Migrate from web-test-runner to vitest in browser mode

[Copilot]

Replaces web-test-runner with vitest running tests in browser mode via Playwright/Chromium.

Changes

Test runner configuration

• Add vitest.config.ts with browser mode enabled, Playwright provider, Chromium instance
• Update test script: web-test-runner → vitest run
• Remove web-test-runner.config.js and dependencies (@web/test-runner, @web/dev-server-esbuild)

Test utilities

• Create test/test-utils.ts providing fixture() and html() helpers (replaces @open-wc/testing)
• Create test/setup.ts configuring chai-dom and sinon-chai plugins using vitest's built-in chai
• Update all test imports from @open-wc/testing to ./test-utils.js

TypeScript configuration

• Add types: ["vitest/globals"] for test globals (describe, it, expect, etc.)
• Add skipLibCheck: true to avoid chai type conflicts between vitest and transitive dependencies

Dependencies

• Add: vitest, @vitest/browser, @vitest/browser-playwright, playwright, chai-dom, sinon-chai
• Remove: @web/test-runner, @web/dev-server-esbuild

Example

// test/test-utils.ts
export async function fixture<T extends HTMLElement>(template: string): Promise<T> {
  const container = document.createElement('div')
  container.innerHTML = template.trim()
  const element = container.firstElementChild as T
  document.body.appendChild(element)
  await new Promise(resolve => requestAnimationFrame(resolve))
  return element
}

export function html(strings: TemplateStringsArray, ...values: unknown[]): string {
  return strings.reduce((result, str, i) => result + str + (values[i] ?? ''), '')
}

