Local Testing with Playwright MCP

Local Testing with Playwright MCP

This skill helps you test the Jekyll site locally and visualize pages using Playwright MCP browser automation.

When to Use This Skill

Use this skill when:

• "Test the local build"
• "Preview the site locally"
• "Visualize local changes"
• "Test with Playwright"
• "Check how the site looks"
• Before committing major changes
• After updating member profiles or content
• When debugging layout or rendering issues

Prerequisites

Ensure Playwright MCP is installed:

claude mcp add playwright npx '@playwright/​mcp@latest'

Workflow

Step 1: Start Jekyll Server

1. Launch the server in background:

   bundle exec jekyll serve --force_polling --livereload
   

   Use run_in_background: true to keep the server running while testing.

2. Wait for server initialization (8-10 seconds):

   sleep 8
   

3. Check server output:

   • Use BashOutput to verify server started successfully
   • Confirm it's running at http://127.0.0.1:4000/
   • Look for "Server running..." message

Step 2: Navigate to Homepage

1. Open homepage with Playwright:

   mcp__playwright__browser_navigate
   url: http://127.0.0.1:4000/
   

2. Verify page loaded:

   • Check page title: "Talmo Lab - Home"
   • Review page snapshot structure
   • Look for key elements (banner, navigation, content)

3. Capture full-page screenshot:

   mcp__playwright__browser_take_screenshot
   filename: homepage-screenshot.png
   type: png
   fullPage: true
   

Step 3: Test Key Pages

Navigate and capture screenshots of important pages:

Team Page

mcp__playwright__browser_navigate
url: http://127.0.0.1:4000/​team/

• Verify all member portraits load
• Check alumni section formatting
• Take full-page screenshot: team-page-screenshot.png

Research Page

mcp__playwright__browser_navigate
url: http://127.0.0.1:4000/​research/

• Verify research areas display correctly
• Check images and formatting
• Take screenshot: research-page-screenshot.png

Publications Page

mcp__playwright__browser_navigate
url: http://127.0.0.1:4000/​publications/

• Verify citations render properly
• Check publication cards/​entries
• Take screenshot: publications-page-screenshot.png

Individual Member Profile

mcp__playwright__browser_navigate
url: http://127.0.0.1:4000/​members/​talmo-pereira.html

• Verify profile image displays
• Check bio formatting
• Verify social links work
• Take screenshot: member-profile-screenshot.png

Step 4: Test Interactive Elements (Optional)

If testing navigation or interactive features:

1. Click navigation links:

   mcp__playwright__browser_click
   element: "Research navigation link"
   ref: [element reference from snapshot]
   

2. Hover over portraits:

   mcp__playwright__browser_hover
   element: "Member portrait"
   ref: [element reference]
   

3. Test responsive behavior:

   mcp__playwright__browser_resize
   width: 375
   height: 667
   

   Then take screenshots at mobile size.

Step 5: Check Console for Errors

Look for any JavaScript errors or 404s:

mcp__playwright__browser_console_messages
onlyErrors: true

Common issues to check:

• Missing images (404 errors)
• Failed CSS/​JS loads
• JavaScript runtime errors

Step 6: Review Screenshots

Present screenshots to user:

• Show what pages were tested
• Highlight any rendering issues
• Note any console errors found
• Summarize overall build health

Step 7: Cleanup

1. Kill the Jekyll server:

   KillShell
   shell_id: [server shell ID]
   

2. Confirm cleanup:

   • Verify server stopped
   • Note that screenshots are saved in .playwright-mcp/ (gitignored)

Common Testing Scenarios

Testing New Member Profile

When adding a new member:

1. Start server
2. Navigate to team page → verify member appears
3. Navigate to member profile → verify all fields render
4. Check profile image displays correctly
5. Verify links (email, GitHub, etc.) are present
6. Take screenshots of both pages

Testing Layout Changes

When modifying CSS or templates:

1. Start server with livereload
2. Navigate to affected pages
3. Take "before" screenshots
4. Make changes (livereload will auto-refresh)
5. Take "after" screenshots
6. Compare visually

Testing Publications

When updating _data/​sources.yaml:

1. Run ./​cite.sh to generate citations
2. Start server
3. Navigate to publications page
4. Verify new publications appear
5. Check formatting of citations
6. Verify links and images

Full Site Regression Test

Before major deployments:

1. Test all main pages (home, team, research, publications, join)
2. Test sample member profiles (PI, PhD, undergrad, alumni)
3. Check footer and navigation on all pages
4. Test at desktop and mobile sizes
5. Review console for any errors
6. Capture screenshots of all tested pages

Screenshot Storage

All screenshots are saved to .playwright-mcp/ directory:

• This directory is automatically gitignored
• Screenshots are for local review only
• Filenames should be descriptive (e.g., team-page-screenshot.png)
• Full-page screenshots recommended for complete context

Troubleshooting

Server Won't Start

Error: "Address already in use"

• Check if Jekyll is already running: lsof -i :4000
• Kill existing process: kill -9 [PID]
• Restart server

Error: "Permission denied"

• Don't run ./​start.sh directly (may not be executable)
• Use: bundle exec jekyll serve --force_polling --livereload

Playwright Can't Connect

Error: "Navigation failed"

• Ensure server is fully started (wait 8-10 seconds)
• Check server logs with BashOutput
• Verify URL is http://127.0.0.1:4000/ (not localhost)

Error: "Browser not installed"

• Run: mcp__playwright__browser_install

Page Rendering Issues

Images not loading

• Check file paths in frontmatter
• Verify images exist in images/ directory
• Look for 404 errors in console

Styling broken

• Check for CSS compilation errors in server logs
• Verify _sass/ files are valid
• Check browser console for CSS load failures

Content missing

• Verify frontmatter is valid YAML
• Check Jekyll build output for warnings
• Look for Liquid template errors in server logs

Best Practices

1. Always test locally before committing:

   • Catches rendering issues early
   • Validates new content appears correctly
   • Ensures no broken links or images

2. Use descriptive screenshot filenames:

   • Include page name and purpose
   • Add date for tracking changes over time
   • Example: team-page-new-members-2025-10-31.png

3. Test multiple page types:

   • Don't just test homepage
   • Verify collection pages (team, publications)
   • Check individual item pages (member profiles)

4. Keep server logs:

   • Check BashOutput periodically
   • Look for build warnings
   • Note any deprecation notices

5. Clean up after testing:

   • Always kill the server when done
   • Review and delete old screenshots
   • Check for any uncommitted test files

Integration with Development Workflow

Standard Development Cycle

1. Make changes to content/​code
2. Run this skill to test locally
3. Review screenshots and console output
4. Fix any issues found
5. Re-test until satisfied
6. Commit changes
7. Push to GitHub (auto-deploys via GitHub Actions)

Pre-Commit Hook Integration

Consider testing before commits:

# In .git/​hooks/​pre-commit
bundle exec jekyll build --quiet

Continuous Testing

For ongoing development:

• Leave server running with livereload
• Make changes and watch auto-refresh
• Use Playwright to capture specific states
• Take screenshots at milestones

See Also

• Jekyll Documentation
• Playwright MCP Documentation
• CLAUDE.md - Project-specific development guidelines
• .github/​workflows/ - CI/​CD configuration