version: 2
#
# Reusable Snippets!
#
# These are re-used by the various tests below, to avoid repetition.
#
run_install_desired_npm: &run_install_desired_npm
  run:
    # Due to a bug, npm upgrades from the version of npm that ships with
    # Node.js 6 (npm v3.10.10) go poorly and generally cause other problems
    # within the environment.  Since `yarn` is already available here we can
    # use that to work-around the issue.  It's possible that `npm` artifact
    # jockeying might avoid this need, but this can be removed once Node 6 is
    # no longer being built below.
    name: Install npm@5, but with yarn.
    command: sudo yarn global add npm@5

# These are the steps used for each version of Node which we're testing
# against.  Thanks to YAMLs inability to merge arrays (though it is able
# to merge objects), every version of Node must use the exact same steps,
# or these steps would need to be repeated in a version of Node that needs
# something different.  Probably best to avoid that, out of principle, though.
common_test_steps: &common_test_steps
  steps:
    # Install the latest npm, rather than using the versions which ship
    # in older versions of Node.js  This allows for a more consistent
    # installation, and typically users of older Node versions at least
    # update their npm to the latest.
    - *run_install_desired_npm

    - checkout

    # Build a cache key which will bust with Node.js ABI and version changes.
    - run: |
        node -p process.config | tee .cache_key
        node -p process.versions | tee -a .cache_key
        cat package-lock.json | tee -a .cache_key

    - restore_cache:
        keys:
          - v1-dependencies-{{ checksum ".cache_key" }}

    - run: node --version

    - run: npm --version

    - run: npm install

    - save_cache:
        paths:
          - node_modules
        key: v1-dependencies-{{ checksum ".cache_key" }}

    # test with coverage.
    - run: npm run circle


jobs:
  # Platform tests, each with the same tests but different platform or version.
  # The docker tag represents the Node.js version and the full list is available
  # at https://hub.docker.com/r/circleci/node/.
  Node.js 4:
    docker: [ { image: 'circleci/node:4' } ]
    <<: *common_test_steps

  Node.js 6:
    docker: [ { image: 'circleci/node:6' } ]
    <<: *common_test_steps

  Node.js 8:
    docker: [ { image: 'circleci/node:8' } ]
    <<: *common_test_steps

  Node.js 10:
    docker: [ { image: 'circleci/node:10' } ]
    <<: *common_test_steps

  # Linting can run on the latest Node, which already has the latest `npm` and
  # doesn't warrant run_install_desired_npm (which is more critical above)
  Linting:
    docker: [ { image: 'circleci/node:8' } ]
    steps:
      # (speed) Intentionally omitted (unnecessary) run_install_desired_npm.
      - checkout
      - run: npm install
      - run: npm run lint

workflows:
  version: 2
  Build and Test:
    jobs:
      # There isn't any non-generated code in this package now, so we only
      # bother to run one test job and no linting.
      - Node.js 10