Visual Regression Testing in GitHub Actions

Visual regression testing in CI catches UI breakage before it merges. Every PR gets screenshots compared against baselines automatically.

Setup

Create .github/workflows/visual-tests.yml:

name: Visual Regression Tests
on:
  pull_request:
    types: [opened, synchronize, reopened]

jobs:
  visual-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: las-team/lastest/action@main
        with:
          server-url: ${{ secrets.LASTEST_SERVER_URL }}
          runner-token: ${{ secrets.LASTEST_RUNNER_TOKEN }}
          timeout: 300
          fail-on-changes: false

Smart Run: Test Only What Changed

Lastest's Smart Run analyzes git diffs to run only affected tests:

• Changed Button.tsx? Run tests using that component.
• Changed global.css? Run all tests.
• Changed README.md? Skip visual tests.

Turns a 15-minute suite into a 30-second focused check on most PRs.

PR Comments

Status	Meaning	CI Result
passed	No visual changes	Pass
review_required	Visual changes found	Configurable
blocked	Tests failed to run	Fail
safe_to_merge	Changes reviewed and approved	Pass

Cross-OS Testing

Deploy @lastest/runner on different machines - each registers with your server and picks up test jobs:

npm install -g @lastest/runner
lastest-runner start -t YOUR_TOKEN -s https://lastest.yourcompany.com

Branch Baselines

Main is the source of truth. Feature branches fork from main. Approved baselines merge back when the PR closes.