Xcode 5: Unit Tests not running
For me worked changing "Wrapper extension" from "octest" to "xctest" in Build Settings for tests target
Xcode 5 now used XCTestCase, not SenTest. Apple is now supporting Unit Testing more directly including their own version of SenTest named XCTestCase. Additionally the UI is much improved, allowing individual tests to be run, a Test Navigator and no longer creating .h test files. Note that the test macros are not renames with an XC prefix.
See the WWDC-13 video 409: "Testing in Xcode 5".
If you use the Xcode 5 template to create the testing environment the project will include a test target and a working (and failing) test.
If you are creating a new test target in Xcode 5+ and planning to use SenTestKit for unit tests, changing the 'Wrapper Extension' build setting of your test target to 'octest' from the default 'xctest' will help execute the test cases.