I'm trying to add some unit tests to an existing code base using Visual Studio 2010's unit test generator. However, in some cases when I open a class, right click --> Create Unit Tests..., after I select the methods to generate tests for it will create what is essentially a blank test. Are there situations where this can happen? In every case I select at least one public method to gen tests for, and all it generates is this:

```
using TxRP.Controllers; //The location of the code to be tested
using Microsoft.VisualStudio.TestTools.UnitTesting;

```

That's it. Nothing else. Strange, right? 

I should note that this is all MVC 2 controller code, and I have been able to gen tests for other controllers with no problem, and all my controllers follow pretty much the same format. ~~No error seems to be thrown, as it gens the empty page happily and adds it to the project as if everything is just fine.~~

Has anyone had experience with the same type of thing happening, and was there any answer found as to why?

**UPDATE:** 
There is in fact an error during generation:

> 
> 
> ```
> While trying to generate your tests, the following errors occurred:
> Value cannot be null.
> Parameter name: key
> 
> ```
> 
> 

After some research, the only possible solution I found is that this error occurrs if you're trying to generate tests to a test file that already exists. However, this solution is not working for me...