ci.yaml

name: CI

# Controls when the action will run.
on:
  # Triggers the workflow on push or pull request events but only for the main branch
  push:
    branches: [main]
  pull_request:
    branches: [main]

  # Allows you to call this workflow from another workflow
  workflow_call:

  # Allows you to run this workflow manually from the Actions tab
  workflow_dispatch:

concurrency:
  # Cancel previous actions from the same PR: https://stackoverflow.com/a/72408109
  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
  cancel-in-progress: true

jobs:
  # matrix-prep-* steps generate JSON used to create a dynamic actions matrix.
  # Insanely complex for how simple this requirement is inspired from
  # https://stackoverflow.com/questions/65384420/how-to-make-a-github-action-matrix-element-conditional

  matrix-prep-bazelversion:
    # Prepares the 'bazelversion' axis of the test matrix
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - id: versions_from_bazel_versions_bzl
        run: echo "bazelversions=$(.github/workflows/bazel_versions.py)" >> $GITHUB_OUTPUT
    outputs:
      # Will look like ["<version from .bazelversion>","<version from bazel_versions.bzl>"]
      bazelversions: ${{ steps.versions_from_bazel_versions_bzl.outputs.bazelversions }}

  test:
    # The type of runner that the job will run on
    runs-on: ${{ matrix.os }}

    needs:
      - matrix-prep-bazelversion

    # Run bazel test in each workspace with each version of Bazel supported
    strategy:
      fail-fast: false
      matrix:
        os: [ubuntu-latest, macos-latest]
        bazelversion: ${{ fromJSON(needs.matrix-prep-bazelversion.outputs.bazelversions) }}
        bzlmodEnabled: [true, false]
        folder:
          - "."
          - "e2e/workspace"
        target: ["//..."]
        include:
          - os: ubuntu-latest
            bazelversion: ${{ fromJSON(needs.matrix-prep-bazelversion.outputs.bazelversions)[0] }}
            bzlmodEnabled: false
            folder: "."
            target: "//zig/tests/integration_tests"
          - os: ubuntu-latest
            bazelversion: ${{ fromJSON(needs.matrix-prep-bazelversion.outputs.bazelversions)[0] }}
            bzlmodEnabled: true
            folder: "."
            target: "//zig/tests/integration_tests"
          - os: macos-latest
            bazelversion: ${{ fromJSON(needs.matrix-prep-bazelversion.outputs.bazelversions)[0] }}
            bzlmodEnabled: true
            folder: "."
            target: "//zig/tests/integration_tests"
        exclude:
          # Don't test bzlmod with Bazel 5 (not supported)
          - bazelversion: 5.3.2
            bzlmodEnabled: true
          # Only test the latest Bazel version on MacOS (MacOS runners are expensive and slow)
          - bazelversion: 5.3.2
            os: macos-latest

    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
      - uses: actions/checkout@v3

      # Cache build and external artifacts so that the next ci build is incremental.
      # Because github action caches cannot be updated after a build, we need to
      # store the contents of each build in a unique cache key, then fall back to loading
      # it on the next ci run. We use hashFiles(...) in the key and restore-keys- with
      # the prefix to load the most recent cache for the branch on a cache miss. You
      # should customize the contents of hashFiles to capture any bazel input sources,
      # although this doesn't need to be perfect. If none of the input sources change
      # then a cache hit will load an existing cache and bazel won't have to do any work.
      # In the case of a cache miss, you want the fallback cache to contain most of the
      # previously built artifacts to minimize build time. The more precise you are with
      # hashFiles sources the less work bazel will have to do.
      - name: Mount bazel caches
        uses: actions/cache@v3
        with:
          path: |
            ~/.cache/bazel
            ~/.cache/bazel-repo
          key: bazel-cache-${{ matrix.os }}-${{ matrix.bazelversion }}-${{ matrix.bzlmodEnabled }}-${{ matrix.folder }}-${{ matrix.target }}-${{ hashFiles('**/BUILD.bazel', '**/*.bzl', '**/*.zig', 'WORKSPACE', 'WORKSPACE.bzlmod', 'MODULE.bazel') }}
          restore-keys: |
            bazel-cache-${{ matrix.os }}-${{ matrix.bazelversion }}-${{ matrix.bzlmodEnabled }}-${{ matrix.folder }}-${{ matrix.target }}

      - name: Configure Bazel version
        working-directory: ${{ matrix.folder }}
        run: echo "USE_BAZEL_VERSION=${{ matrix.bazelversion }}" > .bazeliskrc

      - name: Test generated files
        if: matrix.folder == '.' && matrix.target == '//...'
        env:
          # Bazelisk will download bazel to here, ensure it is cached between runs.
          XDG_CACHE_HOME: ~/.cache/bazel-repo
        run: |
          bazel --bazelrc=$GITHUB_WORKSPACE/.github/workflows/ci.bazelrc --bazelrc=.bazelrc run //util:update
          test -z $(git status --porcelain) || { echo "Update generated files using `bazel run //util:update`" >&2; git diff >&2; exit 1; }

      - name: Check for test.sh
        # Checks for the existence of test.sh in the folder. Downstream steps can use
        # steps.has_test_sh.outputs.files_exists as a conditional.
        id: has_test_sh
        uses: andstor/file-existence-action@v2
        with:
          files: "${{ matrix.folder }}/test.sh"

      - name: Set bzlmod flag
        # Store the --enable_bzlmod flag that we add to the test command below
        # only when we're running bzlmod in our test matrix.
        id: set_bzlmod_flag
        if: matrix.bzlmodEnabled
        run: echo "bzlmod_flag=--enable_bzlmod" >> $GITHUB_OUTPUT

      - name: bazel test ${{ matrix.target }}
        env:
          # Bazelisk will download bazel to here, ensure it is cached between runs.
          XDG_CACHE_HOME: ~/.cache/bazel-repo
        working-directory: ${{ matrix.folder }}
        run: bazel --bazelrc=$GITHUB_WORKSPACE/.github/workflows/ci.bazelrc --bazelrc=.bazelrc test ${{ steps.set_bzlmod_flag.outputs.bzlmod_flag }} ${{ matrix.target }}

      - name: ./test.sh
        # Run if there is a test.sh file in the folder
        if: steps.has_test_sh.outputs.files_exists == 'true'
        working-directory: ${{ matrix.folder }}
        shell: bash
        # Run the script potentially setting BZLMOD_FLAG=--enable_bzlmod. All test.sh
        # scripts that run bazel directly should make use of this variable.
        run: BZLMOD_FLAG=${{ steps.set_bzlmod_flag.outputs.bzlmod_flag }} ./test.sh