playwright-mcp

name	playwright-mcp
description	Browser testing, web scraping, and UI validation using Playwright MCP. Use this skill when you need to test Streamlit apps, validate web interfaces, test responsive design, check accessibility, or automate browser interactions through MCP tools.

Playwright MCP Testing

Automate browser testing, web scraping, and UI validation using Playwright MCP server for comprehensive browser automation.

Quick Start

Core Testing Workflow:

1. Navigate to application
2. Take snapshot (accessibility tree)
3. Interact with elements
4. Verify expected behavior
5. Take screenshots for documentation

Key Tools

Navigation & Waiting

• browser_navigate - Load URL
• browser_wait_for - Wait for time, text, or element

Interaction

• browser_click - Click buttons and elements
• browser_fill_form - Batch fill multiple form fields
• browser_type - Type into inputs
• browser_select_option - Select dropdown options

Validation

• browser_snapshot - Accessibility tree (for AI analysis)
• browser_take_screenshot - Visual capture
• browser_console_messages - Check for JavaScript errors

Testing Patterns

Page Load Verification

Navigate to http://localhost:8501
Wait 5 seconds
Take snapshot
Verify expected elements present

Form Testing

Fill form fields (use browser_fill_form for speed)
Click Submit button
Wait for "Success" text to appear
Take screenshot

Responsive Design

Resize to 375x667 (mobile)
Take screenshot
Resize to 1920x1080 (desktop)
Take screenshot

Multi-Page Navigation

Navigate to homepage
Click navigation link
Verify URL changed
Verify new page content

Best Practices

✅ DO:

• Use browser_snapshot for AI analysis
• Wait for content (3-5 seconds)
• Batch form fields with browser_fill_form
• Use element refs from snapshots for reliable clicks
• Check console for errors

❌ AVOID:

• Using screenshots when you need to interact
• Typing each field individually
• Skipping waits for dynamic content
• Ignoring console errors

Common Workflows

Pre-Deployment Testing

• Test all pages load without errors
• Verify navigation works
• Test forms submit successfully
• Check data displays correctly
• Validate responsive design (375, 768, 1920px)
• Check console for JavaScript errors

Accessibility Validation

• Take snapshot of each page
• Verify interactive elements have labels
• Check heading hierarchy
• Verify form labels associated

Visual Regression

• Take full-page screenshots
• Compare with baseline
• Document changes

Quick Reference

Common Test Flow

Navigate to http://localhost:8501
Wait 5 seconds
Take snapshot
Click element with ref from snapshot
Wait for "Success" text
Take screenshot

Responsive Testing

Resize to 375x667  # Mobile
Take screenshot
Resize to 768x1024  # Tablet
Take screenshot
Resize to 1920x1080  # Desktop
Take screenshot

Form Submission

Fill form fields (batch)
Click Submit
Wait for success message
Verify in snapshot

Error Checking

Get console messages (onlyErrors=true)
Get network requests
Verify no 404s or 500s

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Troubleshooting

Issue	Solution
Browsers not installed	Run npx @playwright/mcp browser install
Element not found	Take snapshot first to get current page state and exact ref
Tests too slow	Use browser_fill_form instead of multiple browser_type
MCP not starting	Restart IDE, verify mcp.json is valid JSON
Timeout errors	Increase wait times or use browser_wait_for with specific conditions
Screenshots blank	Ensure page is fully loaded before taking screenshot
Console errors not showing	Use browser_console_messages with onlyErrors=true parameter

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Resources

• TESTING_PATTERNS.md - Common test scenarios (coming soon)
• STREAMLIT_TESTING.md - Streamlit-specific patterns (coming soon)
• ACCESSIBILITY.md - Accessibility testing workflows (coming soon)
• mcp-config.json - MCP server configuration