name: tests

on:
  push:
  pull_request:

jobs:
  test:
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        # The game targets Node >=20 (see package.json engines); run the suite on
        # the current LTS lines so a version-specific regression can't slip through.
        node-version: [20, 22]
    name: tests (node ${{ matrix.node-version }})
    steps:
      - uses: actions/checkout@v5
      - uses: actions/setup-node@v5
        with:
          node-version: ${{ matrix.node-version }}
      # No dependencies to install — the game and its test suite run on the Node
      # standard library alone, which is the whole point. Just run the tests.
      - name: Run the engine test suite
        run: npm test
      # CONTRIBUTING.md's release checklist requires `npm run typecheck` (tsc -p jsconfig.json)
      # to pass, but no CI step ever ran it. TypeScript stays out of package.json — this repo is
      # explicitly "No dependencies, no build step" — so fetch the compiler on-demand via npx
      # instead of installing it. `--package typescript` names the package explicitly so this
      # works correctly on a clean runner regardless of any ambient global `tsc`, unlike a bare
      # `npx tsc` (which depends on npx's registry-matching behavior).
      #
      # THE VERSION IS PINNED, and that part is load-bearing. Unpinned, `--package typescript`
      # resolves to whatever is newest on the registry that morning, so a green commit can go red
      # overnight with no code change and a real regression is indistinguishable from a compiler
      # upgrade. That is not hypothetical here: TypeScript 7 reported 21 errors on a tree that
      # TypeScript 5.7 reported 2 on, and CI stayed red across two merges to main. Pinning the
      # INVOCATION keeps the compiler out of package.json exactly as the note above intends —
      # it is still not a dependency, it is just no longer a moving target. Bump this
      # deliberately, in its own commit, so a compiler upgrade is reviewable on its own.
      - name: Type-check the annotated files
        run: npx --yes --package typescript@5.7.2 -- tsc -p jsconfig.json

  # The suite above is headless and dependency-free, which is the whole point of it — and it means
  # nothing in it can see a page that parses, imports cleanly, and then throws on load. With no
  # build step that failure is a blank white screen, and the way it has been caught here before is
  # a human opening index.html. Demonstrated: a bad draw call in renderUnits.js leaves all 2502
  # tests passing and takes the game down on the first frame.
  #
  # So: one job that boots the real page in real Chromium, starts a match, clicks, and fails on any
  # uncaught error. Playwright is fetched at run time via npx and never enters package.json —
  # exactly the precedent the type-check step set for TypeScript. It is a separate job rather than
  # a matrix step because it tests the BROWSER, not the Node version; running it twice would just
  # cost two Chromium downloads to learn the same thing.
  smoke:
    runs-on: ubuntu-latest
    name: browser smoke test
    steps:
      - uses: actions/checkout@v5
      - uses: actions/setup-node@v5
        with:
          node-version: 22
      # --no-save: Playwright is installed for this checkout only and never enters package.json,
      # so the repo keeps its zero-dependency promise. `npx --package playwright -- node ...` is
      # the tidier-looking version of this and does NOT work — npx puts the package's BIN on PATH
      # but not its module on a child node process's resolution path, so the script's own require
      # fails. That shipped broken once; this is the verified form.
      #
      # The FULL playwright package, not playwright-core: only the full one carries the CLI that
      # downloads browsers. Pinned for the same reason the compiler is — a gate that moves
      # underneath you cannot tell a regression from an upgrade. Chromium only; the bare
      # `playwright install` pulls three browsers this never launches.
      - name: Install Playwright and Chromium (never saved to package.json)
        run: |
          npm install --no-save playwright@1.56.1
          npx playwright install --with-deps chromium
      - name: Boot the game in a real browser
        run: npm run smoke