Open Radar

 
Summary:
Registering an implementation of the XCTestObservation protocol with [[XCTestObservationCenter sharedTestObservationCenter] addTestObserver:] causes XCTest to not output the progress of nor the summary of a test run.

Steps to Reproduce:
1. Clone the example project from https://github.com/phatblat/XCTestObserver

2. Open the .xcodeproj
3. Open the Console pane (View -> Debug Area -> Activate Console)
4. Ensure the console output is visible by selecting the "Show the Console" button in the bottom right-hand corner
5. Run the tests (Product -> Test)
6. Console output will only include a few lines
 - https://raw.githubusercontent.com/phatblat/XCTestObserver/master/test_output1.log

7. Open the TestObserver.m file in the Xcode editor
8. Comment out line 16 which adds the test observer
9. Run the tests (Product -> Test)
10.  Console output will include standard XCTest output with summary of the test run
 - https://raw.githubusercontent.com/phatblat/XCTestObserver/master/test_output2.log

Expected Results:
The console output in step 6 will be the same (aside from timestamps) as in step 10.

Actual Results:
The console output in step 6 is missing all output from the XCTest framework.

Regression:
I do not believe this issue was not present in Xcode 7.2.1.

Notes:
The XCTest output is used by several tools (xctool) to monitor test progress and report pass/fail. Without the XCTest output these tools cannot perform this function.

The Nimble framework (https://github.com/Quick/Nimble) uses this XCTestObservation API to monitor test progress and to recordFailureWithDescription through the current XCTestCase.
https://github.com/Quick/Nimble/blob/master/Sources/Nimble/Adapters/NimbleXCTestHandler.swift#L40-L52

When a test suite using Nimble is executed through xctool, it either stalls or crashes waiting for this output.

Version & Build:
Xcode 7.3 (7D175),
Swift Toolchain: Xcode 7.3 Default
OS X 10.11.4 (15E65)