ci.yml

name: CI

on:
  push:
    branches: [main]
    paths-ignore:
      - '**.md'
      - 'LICENSE'
      - '.gitignore'
  pull_request:
  workflow_dispatch:

# A newer push to the same branch makes the older run obsolete.
concurrency:
  group: ci-${{ github.ref }}
  cancel-in-progress: true

permissions:
  contents: read

jobs:
  build:
    name: Build and test
    runs-on: ubuntu-latest
    timeout-minutes: 30

    steps:
      - name: Checkout sources
        uses: actions/checkout@v7

      # `cache-jdk` stores the downloaded Temurin package in the runner tool
      # cache, so after the first run the ~200 MB JDK download is skipped.
      # We intentionally do NOT set `cache`, which would cache the Gradle
      # dependency cache a second time under setup-java's own key.
      #
      # 21 matches `java.toolchain` in lib/build.gradle.kts, so the foojay
      # resolver never has to provision a JDK mid-build.
      - name: Setup Java
        uses: actions/setup-java@v6
        with:
          distribution: temurin
          java-version: 21
          cache-jdk: true

      # Caches Gradle itself:
      #   * the distribution downloaded for `gradle-version`,
      #   * wrapper distributions under ~/.gradle/wrapper,
      #   * dependencies and transformed artifacts under ~/.gradle/caches,
      #   * the local build cache and the configuration cache.
      # No extra configuration is needed for any of that. Reads are read-only
      # off the default branch, so pull requests cannot write to the cache.
      #
      # `gradlew` and `gradle/wrapper` are gitignored, so a fresh checkout has
      # no wrapper and `just setup` cannot run without a real `gradle` binary.
      # Supplying gradle-version is what installs that distribution onto the
      # PATH; without it the action assumes a wrapper is already present.
      - name: Setup Gradle
        uses: gradle/actions/setup-gradle@v6
        with:
          gradle-version: '9.2.1'

      # extractions/setup-just installs via @actions/tool-cache, which lands
      # the binary under $RUNNER_TOOL_CACHE/just. Restoring that directory
      # before the setup step lets the action find the tool already present
      # and skip the release download entirely.
      - name: Cache just
        uses: actions/cache@v6
        with:
          path: ${{ runner.tool_cache }}/just
          key: just-${{ runner.os }}-${{ hashFiles('justfile') }}
          restore-keys: |
            just-${{ runner.os }}-

      - name: Setup just
        uses: extractions/setup-just@v4

      - name: Setup gradle wrapper
        run: just setup

      # `just build` runs `./gradlew build`, whose `check` task already runs
      # `spotlessCheck` and the whole test suite, so there is no separate
      # `just test` step. Passing -PtestLogEvents=failed keeps the log to the
      # failures instead of streaming all 321 passing tests.
      - name: Build and test
        run: just build -PtestLogEvents=failed

      - name: Upload test report
        if: always()
        uses: actions/upload-artifact@v7
        with:
          name: test-report-${{ github.run_id }}
          path: lib/build/reports/tests/test
          if-no-files-found: ignore
          retention-days: 7