public void ReadTransactionsFromFile_Valid_ObserverNeverCalled()
{
var mockObserver = new Moq.Mock<Observer>();
List<Observer> ol = new List<Observer>();
ol.Add(mockObserver.Object);
List<Product> listOfProducts = new List<Product>();
TransactionManager tm = new TransactionManager(ol, listOfProducts);
tm.ReadTransactionsFromFile(new StreamReader(@"C:\Users\vbhujan\Documents\Cart.txt"));
mockObserver.Verify(o => o.update(), Times.Never);
}