No such module 'StdlibUnittest'

I've compiled swift source.
I want to run
I get the error No such module 'StdlibUnittest'
How to link the swift build with Xcode project ?
Also, do I have to use this option (--build-swift-stdlib-unittest-extra) and to use StdlibUnittest ?

The swift/utils/build-script has a --test-paths option.

Otherwise, try using swift/utils/run-test instead.

How do I know if StdlibUnittest is built ?