what's the namespace for [datasource] for data driven test

I am adding data driven into my coded UI test. Based on some information online, I should use [DataSource...] before my test method. While, my VS complain don't know this. I was tried to add

Microsoft.VisualStudio.TestTools.UITesting.WinControls namespace, while it complains that WinControls is not under UITesting. How should I make it work?