[raiseCatError]

CoalescingFetchTests.testAnInvalidationDuringARequestWaitsForTheNextOne failed on #141's Mac job (run 41663143761): XCTAssertEqual failed: ("2") is not equal to ("1") at line 61. #141 only edits a workflow, so the failure is unrelated to it.

Root cause: an ordering assumption in the test, not an app bug

• The stand-in service numbers answers by the order requests start, and the test slept 50 ms and relied on request 1 also answering first.
• On a stalled runner (the test took 2.4 s instead of ~0.25 s), request 2 answered first. CoalescingFetch then correctly served both waiters from request 2, a request started after the invalidation, so first == 2. The late caller still got 2, and only 2 requests were sent.
• Reproduced with the unchanged code and test body in a standalone build: 1 of about 2,000 runs, on a cold first launch, with exactly first=2 late=2 calls=2. A gated service that releases request 2 first gives the same result every time.
• Same class as the earlier timing failures in this file (testNoMoreThanTwoRequestsAreOut, testStartedAfterNowGetsANewRequestSharedByLateCallers).

Change (test only)

• A GatedService stand-in answers each request only when the test releases it, so the order is fixed by the test, not by the scheduler. Its only waits are condition polls ("request n is out"), not timing assumptions.
• The original test keeps every assertion, with requests answering in order.
• New …WhenAnswersArriveOutOfOrder: request 2 answers first. Both callers get 2, the late caller never gets the stale answer, and 2 requests are sent.
• No app code, assertion or timeout is loosened, and no test is skipped.

Checked locally (Xcode builds blocked by low internal disk; the real test file was compiled with swiftc against XCTest):

• All 12 CoalescingFetchTests pass.
• The two changed tests ran 1,600 times with no failures (1,000 idle, 600 under full CPU load).
• A mutant that serves the stale answer to every waiter fails the test.

The mac job here is the first full Xcode run of the change.

🤖 Generated with Claude Code