[SR-4280] Intermittent timeouts in TestNSNotificationQueue tests

[gparker42]

Previous ID	SR-4280
Radar	None
Original Reporter	@gparker42
Type	Bug
Status	Resolved
Resolution	Done

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug
Assignee	@spevans
Priority	Medium

md5: 5a355daeb4cc3f40d897fa781b2eaad7

Issue Description:

In Swift CI several TestNSNotificationQueue tests have timed out recently.

https://ci.swift.org/job/oss-swift-incremental-RA-linux-ubuntu-16_10/2440
Test Case 'TestNSNotificationQueue.test_defaultQueue' started at 22:33:25.995
TestFoundation/TestNSNotificationQueue.swift:241: error: TestNSNotificationQueue.test_defaultQueue : Asynchronous wait failed - Exceeded timeout of 0.2 seconds, with unfulfilled expectations: Background Execution
Test Case 'TestNSNotificationQueue.test_defaultQueue' failed (1.237 seconds)

https://ci.swift.org/job/swift-PR-Linux-smoke-test/5830
Test Case 'TestNSNotificationQueue.test_postAsapToDefaultQueue' started at 23:31:32.832
TestFoundation/TestNSNotificationQueue.swift:230: error: TestNSNotificationQueue.test_postAsapToDefaultQueue : Asynchronous wait failed - Exceeded timeout of 0.1 seconds, with unfulfilled expectations: Timer
Test Case 'TestNSNotificationQueue.test_postAsapToDefaultQueue' failed (0.243 seconds)

Both failures were using swift-corelibs-foundation 6fd9c1a. I don't know if there are any older failures.

[gparker42]

TestNSNotificationQueue tests temporarily disabled in a30b185.
#921

[spevans]

This has been re-enabled in #2668 and no issues have been seen with this test since.