[RNE Rewrite] test(cpp): add host GoogleTest suites for the native sources

.github/workflows/ci.yml

@@ -39,3 +39,86 @@ jobs:
 
       - name: Build all packages
         run: yarn workspaces foreach --all --exclude react-native-executorch-bare-resource-fetcher --exclude react-native-executorch-expo-resource-fetcher --exclude react-native-executorch-webrtc --topological-dev run prepare
+
+  native-tests:
+    name: C++ unit tests
+    runs-on: ubuntu-latest
+    # Well clear of a cold run (dependency build ~2 min) but far below the 6 h
+    # default, so a stalled download fails with logs instead of hanging.
+    timeout-minutes: 30
+    defaults:
+      run:
+        working-directory: packages/react-native-executorch
+    env:
+      # The package version on this branch is 0.0.0, which has no GitHub Release,
+      # so point the header download at the libs release that carries a
+      # headers.tar.gz. Keep this in sync with the ExecuTorch version pinned in
+      # scripts/build-native-test-deps.sh — the tests compile against these
+      # headers and link libraries built from that pin.
+      RNET_BASE_URL: https://github.com/software-mansion/react-native-executorch/releases/download/v0.10.0-libs
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+
+      # Only googletest is needed; the other submodules are unrelated to the
+      # host test build.
+      - name: Check out googletest
+        run: git submodule update --init --depth 1 third-party/googletest
+        working-directory: ${{ github.workspace }}
+
+      # download-libs.js is dependency-free, so this job needs node but not a
+      # yarn install.
+      - name: Setup Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version-file: .nvmrc
+
+      # Only the two OpenCV modules the cv extension uses. The `libopencv-dev`
+      # meta-package hard-depends on the viz and contrib modules, which pull VTK,
+      # OpenMPI and ~220 packages — over 50 minutes on a throttled mirror.
+      # OpenCVConfig.cmake ships only in that meta-package, so cpp/tests
+      # falls back to locating the libraries directly.
+      - name: Install build tooling
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends \
+            ninja-build libopencv-core-dev libopencv-imgproc-dev
+        working-directory: ${{ github.workspace }}
+        env:
+          DEBIAN_FRONTEND: noninteractive
+
+      - name: Provision third-party headers
+        run: RNET_HEADERS_ONLY=1 node scripts/download-libs.js
+
+      # Hermes and ExecuTorch are pinned to exact tags, so the cache only misses
+      # when scripts/build-native-test-deps.sh changes those pins.
+      #
+      # Split restore/save rather than actions/cache: the combined action only
+      # saves in a post step when the job succeeds, so a failing test would throw
+      # away the ~9 min dependency build and rebuild it on every retry.
+      - name: Restore native test dependencies
+        id: deps-cache
+        uses: actions/cache/restore@v5
+        with:
+          path: packages/react-native-executorch/.native-test-deps
+          key: ${{ runner.os }}-native-test-deps-${{ hashFiles('packages/react-native-executorch/scripts/build-native-test-deps.sh') }}
+
+      - name: Build native test dependencies
+        if: steps.deps-cache.outputs.cache-hit != 'true'
+        run: scripts/build-native-test-deps.sh
+
+      - name: Save native test dependencies
+        if: steps.deps-cache.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v5
+        with:
+          path: packages/react-native-executorch/.native-test-deps
+          key: ${{ steps.deps-cache.outputs.cache-primary-key }}
+
+      # ~486 KB, pinned to an exact HF revision and checksum-verified. Fetched
+      # as its own step so a Hugging Face outage is an obvious failure rather
+      # than a confusing one inside the test run.
+      - name: Fetch .pte test fixtures
+        run: scripts/fetch-test-fixtures.sh
+
+      - name: Run C++ unit tests
+        run: scripts/run-native-tests.sh

.github/workflows/clang-tidy.yml

@@ -46,8 +46,9 @@ jobs:
           # TODO(#1291, @msluszniak): drop this override once a real versioned
           # release exists. download-libs.js resolves the tag from the package
           # version (v${PACKAGE_VERSION} == v0.0.0), but the placeholder 0.0.0 has
-          # no release; headers.tar.gz currently lives only on the test pre-release.
-          RNET_BASE_URL: https://github.com/software-mansion/react-native-executorch/releases/download/v0.0.0-rewrite-libs-test
+          # no release, so point at a libs release that ships headers.tar.gz.
+          # Keep in sync with the same override in ci.yml's native-tests job.
+          RNET_BASE_URL: https://github.com/software-mansion/react-native-executorch/releases/download/v0.10.0-libs
         run: node scripts/download-libs.js
 
       - name: Run clang-tidy

packages/react-native-executorch/.gitignore

@@ -4,3 +4,13 @@ rne-build-config.json
 
 # Generated by scripts/package-release-artifacts.sh
 dist-artifacts/
+
+# Hermes + ExecuTorch host builds for the C++ tests, produced by
+# scripts/build-native-test-deps.sh
+.native-test-deps
+
+# C++ test build output (scripts/run-native-tests.sh)
+cpp/tests/build/
+
+# .pte fixtures downloaded by scripts/fetch-test-fixtures.sh
+cpp/tests/fixtures/

packages/react-native-executorch/compile_flags.txt

@@ -8,3 +8,9 @@
 -isystemthird-party/include/executorch/extension/llm/tokenizers/third-party/json/include
 -isystemthird-party/include/executorch/extension/llm/tokenizers/third-party/re2
 -isystemthird-party/include/executorch/extension/llm/tokenizers/third-party/abseil-cpp
+-Icpp/tests
+-isystem../../third-party/googletest/googletest/include
+-isystem../../third-party/googletest/googlemock/include
+-isystem.native-test-deps/hermes/src/API
+-isystem.native-test-deps/hermes/src/API/jsi
+-isystem.native-test-deps/hermes/src/public