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CI

The native GPU packages are real dependencies, so tests need a GPU or a software rasterizer. Output comes from a real GPU driver or a software rasterizer, so edges can differ slightly between machines. Use a tolerance such as allowedMismatchedPixelRatio for screenshot baselines shared across machines.

Linux without a GPU​

Install Mesa and force software rendering. WebGL uses Mesa's llvmpipe. WebGPU also needs Mesa's Vulkan driver (lavapipe), which Dawn uses through its Vulkan backend.

sudo apt-get update && sudo apt-get install -y libegl1 libgles2 libgl1-mesa-dri mesa-vulkan-drivers
export LIBGL_ALWAYS_SOFTWARE=1

In GitHub Actions:

.github/workflows/ci.yml
jobs:
  test:
    runs-on: ubuntu-latest
    env:
      LIBGL_ALWAYS_SOFTWARE: '1'
    steps:
      - uses: actions/checkout@v6
      - run: sudo apt-get update && sudo apt-get install -y libegl1 libgles2 libgl1-mesa-dri mesa-vulkan-drivers
      - uses: pnpm/action-setup@v6
      - uses: actions/setup-node@v6
        with:
          node-version: 26
          cache: pnpm
      - run: pnpm install --frozen-lockfile
      - run: pnpm test

This repository's own CI workflow does exactly this, so WebGPU tests run for real, not mocked, on ubuntu-latest on every pull request.

macOS​

macOS uses Metal for both WebGL and WebGPU and needs no setup. CI runs macos-latest.

Windows​

Windows uses Direct3D for both WebGL and WebGPU, with the WARP software adapter on machines without a GPU. CI runs windows-latest.

Versions​

CI runs the suite on Node 22, 24 and 26, and against Vitest 4 and 5.

Keep failure images​

When a screenshot assertion fails, <name>.actual.png and <name>.diff.png are written next to the baseline. Upload them so you can see what the runner rendered:

- uses: actions/upload-artifact@v4
  if: always()
  with:
    name: screenshot-diffs
    path: |
      **/__screenshots__/*.actual.png
      **/__screenshots__/*.diff.png
    if-no-files-found: ignore