test: make path assertions platform-agnostic so the suite passes on Windows - #1450

Summary

Five tests across two suites fail on Windows because they compare platform-native paths against hard-coded POSIX literals, so pnpm test is red even though the code under test is correct:

● HermesBytecodePlugin › getHermesCLIPath › returns new hermes-compiler path when it exists

  Expected: "path/to/hermes-compiler/hermesc/osx-bin/hermesc"
  Received: "path\to\hermes-compiler\hermesc\osx-bin\hermesc"

getHermesCLIPath and resolveProjectPath build those paths with path.join / path.resolve, which is exactly what they should do — the separators are right for the platform. It's the expectations that are POSIX-only.

The fix runs the expectations through path.join / path.resolve rather than comparing raw strings. Both are no-ops on POSIX, so Linux and macOS runs are byte-for-byte unchanged; the literals stay readable as POSIX in the source.

One case needed a bit more

In resolveProjectPath.test.ts the root is resolved as well, not just the expectation. With a POSIX root and no drive letter, up-level navigation that reaches the root collapses to a bare \, and Windows then reads \ + /shared/... as the start of a UNC share:

● should resolve [projectRoot^N] prefix with up-level navigation

  Expected: "C:\shared\utils.js"
  Received: "\\shared\utils.js\\"     ← \shared\utils.js\ , a network path

Resolving the root first gives it a drive letter, so path.join keeps the drive when it walks up and the result stays local. To be clear about scope: I don't think this is reachable in production, because rootDir there comes from a real project directory and always carries a drive on Windows. It's a property of feeding the function a POSIX absolute path on Windows, so I've fixed it in the test and left resolveProjectPath alone. Flagging it because the failure mode is a surprising one and worth knowing about.

Test plan

Windows 11, Node 22.23.2, pnpm 10.34.5.

Before — @callstack/repack:

Test Suites: 2 failed, 31 passed, 33 total
Tests:       5 failed, 294 passed, 299 total

After:

Test Suites: 33 passed, 33 total
Tests:       299 passed, 299 total

pnpm lint (biome) is clean. metro-compat-test (47 passed), resolver-cases-test (3 files) and repack-dev-server (5 tests) all pass on Windows both before and after.

Not addressed here: tests/integration fails on Windows with Module build failed — 4 files, 50 tests, 24 snapshots. I verified this is pre-existing and unrelated by stashing my changes and re-running on a clean tree, which produced the identical 50 failed | 8 passed. It looks like a separate Windows issue and I didn't want to bundle a fix for it into this PR. Happy to look into it separately if that'd be useful.

I noticed test-main-matrix.yml already has an os matrix axis, currently [ubuntu-latest]. If you'd like these kept honest, adding windows-latest there would do it — glad to open that as its own PR rather than assume you want the extra CI minutes.