Is the MIT license suitable for an open source library that is only used in unit testing scenarios?

Question

Some time ago I developed a small project for use in unit testing scenario's and published it on Codeplex. Back then I choose the GPL license but I didn't really understand it. Today I changed it to MIT, because it's a much simpler license that I can understand.

I like to be recognized as the copyright holder, but I want everybody to be able to use the library without worrying about license issues. I think MIT covers both, but not 100% sure. 'Virality' is not an issue for this project.

Would this license (MIT) in any way prevent a person to use my library for the unit testing of a closed-source commercial or private project? In this regard, is my recent change to MIT a change for the better?