Since the Article fetcher is now Promise based - and Promisekit is Swift, you can not write any tests for it in Obj-C. They must be swift tests. So these test need rewritten.
See Xcode 6 release notes:
"XCTest test classes written in Objective-C cannot import the Swift generated interfaces header ($(PRODUCT_MODULE_NAME)-Swift.h) for application targets, and cannot be used to test code that requires this header."