wasm.yml

name: WasmJS CI

# Two jobs, because the runner can do one of these two things unconditionally and the other only
# when it has been given an interpreter.
#
# The single job this replaces asked for `wasmJsNodeTest` on a runner with no CPython Emscripten
# build. Every wasm task is guarded by `onlyIf { <that build>.exists() }`, so the task SKIPped and
# the job reported **green having run zero tests** -- a tick that measured nothing, which is worse
# than a red one because nobody goes looking. See `wasmRuntimePresent` in
# python-multiplatform/build.gradle.kts.
#
# `compile` is what a runner can always do honestly, and it is named for exactly that.
# `test` runs the real suite, and runs only when there is a runtime to run it against.

on:
  push:
    branches: [ "develop", "main" ]
  pull_request:
    branches: [ "develop", "main" ]

concurrency:
  # A newer push to the same ref supersedes this run; frees the shared macOS runners.
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  compile:
    name: WasmJS compile (no interpreter)
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Setup Java
        uses: actions/setup-java@v4
        with:
          java-version: '21'
          distribution: 'zulu'
          cache: 'gradle'

      - name: Setup Node
        uses: actions/setup-node@v4
        with:
          node-version: '20'

      - name: Cache Konan
        uses: actions/cache@v4
        with:
          path: ~/.konan
          key: ${{ runner.os }}-konan-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
          restore-keys: |
            ${{ runner.os }}-konan-

      # No test task here, deliberately. Compiling `wasmJsMain` and `wasmJsTest` needs no
      # interpreter, so this is coverage the runner can actually deliver; asking for a test task it
      # cannot run is what produced the empty green tick.
      - name: Compile wasmJs main and test sources
        run: ./gradlew :python-multiplatform:compileKotlinWasmJs :python-multiplatform:wasmJsTestClasses --console=plain

      # Says out loud what the green tick above does and does not cover, so that a reader of this
      # workflow's result does not have to infer it. Drops away the moment the runtime URL exists.
      - name: Say what did not run
        if: vars.WASM_RUNTIME_URL == ''
        run: |
          {
            echo "### wasmJs tests did not run"
            echo
            echo "This job compiled \`wasmJsMain\` and \`wasmJsTest\`. **No wasm test was executed.**"
            echo
            echo "Running them needs a CPython Emscripten build, which this repository publishes as"
            echo "\`io.github.thisisthepy:python-multiplatform-wasm-runtime\` (a 7 MB zip built by"
            echo "\`:python-multiplatform:wasmBrowserRuntimeZip\`) but has never pushed to a remote"
            echo "repository -- it exists only in the maintainer's \`mavenLocal\`."
            echo
            echo "Set the repository variable \`WASM_RUNTIME_URL\` to a URL that serves that zip"
            echo "(a GitHub release asset is enough) and the \`test\` job below will run the real"
            echo "suite: 344 Node tests and 10 browser tests."
          } >> "$GITHUB_STEP_SUMMARY"
          echo "::warning title=wasmJs tests did not run::No CPython Emscripten runtime is available to this runner; set the WASM_RUNTIME_URL repository variable. This job compiled only."

  test:
    name: WasmJS Node + browser tests
    runs-on: ubuntu-latest
    # The whole point of the guard: this job exists only when it can do its job. A job that does not
    # run shows up grey in the checks list, which is a different claim from a green one.
    if: vars.WASM_RUNTIME_URL != ''
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Setup Java
        uses: actions/setup-java@v4
        with:
          java-version: '21'
          distribution: 'zulu'
          cache: 'gradle'

      - name: Setup Node
        uses: actions/setup-node@v4
        with:
          node-version: '20'

      - name: Cache Konan
        uses: actions/cache@v4
        with:
          path: ~/.konan
          key: ${{ runner.os }}-konan-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
          restore-keys: |
            ${{ runner.os }}-konan-

      # The five files this unpacks are the whole interpreter as far as the test tasks are
      # concerned -- python.wasm, python.mjs, the stdlib zip and the two glue modules. That is a
      # property of `cpython.mjs`'s boot rather than an accident: the Node route used to reach the
      # standard library through NODEFS against a CPython *source checkout*, which no artefact
      # carries, and now installs the staged zip into MEMFS exactly as the browser route does.
      - name: Fetch the CPython Emscripten runtime
        run: |
          set -euo pipefail
          curl -fsSL "${{ vars.WASM_RUNTIME_URL }}" -o "$RUNNER_TEMP/wasm-runtime.zip"
          mkdir -p "$RUNNER_TEMP/wasm-runtime"
          unzip -q "$RUNNER_TEMP/wasm-runtime.zip" -d "$RUNNER_TEMP/wasm-runtime"
          for f in python.wasm python.mjs; do
            test -f "$RUNNER_TEMP/wasm-runtime/$f" \
              || { echo "::error::$f is not in the runtime zip served by WASM_RUNTIME_URL"; exit 1; }
          done
          ls -l "$RUNNER_TEMP/wasm-runtime"

      # `WasmCompiledWheelTest` imports a real compiled pyemscripten_2026_0 wheel. Under
      # `-PrequireWasmRuntime` a missing wheel is a failure, not a skip, so fetch them first: by URL,
      # each accepted only against the sha256 the script pins.
      - name: Fetch the pinned wasm wheels
        run: bash tools/wasm/build-cpython.sh wheels

      # `-PrequireWasmRuntime` is the second half of the guard, and it is what makes this job unable
      # to repeat the original defect: if either task would skip -- no interpreter, or no
      # Chromium-family browser for karma -- the build fails naming what was missing, instead of
      # reporting success having run nothing.
      - name: Run wasmJs tests
        run: |
          ./gradlew \
            :python-multiplatform:wasmJsNodeTest \
            :python-multiplatform:wasmJsBrowserTest \
            -PwasmPythonDir="$RUNNER_TEMP/wasm-runtime" \
            -PrequireWasmRuntime=true \
            --console=plain

      # Belt to the guard's braces, and it guards a different failure: a task that *runs* but
      # reports nothing. A wasm `LinkError` at instantiation takes out the whole module and is
      # reported as zero tests rather than as a failure, which is the shape ROADMAP §10 records for
      # a missing stdlib zip in the browser ("404, zero tests reported").
      #
      # The floors are the baselines ROADMAP §10 records, so they fail when coverage *shrinks* and
      # stay quiet when it grows.
      - name: Assert the suites were not empty
        if: always()
        run: |
          python3 - <<'PY'
          import glob, sys, xml.etree.ElementTree as ET
          floors = {"wasmJsNodeTest": 344, "wasmJsBrowserTest": 10}
          bad = False
          for task, floor in floors.items():
              files = glob.glob(f"python-multiplatform/build/test-results/{task}/*.xml")
              total = sum(int(ET.parse(f).getroot().get("tests", 0)) for f in files)
              print(f"{task}: {total} tests in {len(files)} result files (floor {floor})")
              if total < floor:
                  print(f"::error::{task} reported {total} tests, below its recorded baseline of {floor}")
                  bad = True
          sys.exit(1 if bad else 0)
          PY

      - name: Upload test reports
        if: always()
        uses: actions/upload-artifact@v4
        with:
          name: wasm-test-results
          path: python-multiplatform/build/test-results/
          if-no-files-found: error