#50973: ci: split macos-x64 tests into 3 shards (40-x-y)
Manual backport of #50968.
The macos-x64 / test / test (darwin, 1) shard has been hitting the 40-minute step timeout at high rate since 2026-04-06 — see e.g. https://github.com/electron/electron/actions/runs/24181403207 (4 consecutive timeouts on 41-x-y). Successful runs already take ~37-43 min and recent test additions plus the MacWebContentsOcclusion re-enable pushed it past the limit.
This splits macos-x64 (darwin and mas) from 2 shards to 3, matching what linux already does. script/split-tests redistributes 77 spec files from 39+38 → 26+26+25.
Net effect: macos-x64 goes from 4 → 6 test jobs ({darwin,mas} × {1,2,3}). macos-arm64 and Windows stay at 2 shards.
Notes: none
Backport Information
Backported from
#50968: ci: split macos-x64 tests into 3 shardsSemver Impact
Semantic Versioning helps users understand the impact of updates:
- Major (X.y.z): Breaking changes that may require code modifications
- Minor (x.Y.z): New features that maintain backward compatibility
- Patch (x.y.Z): Bug fixes that don't change the API
- None: Changes that don't affect using facing parts of Electron