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• accounts.google.com
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=none --disable-dev-shm-usage --use-angle=swiftshader-webgl --mute-audio --crashpad-handler-pid=3500 --enable-crash-reporter=, --noerrdialogs --user-data-dir=/tmp/puppeteer_dev_chrome_profile-xzu4Tl --change-stack-guard-on-fork=enable --shared-files=v8_context_snapshot_data:100 --field-trial-handle=3,i,1097686444200197014,6574062328990545257,262144 --enable-features=NetworkService,NetworkServiceInProcess --disable-features=BackForwardCache,PaintHolding,Translate --variations-seed-version --trace-process-track-uuid=3190708989122997041 (dns block)
  • Triggering command: /opt/google/chrome/chrome /usr/bin/google-chrome-stable --disable-REDACTED-networking --enable-features=NetworkService,NetworkServiceInProcess --disable-REDACTED-timer-throttling --disable-REDACTEDing-occluded-windows --disable-breakpad --disable-client-side-phishing-detection --disable-component-extensions-with-REDACTED-pages --disable-default-apps --disable-dev-shm-usage --disable-extensions --disable-features=Translate,BackForwardCache --disable-hang-monitor --disable-ipc-flooding-protection --disable-popup-blocking --disable-prompt-on-repost --disable-renderer-REDACTEDing --disable-sync --force-color-profile=srgb --metrics-recording-only (dns block)
• clients2.google.com
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=none --disable-dev-shm-usage --use-angle=swiftshader-webgl --mute-audio --crashpad-handler-pid=3500 --enable-crash-reporter=, --noerrdialogs --user-data-dir=/tmp/puppeteer_dev_chrome_profile-xzu4Tl --change-stack-guard-on-fork=enable --shared-files=v8_context_snapshot_data:100 --field-trial-handle=3,i,1097686444200197014,6574062328990545257,262144 --enable-features=NetworkService,NetworkServiceInProcess --disable-features=BackForwardCache,PaintHolding,Translate --variations-seed-version --trace-process-track-uuid=3190708989122997041 (dns block)
  • Triggering command: /opt/google/chrome/chrome /usr/bin/google-chrome-stable --disable-REDACTED-networking --enable-features=NetworkService,NetworkServiceInProcess --disable-REDACTED-timer-throttling --disable-REDACTEDing-occluded-windows --disable-breakpad --disable-client-side-phishing-detection --disable-component-extensions-with-REDACTED-pages --disable-default-apps --disable-dev-shm-usage --disable-extensions --disable-features=Translate,BackForwardCache --disable-hang-monitor --disable-ipc-flooding-protection --disable-popup-blocking --disable-prompt-on-repost --disable-renderer-REDACTEDing --disable-sync --force-color-profile=srgb --metrics-recording-only (dns block)
• https://storage.googleapis.com/chrome-for-testing-public/143.0.7499.4/linux64/chrome-headless-shell-linux64.zip
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/catalyst/catalyst/node_modules/playwright-core/lib/server/registry/oopDownloadBrowserMain.js (http block)
• https://storage.googleapis.com/chrome-for-testing-public/143.0.7499.4/linux64/chrome-linux64.zip
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/catalyst/catalyst/node_modules/playwright-core/lib/server/registry/oopDownloadBrowserMain.js (http block)
• safebrowsingohttpgateway.googleapis.com
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=none --disable-dev-shm-usage --use-angle=swiftshader-webgl --mute-audio --crashpad-handler-pid=3500 --enable-crash-reporter=, --noerrdialogs --user-data-dir=/tmp/puppeteer_dev_chrome_profile-xzu4Tl --change-stack-guard-on-fork=enable --shared-files=v8_context_snapshot_data:100 --field-trial-handle=3,i,1097686444200197014,6574062328990545257,262144 --enable-features=NetworkService,NetworkServiceInProcess --disable-features=BackForwardCache,PaintHolding,Translate --variations-seed-version --trace-process-track-uuid=3190708989122997041 (dns block)
  • Triggering command: /opt/google/chrome/chrome /usr/bin/google-chrome-stable --disable-REDACTED-networking --enable-features=NetworkService,NetworkServiceInProcess --disable-REDACTED-timer-throttling --disable-REDACTEDing-occluded-windows --disable-breakpad --disable-client-side-phishing-detection --disable-component-extensions-with-REDACTED-pages --disable-default-apps --disable-dev-shm-usage --disable-extensions --disable-features=Translate,BackForwardCache --disable-hang-monitor --disable-ipc-flooding-protection --disable-popup-blocking --disable-prompt-on-repost --disable-renderer-REDACTEDing --disable-sync --force-color-profile=srgb --metrics-recording-only (dns block)
• www.google.com
  • Triggering command: /proc/self/exe /proc/self/exe --type=utility --utility-sub-type=network.mojom.NetworkService --lang=en-US --service-sandbox-type=none --disable-dev-shm-usage --use-angle=swiftshader-webgl --mute-audio --crashpad-handler-pid=3500 --enable-crash-reporter=, --noerrdialogs --user-data-dir=/tmp/puppeteer_dev_chrome_profile-xzu4Tl --change-stack-guard-on-fork=enable --shared-files=v8_context_snapshot_data:100 --field-trial-handle=3,i,1097686444200197014,6574062328990545257,262144 --enable-features=NetworkService,NetworkServiceInProcess --disable-features=BackForwardCache,PaintHolding,Translate --variations-seed-version --trace-process-track-uuid=3190708989122997041 (dns block)
  • Triggering command: /opt/google/chrome/chrome /usr/bin/google-chrome-stable --disable-REDACTED-networking --enable-features=NetworkService,NetworkServiceInProcess --disable-REDACTED-timer-throttling --disable-REDACTEDing-occluded-windows --disable-breakpad --disable-client-side-phishing-detection --disable-component-extensions-with-REDACTED-pages --disable-default-apps --disable-dev-shm-usage --disable-extensions --disable-features=Translate,BackForwardCache --disable-hang-monitor --disable-ipc-flooding-protection --disable-popup-blocking --disable-prompt-on-repost --disable-renderer-REDACTEDing --disable-sync --force-color-profile=srgb --metrics-recording-only (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[dgreif]

I got the tests passing in a different branch so no need to convert for now.