04 · CI Integration (GitHub Actions)¶

A test suite that only runs on someone's laptop protects nobody. This module wires a Playwright/pytest suite into GitHub Actions so every pull request runs the full suite automatically, with browsers cached, artifacts uploaded on failure, and results visible without anyone needing local setup.

A minimal workflow¶

# .github/workflows/e2e.yml
name: E2E Tests
on:
  pull_request:
  push:
    branches: [main]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-python@v5
        with:
          python-version: "3.12"

      - run: pip install -r requirements.txt

      - run: playwright install --with-deps chromium

      - run: pytest tests/ --junitxml=results.xml

# `playwright install --with-deps` installs both the browser
# binaries AND the OS-level shared libraries (fonts, codecs,
# etc.) Chromium needs to run headless on a bare Ubuntu runner —
# skipping --with-deps is the #1 cause of "works locally, fails
# in CI" for a fresh CI setup

Caching browser binaries between runs¶

Downloading Chromium/Firefox/WebKit on every run wastes minutes. Cache the Playwright browser directory keyed on the installed version:

      - name: Get Playwright version
        id: pw-version
        run: echo "version=$(pip show playwright | grep Version | cut -d' ' -f2)" >> "$GITHUB_OUTPUT"

      - uses: actions/cache@v4
        id: playwright-cache
        with:
          path: ~/.cache/ms-playwright
          key: playwright-${{ runner.os }}-${{ steps.pw-version.outputs.version }}

      - run: playwright install --with-deps chromium
        if: steps.playwright-cache.outputs.cache-hit != 'true'

      - run: playwright install-deps chromium
        if: steps.playwright-cache.outputs.cache-hit == 'true'

# on a cache hit, the browser binary itself is restored from
# cache (skipping the download), but install-deps still runs
# because the cache only holds ~/.cache/ms-playwright, not the
# apt-installed OS libraries the runner image may not persist

Uploading traces and screenshots on failure¶

The whole point of tracing (Level 2/4) is worthless if the trace file disappears when the CI job ends. Upload it as a build artifact:

      - run: pytest tests/ --tracing=retain-on-failure --screenshot=only-on-failure

      - uses: actions/upload-artifact@v4
        if: failure()
        with:
          name: playwright-traces
          path: test-results/
          retention-days: 7

# `if: failure()` means this step only runs when a prior step
# failed, so passing runs don't waste storage — a teammate can
# download the artifact zip and run
# `playwright show-trace trace.zip` locally, seeing exactly
# what the CI browser saw

Sharding across parallel jobs¶

For suites too large for one runner, split the test IDs across a matrix and merge results, rather than accepting a 40-minute serial run:

jobs:
  test:
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        shard: [1, 2, 3, 4]
    steps:
      - uses: actions/checkout@v4
      - run: pip install -r requirements.txt && playwright install --with-deps chromium
      - run: pytest tests/ --shard=${{ matrix.shard }}/4 --junitxml=results-${{ matrix.shard }}.xml
      - uses: actions/upload-artifact@v4
        with:
          name: results-${{ matrix.shard }}
          path: results-${{ matrix.shard }}.xml

# `--shard=N/M` is provided by pytest-playwright: each of the
# 4 matrix jobs runs a disjoint quarter of the collected tests
# in parallel, cutting a 40-minute suite to roughly 10 minutes
# wall-clock (fail-fast: false so one shard failing doesn't
# cancel the others mid-run)

Required status check on pull requests¶

# repository settings, not YAML — but the practical effect:
# Settings > Branches > Branch protection rule for `main`
#   -> Require status checks to pass before merging
#   -> select the "test" job from e2e.yml

# once configured, GitHub blocks the "Merge" button on any PR
# until this workflow's job reports success — turning "please
# run the tests before merging" into something enforced rather
# than a norm people can forget

Full worked example: complete workflow¶

# .github/workflows/e2e.yml
name: E2E Tests
on:
  pull_request:
  push:
    branches: [main]

jobs:
  test:
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        shard: [1, 2]
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with:
          python-version: "3.12"
      - run: pip install -r requirements.txt
      - uses: actions/cache@v4
        id: pw-cache
        with:
          path: ~/.cache/ms-playwright
          key: playwright-${{ runner.os }}-${{ hashFiles('requirements.txt') }}
      - run: playwright install --with-deps chromium
        if: steps.pw-cache.outputs.cache-hit != 'true'
      - run: playwright install-deps chromium
        if: steps.pw-cache.outputs.cache-hit == 'true'
      - run: >
          pytest tests/ --shard=${{ matrix.shard }}/2
          --tracing=retain-on-failure
          --junitxml=results-${{ matrix.shard }}.xml
      - uses: actions/upload-artifact@v4
        if: failure()
        with:
          name: traces-shard-${{ matrix.shard }}
          path: test-results/

How It Actually Works¶

playwright install --with-deps is really two independent operations happening back to back: playwright install downloads the pinned browser build (Level 1 Module 2) into ~/.cache/ms-playwright, while --with-deps additionally shells out to the runner's package manager (apt-get on Ubuntu images) to install the shared libraries — font rendering libraries, GTK/NSS/audio codecs — that a headless Linux Chromium process needs just to start up and produce correct output, since a bare CI container image typically ships none of them. Caching ~/.cache/ms-playwright skips the download but not the apt-get step, which is exactly why the workflow still runs install-deps separately on a cache hit — the OS package manager state isn't part of what gets cached.

--shard=N/M doesn't change how any individual test runs — it operates purely at pytest's collection phase, partitioning the already-collected list of test items into M disjoint groups (typically by simple index modulo, similar to the hand-rolled sharder in Level 2 Module 6) before any browser is launched. Each shard then runs its own completely independent Playwright session — separate driver process, separate browser process — which is why fail-fast: false matters for sharded CI: one shard's browser crashing or one shard's assertion failing has zero effect on the CDP sessions running in the other matrix jobs, since they share nothing beyond the git checkout.

GitHub & Git — 04 · GitHub Actions Basics (a simple CI workflow)

Exercise¶

Add a GitHub Actions workflow to a real (or sample) repository that installs dependencies, installs Chromium with --with-deps, and runs pytest.
Add browser-binary caching keyed on the Playwright version and confirm a second run shows a cache hit in the Actions log.
Add --tracing=retain-on-failure and an upload-artifact step gated on if: failure(); deliberately break a test, push, and download the resulting trace artifact to open locally with playwright show-trace.
Split the suite across a 2-job shard matrix using --shard=N/M and confirm both shards together still run every test exactly once (compare total test counts before and after sharding).