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 causes other problems
    # with the environment.  Since yarn is already available here we can just
    # use that to work-around the issue.  It's possible that npm cleanup might
    # prevent this from being necessary, 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:
    - *run_install_desired_npm
    - checkout
    - run: npm --version
    - run: npm install
    - run: npm run travis

# Important! When adding a new job to `jobs`, make sure to define when it
# executes by also adding it to the `workflows` section below!
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 6:
    docker: [ { image: 'circleci/node:6' } ]
    <<: *common_test_steps

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

  Node.js 9:
    docker: [ { image: 'circleci/node:9' } ]
    <<: *common_test_steps

  # Other tests, unrelated to typical code tests.
  Linting:
    docker: [ { image: 'circleci/node:8' } ]
    steps:
      # (speed) Intentionally omitted, unnecessary, run_install_desired_npm.
      - checkout
      # (speed) --ignore-scripts to skip unnecessary Lerna build during linting.
      - run: npm install --ignore-scripts
      - run: npm run lint
  Docs:
    docker: [ { image: 'circleci/node:8' } ]
    steps:
      # (speed) Intentionally omitted, unnecessary, run_install_desired_npm.
      - checkout
      # (speed) Ignore scripts to skip the Lerna build stuff for linting.
      - run: npm install-test --prefix ./docs

ignore_doc_branches: &ignore_doc_branches
  filters:
    branches:
      # If 'docs' is found, with word boundaries on either side, skip.
      ignore: /.*?\bdocs\b.*/

workflows:
  version: 2
  Build and Test:
    jobs:
      - Node.js 6:
          <<: *ignore_doc_branches
      - Node.js 8:
          <<: *ignore_doc_branches
      - Node.js 9:
          <<: *ignore_doc_branches
      - Linting:
          <<: *ignore_doc_branches
      - Docs