| name | eds-block-testing |
| description | Guide for testing EDS blocks using test.html files and the development server. Covers test file structure, EDS core integration, testing patterns, and debugging workflows for Adobe Edge Delivery Services blocks. Use when this capability is needed. |
| metadata | {"author":"ddttom"} |
EDS Block Testing Guide
Purpose
Guide developers through testing Adobe Edge Delivery Services (EDS) blocks using test.html files, the development server, and proper EDS integration patterns.
When to Use This Skill
Automatically activates when:
- Creating or editing
test.html files in block directories
- Working with keywords: "test block", "test.html", "debug block"
- Implementing block testing patterns
- Using the development server
Quick Start: Create a Test File
Every block should have a test.html file in its directory:
blocks/your-block/
├── your-block.js
├── your-block.css
├── README.md
├── EXAMPLE.md
└── test.html ← Create this file
Standard Test File Template
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Your Block Test - EDS Native Pattern</title>
<link rel="stylesheet" href="/styles/styles.css">
<link rel="stylesheet" href="/styles/fonts.css">
<link rel="stylesheet" href="/styles/lazy-styles.css">
<style>
body {
padding: 2rem;
background: var(--light-color);
}
.test-content {
max-width: 1200px;
margin: 0 auto;
background: var(--background-color);
padding: 2rem;
border-radius: 8px;
}
.test-section {
margin: 2rem 0;
padding: 1rem;
border: 1px solid var(--dark-color);
border-radius: 4px;
}
body.appear {
display: block;
}
</style>
</head>
<body>
<div class="test-content">
<h1>Your Block Test Page</h1>
<div class="test-section">
<h2>Test Case 1: Basic Usage</h2>
<div class="your-block">
<div>
<div>Title 1</div>
<div>Description 1</div>
</div>
<div>
<div>Title 2</div>
<div>Description 2</div>
</div>
</div>
</div>
<div class="test-section">
<h2>Test Case 2: With Images</h2>
<div class="your-block">
<div>
<div>
<picture>
<img src="/images/test-image.jpg" alt="Test">
</picture>
</div>
<div>Content with image</div>
</div>
</div>
</div>
</div>
<script type="module">
import {
sampleRUM,
loadBlock,
loadCSS
} from '/scripts/aem.js';
sampleRUM('top');
window.addEventListener('load', () => sampleRUM('load'));
document.body.classList.add('appear');
const blocks = document.querySelectorAll('.your-block');
for (const block of blocks) {
try {
block.classList.add('block');
await loadBlock(block);
console.log(`✅ Block loaded: ${block.className}`);
} catch (error) {
console.error(, error);
}
}
</script>
</body>
</html>
Important Notes:
- The
document.body.classList.add('appear') line is required and must be called before loadBlock(). EDS hides the body by default (body { display: none; } in styles/styles.css) to prevent Flash of Unstyled Content (FOUC). Adding the appear class makes the page visible. In production, EDS adds this automatically, but test files must add it manually.
- The
.block class is automatically added by the script (line block.classList.add('block')) to mimic EDS production behavior. In your HTML, only use the block name class (e.g., class="your-block").
- This approach ensures test files behave identically to production where EDS's
decorateBlock() adds the .block class automatically.
Development Server Workflow
Start the Server
npm run debug
The server starts on http://localhost:3000 with:
- Automatic proxy fallback to production site
- CORS headers for cross-origin requests
- Enhanced logging for debugging
- Hot-reload support
Access Your Test
http://localhost:3000/blocks/your-block/test.html
Development Flow
- Edit your block JavaScript or CSS
- Refresh the test page in your browser
- Check the browser console for errors
- Iterate and test
EDS Block Structure in Test Files
Basic Two-Column Structure
<div class="your-block">
<div>
<div>Column 1 Content</div>
<div>Column 2 Content</div>
</div>
<div>
<div>Column 1 Content</div>
<div>Column 2 Content</div>
</div>
</div>
Important:
- This structure matches how EDS creates blocks from Google Docs tables
- The
.block class is automatically added by EDS's decorateBlock() function in production
- For test files, you can either:
- Add
.block manually: <div class="your-block block">
- Let your test script add it automatically (recommended - mimics production behavior)
With Images
<div class="your-block">
<div>
<div>
<picture>
<source type="image/webp" srcset="/image.webp">
<img src="/image.jpg" alt="Description" loading="lazy">
</picture>
</div>
<div>Text content</div>
</div>
</div>
With Links
<div class="your-block">
<div>
<div>
<a href="https://example.com">Link Text</a>
</div>
<div>Description</div>
</div>
</div>
With Data Attributes
<div class="your-block"
data-layout="grid"
data-columns="3"
data-autoplay="true">
</div>
Note: Examples show blocks without the .block class. Your test script should add it automatically to mimic EDS production behavior.
