Skip to content

failure-modes.md

Latest commit

 

History

History
30 lines (23 loc) · 2.3 KB

failure-modes.md

File metadata and controls

30 lines (23 loc) · 2.3 KB
Raw

Failure Modes and Snapshot Workflow

Common Failures

Error pattern Likely cause Recovery
Expected image to match or be a close match to snapshot Real visual change or regression Inspect the diff PNG, then decide whether to update snapshots or fix the code
Timeout or hanging Jest run Selenium sessions leaked Run python3 ./.github/skills/webchat-html-tests/scripts/cleanup-grid-sessions.py before rerunning
Failed to load resource: 404 (Not Found) for dist files webchat2 serving stale or empty content docker compose -f docker-compose-wsl2.yml restart webchat2
Cannot read properties of undefined (reading 'FluentThemeProvider') Fluent bundle returned 404 Restart webchat2 and confirm the local build completed
Cannot read properties of undefined (reading 'ReactWebChat') Main bundle returned 404 Restart webchat2 and confirm the local build completed

Snapshot Update Flow

  1. Reproduce the failure without --update.
  2. Inspect the generated .snap-N-diff.png file next to the HTML test.
  3. Only if the change is intentional, rerun with --update.
  4. Rerun the same test again without --update to confirm the snapshot is now stable.
  5. Clean leaked Selenium sessions between runs.

HTML Test Anatomy

Most HTML tests follow this structure:

  • Load /test-harness.js and /test-page-object.js
  • Create a Direct Line emulator with testHelpers.createDirectLineEmulator()
  • Drive activities with emulateIncomingActivity() or emulateOutgoingActivity()
  • Assert through pageConditions and pageElements
  • Capture snapshots with await host.snapshot('local')
  • Use expect, not assert