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.

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>

    <!-- EDS Core Styles -->
    <link rel="stylesheet" href="/styles/styles.css">
    <link rel="stylesheet" href="/styles/fonts.css">
    <link rel="stylesheet" href="/styles/lazy-styles.css">

    <!-- Note: Block CSS is loaded automatically by EDS -->

    <style>
        /* Test-specific styling */
        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;
        }

        /* EDS pattern - ensure body appears */
        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>

            <!-- Your block with test content (note: only block name class, .block is added by script) -->
            <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>

    <!-- EDS Core Scripts -->
    <script type="module">
        import {
            sampleRUM,
            loadBlock,
            loadCSS
        } from '/scripts/aem.js';

        // Initialize RUM (optional for testing)
        sampleRUM('top');
        window.addEventListener('load', () => sampleRUM('load'));

        // CRITICAL: Add body.appear class FIRST (before loadBlock)
        // EDS global styles hide body by default to prevent FOUC
        // This makes the page visible before blocks load
        document.body.classList.add('appear');

        // Load all blocks on the page
        // Mimic EDS behavior: find by block name, add .block class automatically
        const blocks = document.querySelectorAll('.your-block');

        for (const block of blocks) {
            try {
                // Add .block class like EDS decorateBlock() does
                block.classList.add('block');
                await loadBlock(block);
                console.log(`✅ Block loaded: ${block.className}`);
            } catch (error) {
                console.error(`❌ Block failed: ${block.className}`, 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">
    <!-- Row 1 -->
    <div>
        <div>Column 1 Content</div>
        <div>Column 2 Content</div>
    </div>
    <!-- Row 2 -->
    <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">
    <!-- Block content -->
</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');

    // Load blocks sequentially
    for (const block of blocks) {
        await loadBlock(block);
    }

    // Or load in parallel
    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">
        <!-- No content - test error handling -->
    </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>
            <!-- Missing second column -->
        </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">
        <!-- Content -->
    </div>
</div>

<div class="test-section test-tablet">
    <h2>Test Case: Tablet View (768px)</h2>
    <div class="your-block block">
        <!-- Content -->
    </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:

/* ❌ BAD - Will be applied to parent section, not your modal */
.overlay-container {
  position: fixed;
  z-index: 999;
  opacity: 0;  /* Makes entire page invisible! */
}

/* ✅ GOOD - Use different suffix */
.overlay-backdrop {
  position: fixed;
  z-index: 999;
  opacity: 0;  /* Only affects your backdrop element */
}

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:

/* ❌ DANGER - These affect ALL blocks/sections if styled incorrectly */
.block { position: fixed; }           /* Breaks ALL blocks */
.section { display: none; }           /* Hides ALL sections */
.button-container { overflow: hidden; } /* Breaks ALL buttons */

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:

<!-- ❌ BAD -->
<img src="image.jpg">

<!-- ✅ GOOD -->
<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; // Save original
        await loadBlock(block);
    };

    window.clearBlock = () => {
        block.innerHTML = '';
    };

    window.logBlockState = () => {
        console.log('Block state:', {
            className: block.className,
            children: block.children.length,
            innerHTML: block.innerHTML
        });
    };

    // Save original HTML
    const originalHTML = block.innerHTML;
    await loadBlock(block);
</script>

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">
    <!-- Content -->
</div>

<script type="module">
    import { loadBlock } from '/scripts/aem.js';

    const block = document.querySelector('.your-block');
    const originalHTML = block.innerHTML;

    window.updateLayout = async (layout) => {
        block.innerHTML = originalHTML;
        block.dataset.layout = layout;
        await loadBlock(block);
    };

    await loadBlock(block);
</script>

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">
        <!-- Interactive content -->
    </div>
</div>

<script type="module">
    // Log keyboard events for testing
    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');

    // Mark start time
    performance.mark('block-load-start');

    await loadBlock(block);

    // Mark end time
    performance.mark('block-load-end');

    // Measure duration
    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');

    // Load and unload multiple times
    for (let i = 0; i < 100; i++) {
        const originalHTML = block.innerHTML;
        await loadBlock(block);

        // Reset for next iteration
        block.innerHTML = originalHTML;
    }

    console.log('Memory test complete - check DevTools Memory tab');
</script>

Testing Checklist

Before considering your block complete, test:

Basic functionality with standard content
Empty/missing content handling
Very long content (text overflow)
Images load correctly
Links work and have correct targets
Responsive behavior (mobile, tablet, desktop)
Keyboard navigation
Screen reader compatibility
Performance (load time < 100ms for simple blocks)
Browser console shows no errors
Works with multiple instances on same page

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!

Install Skill

SKILL.md