Loading Blocks Programmatically
Basic Block Loading
<script type="module">
import { loadBlock } from '/scripts/aem.js';
const block = document.querySelector('.your-block');
await loadBlock(block);
</script>
Loading Multiple Blocks
<script type="module">
import { loadBlock } from '/scripts/aem.js';
const blocks = document.querySelectorAll('.block');
for (const block of blocks) {
await loadBlock(block);
}
await Promise.all(
Array.from(blocks).map(block => loadBlock(block))
);
</script>
With Error Handling
<script type="module">
import { loadBlock } from '/scripts/aem.js';
const blocks = document.querySelectorAll('.block');
for (const block of blocks) {
try {
await loadBlock(block);
console.log(`✅ Loaded: ${block.className}`);
} catch (error) {
console.error(`❌ Failed to load: ${block.className}`, error);
block.innerHTML = '<p class="error">Failed to load block</p>';
}
}
</script>
Testing Different Scenarios
Test Empty Content
<div class="test-section">
<h2>Test Case: Empty Content</h2>
<div class="your-block block">
</div>
</div>
Test Invalid Content
<div class="test-section">
<h2>Test Case: Invalid Structure</h2>
<div class="your-block block">
<div>
<div>Only One Column</div>
</div>
</div>
</div>
Test Edge Cases
<div class="test-section">
<h2>Test Case: Very Long Content</h2>
<div class="your-block block">
<div>
<div>Short title</div>
<div>Lorem ipsum dolor sit amet, consectetur adipiscing elit... (very long text)</div>
</div>
</div>
</div>
Test Responsive Behavior
<style>
.test-mobile {
max-width: 375px;
margin: 0 auto;
}
.test-tablet {
max-width: 768px;
margin: 0 auto;
}
</style>
<div class="test-section test-mobile">
<h2>Test Case: Mobile View (375px)</h2>
<div class="your-block block">
</div>
</div>
<div class="test-section test-tablet">
<h2>Test Case: Tablet View (768px)</h2>
<div class="your-block block">
</div>
</div>
Debugging Tips
Console Logging
<script type="module">
import { loadBlock } from '/scripts/aem.js';
const block = document.querySelector('.your-block');
console.group('Block Loading');
console.log('Block element:', block);
console.log('Block classes:', block.className);
console.log('Block content before:', block.innerHTML);
await loadBlock(block);
console.log('Block content after:', block.innerHTML);
console.groupEnd();
</script>
Timing Performance
<script type="module">
import { loadBlock } from '/scripts/aem.js';
const block = document.querySelector('.your-block');
console.time('Block Load Time');
await loadBlock(block);
console.timeEnd('Block Load Time');
</script>
Check Network Requests
Open Chrome DevTools → Network tab to see:
- Which CSS files are loaded
- Which JavaScript modules are loaded
- Any failed requests (404, 500, etc.)
