Chromium Local Smoke Tests

Context

Use this when the team wants a small, always-on Chromium browser slice that proves real page interaction honestly without creating browser-specific MCP tools.

Pattern

• Prefer Edge + local static HTML for the deterministic slice, then pair it with one stable public-web page for required internet coverage.
• Keep the scope to page content discovery first: landmarks, ARIA-labeled inputs, and buttons.
• Launch Edge as an app window with startup hygiene, --force-renderer-accessibility, and an isolated `--user-data-dir` for reliability.
• Keep the public tier to a stable browser-testing page (for example https://demo.playwright.dev/todomvc/) and assert only long-lived page content such as labeled inputs or links.
• Keep browser chrome, logins, and ambient profile state out of the default slice.

Good first assertions (local tier)

• Landmark or navigation container is discoverable.
• ARIA-labeled search box resolves as Edit.
• ARIA-labeled primary action resolves as Button.

Good second-slice assertions (local interaction tier)

• Add one editable field whose value can be typed and read back to prove ui_type + ui_read.
• Add one always-visible text node to prove baseline ui_read on Chromium page content.
• Add one page-owned post-click assertion (revealed text, changed text, toggled state) to prove ui_click affected the DOM, not just that the automation layer returned success.
• Keep the post-click assertion inside the page content itself; avoid browser chrome, URL assertions, tabs, or address bar checks.

Harness implementation note

• Use app-window launch (--app=) plus accessibility/startup hygiene and an isolated profile, then wait for all page-owned readiness selectors before running assertions. Only if readiness does not appear should the test harness use a narrow, test-only dismissal path for known Edge first-run/sync dialogs; if Stefan's sync popup appears, look specifically for a "Got it" button and dismiss that exact button before proceeding.
• Close the launched Edge window first, then kill the dedicated temp-profile browser process tree only if it fails to exit promptly. Delete the temp profile after teardown.

Good public-site assertions (smoke tier)

• Canonical placeholder or label text as accessible name (e.g., TodoMVC What needs to be done? → Edit).
• Longstanding links or buttons by visible text + stable control type.
• Prefer public demos maintained by browser/tooling vendors over individual-maintained practice sites.
• Use 15s+ timeouts for public pages (vs 5s local) to absorb network latency.

Anti-patterns

• Do not depend on public practice sites whose copy or uptime is outside your control.
• Do not mix address-bar/tab-strip/browser-chrome assertions into the first slice.
• Do not rely on ambient browser state for default coverage; use an isolated browser profile.
• Do not accept clickResult.Success == true as sufficient proof of Chromium interaction; require a page-content effect.