test-cross-browser

name	test-cross-browser
description	Test cross-browser consistency across Chromium, Firefox, and WebKit. Use when user wants to verify browser compatibility, cross-browser layout, or browser-specific issues.
allowed-tools	Bash(playwright-cli:*) Bash(npx:*) Bash(mkdir:*)

Cross-Browser Consistency

Run 10 test cases across 3 parallel agents — one per browser engine (Chromium, Firefox, WebKit). Each agent runs the identical test suite for direct comparison.

Setup

URL="${ARGUMENTS:-http://localhost:3000}"
TIMESTAMP=$(date +%Y%m%d-%H%M%S)
OUTDIR="test-results/test-cross-browser/$TIMESTAMP"
mkdir -p "$OUTDIR/screenshots" "$OUTDIR/snapshots" "$OUTDIR/traces"

Before running, verify prerequisites per references/prerequisites.md.

Parallel Execution — 3 Subagents (one per browser)

Agent 1: Chromium (-s=xb-chromium)

playwright-cli -s=xb-chromium open "$URL" --browser=chrome
playwright-cli -s=xb-chromium tracing-start
playwright-cli -s=xb-chromium screenshot --filename="$OUTDIR/screenshots/chromium-initial.png"
playwright-cli -s=xb-chromium snapshot --filename="$OUTDIR/snapshots/chromium-initial.yaml"

Agent 2: Firefox (-s=xb-firefox)

playwright-cli -s=xb-firefox open "$URL" --browser=firefox
playwright-cli -s=xb-firefox tracing-start
playwright-cli -s=xb-firefox screenshot --filename="$OUTDIR/screenshots/firefox-initial.png"
playwright-cli -s=xb-firefox snapshot --filename="$OUTDIR/snapshots/firefox-initial.yaml"

Agent 3: WebKit (-s=xb-webkit)

playwright-cli -s=xb-webkit open "$URL" --browser=webkit
playwright-cli -s=xb-webkit tracing-start
playwright-cli -s=xb-webkit screenshot --filename="$OUTDIR/screenshots/webkit-initial.png"
playwright-cli -s=xb-webkit snapshot --filename="$OUTDIR/snapshots/webkit-initial.yaml"

Test Cases — Each Agent Runs ALL

TC	Test	How to Check
TC-XB1	Page renders — a11y tree structure matches	snapshot, compare structural elements across browser snapshots
TC-XB2	Forms — fill + submit works	Find form, fill fields with fill, click submit, verify success state
TC-XB3	Navigation — links, back/forward	Click nav links, go-back, go-forward, verify correct pages load
TC-XB4	JS feature support	run-code to test: typeof fetch, typeof Promise, typeof IntersectionObserver, typeof ResizeObserver — all should return 'function'
TC-XB5	CSS consistency — element dimensions within 5px	run-code to measure key element bounding rects, compare across browsers (±5px tolerance)
TC-XB6	CSS Grid/Flexbox renders correctly	run-code to find Grid/Flexbox containers, verify children layout (positions, sizes)
TC-XB7	Custom fonts load correctly	run-code to check document.fonts.ready, then verify computed font-family matches expected
TC-XB8	Animations/transitions render	run-code to check for elements with CSS animation/transition, verify they have non-zero duration
TC-XB9	Scroll behavior — smooth/snap	run-code to check scroll-behavior and scroll-snap-type CSS properties are applied
TC-XB10	Input types — date/color/range	run-code to find specialized input types, verify they render natively (have shadow DOM or platform UI)

After running all tests:

playwright-cli -s=<session> screenshot --filename="$OUTDIR/screenshots/<browser>-final.png"
playwright-cli -s=<session> tracing-stop
playwright-cli -s=<session> close

Fix Loop

After execution, if any tests failed, follow the fix loop process in references/fix-loop.md. Max 3 attempts. Only re-run failed test cases.

Include fix attempt history in the report.

Report Generation

After all 3 agents complete, merge results into $OUTDIR/report.md.

Use a comparison matrix:

Test Case	Chromium	Firefox	WebKit	Consistent?
TC-XB1	✅	✅	✅	✅
TC-XB2	✅	✅	❌	❌
...	...	...	...	...

Highlight inconsistencies with details:

• Which browser failed
• What the difference was (dimensions, behavior, missing feature)
• Suggested fix (polyfill, vendor prefix, fallback)

Cleanup

playwright-cli -s=xb-chromium close 2>/dev/null
playwright-cli -s=xb-firefox close 2>/dev/null
playwright-cli -s=xb-webkit close 2>/dev/null