
         {
-            // return RegistrationRepository.Register();
+
+
+            return RegistrationRepository.Register(obj);
 
             //dummy, just to compile
-            return 0;
+            //return 0;
         }
+
     }
 }

DesignPatternsSolution/Exercise/Person.cs

@@ -2,7 +2,7 @@
 
 namespace Exercise
 {
-    public class Customer : LibObject
+    public class Customer : LibObject, IRegistarable
     {
         public string Address { get; set; }
         public DateTime RegisteredAt { get; set; }
@@ -19,5 +19,12 @@ public void SetId(int id)
         {
             ObjectId = id;
         }
+
+        public RegisteredObject GetRegistrationInfo()
+        {
+            RegisteredObject x = new RegisteredObject();
+            x.obj = this;
+            return x;
+        }
     }
 }

DesignPatternsSolution/Exercise/Registration.cs

@@ -50,6 +50,7 @@ public class RegisteredObject
         public string Info { get; set; }
         public int Id { get; set; }
         public int AvailableAmount { get; set; }
+        public LibObject obj { get; set; }
 
         public override string ToString()
         {