Ok, so maybe I am the last person on the planet to learn about this new attribute, but oh well. 

Last week a co-worker of mine came across this attribute when doing some research and both of us just kinda looked at each other and smiled.  See, for a long while now we have been saying how it would be nice to be able to test non-public methods from external assemblies without the use reflection.  It appears that Microsot thought that this was important enough to add to the framework (thanks guys) in the form of a simple attribute [InternalsVisibleTo] (MSDN Documentation).  Sorry VB.Net developers, Microsoft is again shunning you guys and this attribute is NOT available to you.... :(

In order to use this attribute you need to add one line of code to your AssemblyInfo.cs class for each external assembly that needs to access internal methods.

[assembly: InternalsVisibleTo( "ShoppingCart.Test" )]
Now, to create a Simple application to test.  For this example I will create a simple ShoppingCart that takes a Shopping Cart item.

private List<ShoppingItem> _listOfShoppingItems = new List< ShoppingItem >(); /// <summary> /// Add the item to the cart, but it must be valid first /// </summary> /// <param name="shoppingItem"></param> public void Add( ShoppingItem shoppingItem ) { if ( IsValidShoppingItemToAdd( shoppingItem ) ) { ListOfShoppingItems.Add( shoppingItem ); } } /// <summary> /// Will check to see if the item is valid /// </summary> /// <param name="shoppingItem">The shopping cart item to check before you do an add</param> /// <returns></returns> internal bool IsValidShoppingItemToAdd( ShoppingItem shoppingItem ) { bool returnFlag; returnFlag = ( shoppingItem.Qty > 0 ) ? true : false; returnFlag = ( shoppingItem.Price > 0 ) ? returnFlag : false; return returnFlag; } /// <summary> /// Holds onto the list of items in the cart /// </summary> private List<ShoppingItem> ListOfShoppingItems { get { return _listOfShoppingItems; } }

Here is the test that allows the testing of the internal method. [TestMethod] public void IsValidShoppingItemToAdd_Test() { InternalsVisibleToTester.ShoppingCart cart = new InternalsVisibleToTester.ShoppingCart(); ShoppingItem item = new ShoppingItem(); item.Sku = "2345648"; item.Qty = 0; item.Price = 50m; cart.IsValidShoppingItemToAdd( item ); }

Now, you can test those internal methods from external assemblies.  Like I said above, maybe I was the last to find this, but I am glad I finally did.

Derik