Run WMFData tests serially to fix global-environment race#5965
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Multiple WMFDataTests suites mutate the shared WMFDataEnvironment.current singleton (mediaWikiService/basicService/stores) in their setUp/init. Swift Testing runs suites in parallel by default, so concurrently running suites could overwrite each other's mocked services mid-test, producing intermittent failures (e.g. WMFWatchlistDataControllerTests failing with .serviceError(unableToPullData) when another suite swapped the global service). Per-suite @suite(.serialized) does not fix this: it only serializes tests within a single suite, not separate suites relative to one another. The race is across suites (and the target mixes Swift Testing structs with XCTest classes), so the reliable, low-churn fix is to disable parallel execution for the whole WMFDataTests target in its test plan. Verified locally: max concurrent Swift Testing tests drops from 7 to 1, and the suite passes green across repeated runs. The suite is small, so the serial-execution time cost is negligible. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Problem
Several
WMFDataTestssuites mutate the sharedWMFDataEnvironment.currentsingleton (mediaWikiService/basicService/ stores) in theirsetUp/init. Swift Testing runs suites in parallel by default, so concurrently-running suites can overwrite each other's mocked services mid-test. This produces intermittent failures — e.g.WMFWatchlistDataControllerTests.fetchWatchlistWithProjectFilterfailing with.serviceError(unableToPullData)when another suite swapped the global service out from under it.Why the obvious fixes don't work
@Suite(.serialized)per suite (already present on several suites) only serializes tests within one suite — separate suites still run in parallel relative to one another. This is a cross-suite race.setUp/tearDownsnapshot-restore can't help either: concurrent suites stomp the shared global regardless of restore..serializedbase suite would require converting the XCTest classes — large, risky churn.Fix
Disable parallel execution for the whole
WMFDataTeststarget in its test plan ("parallelizable": false). This is the documented, framework-correct way to serialize an entire target (confirmed by Swift Testing maintainers that the test-plan parallelization setting gates Swift Testing, not just XCTest).Verification
🤖 Generated with Claude Code