diff --git a/Refactoring/Store.cs b/Refactoring/Store.cs
index d9a7c78..48fcad6 100644
--- a/Refactoring/Store.cs
+++ b/Refactoring/Store.cs
@@ -32,7 +32,7 @@ public void Purchase(string productId, int quantity)
                 throw new OutOfStockException();
             }
 
-            product.Quantity = product.Quantity - quantity+1;
+            product.Quantity = product.Quantity - quantity;
             user.Balance = user.Balance - product.Price * quantity;
 
             dataManager.SaveUser(user);
diff --git a/UnitTestProject/AuthenticatorTests.cs b/UnitTestProject/AuthenticatorTests.cs
new file mode 100644
index 0000000..8b980ae
--- /dev/null
+++ b/UnitTestProject/AuthenticatorTests.cs
@@ -0,0 +1,81 @@
+using Newtonsoft.Json;
+using NUnit.Framework;
+using Refactoring;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace UnitTestProject
+{
+    [TestFixture]
+    class AuthenticatorTests
+    {
+        const string TEST_PRODUCT_ID = "1";
+        private User createTestUser(string name, string password, double balance)
+        {
+            User testUser = new User();
+            testUser.Name = name;
+            testUser.Password = password;
+            testUser.Balance = balance;
+
+            return testUser;
+        }
+
+        [Test]
+        public void Test_ValidUser()
+        {
+
+
+            var users = new List<User>();
+            users.Add(createTestUser("Test User", "Test", 99.99));
+
+            Authenticator authenticator = new Authenticator(users);
+
+            //Act
+            var user = authenticator.Authenticate("Test User", "Test");
+
+            //Assert
+
+            Assert.IsNotNull(user);
+        }
+
+        [Test]
+        public void Test_UserNameInvalid()
+        {
+            
+
+            var users = new List<User>();
+            users.Add(createTestUser("Test User", "Test", 99.99));
+
+             Authenticator authenticator = new Authenticator(users);
+
+            //Act
+             var user = authenticator.Authenticate("Invalid", "Test");
+            
+            //Assert
+            Assert.IsNull(user);
+            
+        }
+
+        [Test]
+        public void Test_UserPasswordInvalid()
+        {
+
+
+            var users = new List<User>();
+            users.Add(createTestUser("Test User", "Test", 99.99));
+
+            Authenticator authenticator = new Authenticator(users);
+
+            //Act
+            var user = authenticator.Authenticate("Test User", "Invalid");
+
+            //Assert
+            Assert.IsNull(user);
+           
+        }
+    }
+}
diff --git a/UnitTestProject/StoreTests.cs b/UnitTestProject/StoreTests.cs
index 9f0b866..a1ae982 100644
--- a/UnitTestProject/StoreTests.cs
+++ b/UnitTestProject/StoreTests.cs
@@ -13,6 +13,7 @@ namespace UnitTestProject
     [TestFixture]
     class StoreTests
     {
+        const string TEST_PRODUCT_ID = "1";
         private User createTestUser(string name, string password, double balance)
         {
             User testUser = new User();
@@ -33,22 +34,29 @@ private Product createTestProduct(string id, string name, double price, int quan
 
             return testProduct;
         }
+        public Store Test_ArrangeSingleProductTest(List<User> users, double value, int inStockQty)
+        {
+        //    const string TEST_PRODUCT_ID = "1";
+
+            var products = new List<Product>();
+            products.Add(createTestProduct(TEST_PRODUCT_ID, "Product", value, inStockQty));
+
+            var dataManager = new DataManager(users, products);
+            var store = new Store(users[0], dataManager);
+            return store;
+        }
 
         [Test]
         public void Test_PurchaseThrowsNoErrorForValidFunds()
         {
             //Arrange
-            const string TEST_PRODUCT_ID = "1";
+        //    const string TEST_PRODUCT_ID = "1";
 
             var users = new List<User>();
             users.Add(createTestUser("Test User", "", 99.99));
 
-            var products = new List<Product>();
-            products.Add(createTestProduct(TEST_PRODUCT_ID, "Product", 9.99, 10));
-
-            var dataManager = new DataManager(users, products);
-            var store = new Store(users[0], dataManager);
-
+            var store = Test_ArrangeSingleProductTest(users, 9.99, 10);
+          
             //Act
             store.Purchase(TEST_PRODUCT_ID, 10);
 
@@ -60,33 +68,68 @@ public void Test_PurchaseThrowsNoErrorForValidFunds()
         public void Test_PurchaseRemovesProductFromStore()
         {
             //Arrange
+         //   const string TEST_PRODUCT_ID = "1";
+
+            var users = new List<User>();
+            users.Add(createTestUser("Test User", "", 99.99));
 
+            var store = Test_ArrangeSingleProductTest(users, 9.99, 10);
+
+   
             //Act
+            store.Purchase(TEST_PRODUCT_ID, 9);
 
             //Assert 
-            //(choose the appropriate statement(s))
-            //Assert.AreEqual(1, products[0].Quantity);
-            //Assert.AreSame(1, products[0].Quantity);
-            //Assert.IsTrue(products[0].Quantity == 1);
+          
+            var product = store.GetProductById(TEST_PRODUCT_ID);
+            Assert.AreEqual(1, product.Quantity);
+        
         }
 
         [Test]
         public void Test_PurchaseThrowsExceptionWhenBalanceIsTooLow()
         {
             //Arrange
+        
+            var users = new List<User>();
+            users.Add(createTestUser("Test User", "", 1.00));
 
-            //Act
+            var store = Test_ArrangeSingleProductTest(users, 1.01, 2);
 
-            //Assert
+
+            Assert.Throws<InsufficientFundsException>(() => store.Purchase(TEST_PRODUCT_ID, 1)); 
+           
         }
 
         [Test]
+        [ExpectedException(typeof(InsufficientFundsException))]
         public void Test_PurchaseThrowsExceptionWhenBalanceIsTooLowVersion2()
         {
             //Arrange
+          
+            var users = new List<User>();
+            users.Add(createTestUser("Test User", "", 1.00));
+
+            var store = Test_ArrangeSingleProductTest(users, 1.01, 2);
 
             //Act
+            store.Purchase(TEST_PRODUCT_ID, 1);
+            //Assert
+        }
 
+        [Test]
+        [ExpectedException(typeof(OutOfStockException))]
+        public void Test_PurchaseThrowsExceptionWhenOutOfStock()
+        {
+        
+            var users = new List<User>();
+            users.Add(createTestUser("Test User", "", 2.00));
+
+            var store = Test_ArrangeSingleProductTest(users, 1.01, 0);
+
+        
+            //Act
+            store.Purchase(TEST_PRODUCT_ID, 1);
             //Assert
         }
 
diff --git a/UnitTestProject/UnitTestProject.csproj b/UnitTestProject/UnitTestProject.csproj
index bcf3847..1a9e337 100644
--- a/UnitTestProject/UnitTestProject.csproj
+++ b/UnitTestProject/UnitTestProject.csproj
@@ -70,6 +70,7 @@
     <Otherwise />
   </Choose>
   <ItemGroup>
+    <Compile Include="AuthenticatorTests.cs" />
     <Compile Include="StoreTests.cs" />
     <Compile Include="IntegrationTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />