fix(ios): select an arch when exporting coverage from universal binaries - #6
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llvm-cov cannot read coverage from a universal (multi-arch) Mach-O without -arch, so a simulator build carrying both arm64 and x86_64 slices exported 0% LCOV. This is why consumers building universal simulator binaries (e.g. react-native-firebase) saw an ios-native flag stuck at 0%, while this repo's thin (ONLY_ACTIVE_ARCH=YES) e2e builds were unaffected. ios export/report/summary now: - auto-detect the app binary's slices via 'lipo -archs'; - pass -arch only for fat binaries, choosing the host arch when present else the first slice (thin binaries are unchanged); - accept an override via --arch <arch> or config ios.arch. Adds unit tests for the selection logic and documents the flag.
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Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #6 +/- ##
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+ Coverage 58.85% 59.54% +0.68%
Complexity 15 15
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Files 22 22
Lines 1016 1048 +32
Branches 230 239 +9
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+ Hits 598 624 +26
- Misses 346 352 +6
Partials 72 72
Flags with carried forward coverage won't be shown. Click here to find out more. ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
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Flip the static e2e cell to ONLY_ACTIVE_ARCH=NO so it produces a universal (arm64 + x86_64) simulator binary, exercising the new llvm-cov -arch selection in 'rn-coverage ios export'. If the arch fix regresses, that cell's export drops to 0% and the strict assert fails it — an in-repo regression guard at no extra CI cost (no new cell). The dynamic cell stays thin (ONLY_ACTIVE_ARCH=YES) to keep the primary cell fast. Adds a lipo-based assertion that the static binary is actually multi-arch so the guard can't silently degrade to thin.
Export resolveLlvmArch/buildArchArgs and add tests for detectBinaryArchs (mocked lipo), buildArchArgs, and resolveLlvmArch (override/config/auto) so the new arch-selection lines are covered by unit tests, not only by the universal e2e cell.
The app and WDA builds targeted "-destination id=<udid>", which intermittently fails on GitHub runners with "Unable to find a device matching the provided destination specifier" — a CoreSimulator availability race, even after the booted UDID is ready. A simulator is only needed to install and run (simctl + Appium), never to build for the iphonesimulator SDK, so build with "generic/platform=iOS Simulator" instead. This is the same device-agnostic build Detox uses in RNFB's e2e; the specific UDID is still used for install/launch. Complements the existing 'xcrun simctl list' availability workaround in ci.yml.
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🎉 This PR is included in version 0.2.2 🎉 The release is available on: Your semantic-release bot 📦🚀 |
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Fixes queue item F3: consumers that build universal (multi-arch) iOS simulator binaries — notably react-native-firebase — see their
ios-nativeCodecov flag stuck at 0%, even with full adoption. RNGMA's tooling already documented the limitation:Root cause
llvm-cov(export/show/report) cannot read coverage from a universal Mach-O without an-archselector. A simulator build carrying botharm64andx86_64slices therefore exports empty LCOV.This repo's own e2e never hit the bug because its Xcode Debug build uses the default
ONLY_ACTIVE_ARCH=YES→ a thin binary (which is whye2e-ios-dynamicsits at ~90%). Consumers producing fat simulator binaries hit the 0% path.Fix
ios export,ios report, andios summarynow resolve an architecture before invokingllvm-cov:-archpassed (behavior unchanged).lipo -archs, select the host arch when present, else the first slice.--arch <arch>(CLI) orios.arch(config) always wins.Auto-detection means consumers get the fix for free on upgrade — no config change required. RNFB's
rn-coverage-ios-export.jsalready forwards extra args, so--archis available if they ever want to pin.In-repo dogfood / regression guard (now included)
The static e2e cell now builds with
ONLY_ACTIVE_ARCH=NO, producing a universal (arm64 + x86_64) simulator binary. This exercises the new arch-selection path in CI here: if the fix ever regresses, that cell's export drops to 0% and the strict assert (exit 2) fails the cell. Added alipo-based assertion that the static binary really is multi-arch so the guard can't silently degrade to thin. The dynamic (primary) cell stays thin to keep it fast — no new cell, no extra CI cost.Tests / validation
src/__tests__/arch-selection.test.ts(pure selection logic): thin→none, universal→host, host-absent→first slice, explicit override, blank-ignored. 52 tests / 6 suites pass (was 42/5).yarn typecheck,yarn lint,yarn prepare(build) pass;bash -n+shellcheck -S errorclean on the e2e script.lipo-backeddetectBinaryArchsverified against a real fat binary.npx @docs.page/cli check→ No documentation issues found.Follow-up (not in this PR)
react-native-coveragein RNFB + RNGMA and confirmios-nativeturns non-zero on their Codecov.