Common Issues and Solutions
Issue: Page is Blank or Invisible
Symptoms:
- Page loads but nothing displays
- Browser shows white/blank screen
- Console shows no JavaScript errors
- Elements exist in DOM but aren't visible
Root Cause: CSS class name conflicts with EDS reserved names
Solution: Never use these class patterns in your CSS or JavaScript:
.{blockname}-container - EDS adds to parent <section> elements.{blockname}-wrapper - EDS adds to block parent <div> wrappers.block - EDS adds to all block elements (avoid styling globally).section - EDS adds to all sections (avoid styling globally).button-container - EDS adds to button parent elements.default-content-wrapper - EDS adds to default content wrappers
Example of the bug:
.overlay-container {
position: fixed;
z-index: 999;
opacity: 0;
}
.overlay-backdrop {
position: fixed;
z-index: 999;
opacity: 0;
}
Why this happens:
- EDS's
decorateBlock() adds .{blockname}-container to parent sections (aem.js:684)
- Your CSS targets
.{blockname}-container for your component
- Browser applies your styles to the section instead of your element
- Section gets
position: fixed; opacity: 0 making page invisible
Other global classes that can cause issues:
.block { position: fixed; }
.section { display: none; }
.button-container { overflow: hidden; }
How to debug:
- Open browser console
- Run:
document.querySelector('section').className
- If you see
{blockname}-container in the class list, rename your CSS classes
- Check if styling global classes like
.block or .section with layout properties
Issue: Block CSS Not Loading
Solution: Ensure your CSS file has the exact same name as your JS file:
blocks/your-block/
├── your-block.js ✅ Matches
├── your-block.css ✅ Matches
└── test.html
Issue: Block Not Rendering
Check:
- Console for JavaScript errors
- Block structure matches expected pattern
decorate function is exported as default- Block class name is correct
Issue: Images Not Loading
Solution: Use absolute paths from project root:
<img src="image.jpg">
<img src="/images/image.jpg">
Interactive Testing Tools
Add Test Controls
<div class="test-controls">
<button onclick="reloadBlock()">Reload Block</button>
<button onclick="clearBlock()">Clear Block</button>
<button onclick="logBlockState()">Log State</button>
</div>
<script type="module">
import { loadBlock } from '/scripts/aem.js';
const block = document.querySelector('.your-block');
window.reloadBlock = async () => {
console.log('Reloading block...');
block.innerHTML = originalHTML;
await loadBlock(block);
};
window.clearBlock = () => {
block.innerHTML = '';
};
window.logBlockState = () => {
.(, {
: block.,
: block..,
: block.
});
};
originalHTML = block.;
(block);
Data Attribute Testing
<div class="test-controls">
<label>
Layout:
<select onchange="updateLayout(this.value)">
<option value="grid">Grid</option>
<option value="list">List</option>
<option value="carousel">Carousel</option>
</select>
</label>
</div>
<div class="your-block block" data-layout="grid">
</div>
<script type="module">
import { loadBlock } from '/scripts/aem.js';
const block = document.querySelector('.your-block');
const originalHTML = block.innerHTML;
window.updateLayout = (layout) => {
block. = originalHTML;
block.. = layout;
(block);
};
(block);
Accessibility Testing
Test Keyboard Navigation
<div class="test-section">
<h2>Accessibility Test</h2>
<p>Use Tab to navigate, Enter/Space to activate</p>
<div class="your-block block">
</div>
</div>
<script type="module">
document.addEventListener('keydown', (e) => {
console.log('Key pressed:', e.key, 'on:', e.target);
});
</script>
Test Screen Reader Compatibility
Use Chrome DevTools:
- Open DevTools → Elements
- Right-click element → Inspect Accessibility Properties
- Check ARIA labels, roles, and descriptions
Performance Testing
Measure Rendering Time
<script type="module">
import { loadBlock } from '/scripts/aem.js';
const block = document.querySelector('.your-block');
performance.mark('block-load-start');
await loadBlock(block);
performance.mark('block-load-end');
performance.measure(
'block-load-time',
'block-load-start',
'block-load-end'
);
const measure = performance.getEntriesByName('block-load-time')[0];
console.log(`Block loaded in ${measure.duration.toFixed(2)}ms`);
</script>
Check for Memory Leaks
<script type="module">
import { loadBlock } from '/scripts/aem.js';
const block = document.querySelector('.your-block');
for (let i = 0; i < 100; i++) {
const originalHTML = block.innerHTML;
await loadBlock(block);
block.innerHTML = originalHTML;
}
console.log('Memory test complete - check DevTools Memory tab');
</script>
Related Documentation
Testing Checklist
Before considering your block complete, test:
Next Steps
- Create test.html for your block
- Start the development server:
npm run debug
- Access your test file in the browser
- Test all scenarios and edge cases
- Fix any issues found during testing
- Document test results in your README.md
Remember: Proper testing ensures your block works correctly in all scenarios and provides a great user experience on the production site!
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