Xcode 7 UI Tests, Recording button is greyed out

To enable the red button, you have to have the cursor on the test method:

I got stuck on this for a while too. In order to record, you have to be in a class that Xcode recognizes as containing tests. Add a file to your UI testing target with something like:

import Foundation
import XCTest

class MyTests: XCTestCase {
    func testSomething() {

    }
}

Save the file, clean your project, and switch to another file then back to this one. Record button should be available then.