WordPress Theme Testing

Introduction

WordPress theme testing is a critical phase in theme development that ensures your theme functions properly, looks great across different devices, and provides a seamless user experience. In this guide, we'll explore comprehensive approaches to testing WordPress themes before releasing them to the public or submitting them to the WordPress theme directory.

Proper testing helps you:

Identify and fix bugs before users encounter them
Ensure compatibility across different browsers and devices
Verify compliance with WordPress coding standards
Optimize performance and user experience
Build a reputation for quality and reliability

Why Testing Matters

Even the most carefully coded WordPress theme can have unexpected issues when used in different environments or with various plugins. A systematic testing process protects your reputation as a developer and provides a better experience for your users.

Setting Up a Test Environment

Local Development Environment

Before testing your theme widely, set up a local development environment that mimics a typical WordPress installation.

Using Local Tools

Popular options include:

LocalWP: Fast, easy local WordPress development
DevKinsta: Local development tool by Kinsta
XAMPP/MAMP/WAMP: Traditional local server setups

Example Setup with LocalWP

Download and install LocalWP
Create a new site
Install your theme
Add common plugins for testing compatibility

Using WordPress Theme Unit Test Data

The WordPress Theme Unit Test is a standardized XML file containing a variety of content that helps test how your theme handles different content scenarios.

bash
# Download the Theme Unit Test XML file
wget https://raw.githubusercontent.com/WPTT/theme-unit-test/master/themeunittestdata.wordpress.xml

To import the test data:

Go to Tools > Import in your WordPress dashboard
Select "WordPress" and install the importer if prompted
Upload the XML file and import the content

Essential Testing Checklist

1. Functionality Testing

Core WordPress Features

Test how your theme handles:

jsx
// Example of a theme function that might need testing
function mytheme_custom_header_setup() {
    $args = array(
        'default-image'      => get_template_directory_uri() . '/images/header.jpg',
        'width'              => 1000,
        'height'             => 250,
        'flex-width'         => true,
        'flex-height'        => true,
        'uploads'            => true,
        'random-default'     => false,
        'header-text'        => true,
        'default-text-color' => 'fff',
    );
    add_theme_support('custom-header', $args);
}
add_action('after_setup_theme', 'mytheme_custom_header_setup');

Test the following functionality:

Custom headers and backgrounds
Featured images
Widgets and sidebars
Navigation menus
Post formats
Comments
Custom logo

Template Hierarchy

Verify that all template files work correctly:

Single posts (single.php)
Pages (page.php)
Archives (archive.php)
Category pages (category.php)
Search results (search.php)
404 pages (404.php)
Home page (front-page.php, home.php)

2. Visual Testing

Cross-Browser Testing

Test your theme in the following browsers:

Chrome
Firefox
Safari
Edge
Mobile browsers (Chrome for Android, Safari for iOS)

Responsive Design

Check how your theme displays at different viewport sizes:

Desktop (1920×1080, 1366×768)
Tablet (768×1024)
Mobile (375×667, 360×640)

Use developer tools to simulate different screen sizes:

jsx
// Example of media query in your theme's CSS
@media only screen and (max-width: 768px) {
  .site-header {
    padding: 10px;
  }
  
  .main-navigation {
    display: none;
  }
  
  .mobile-menu-toggle {
    display: block;
  }
}

3. WordPress Standards Compliance

Theme Check Plugin

The Theme Check plugin ensures your theme complies with WordPress.org standards.

After installation:

Go to Appearance > Theme Check
Select your theme
Run the test
Review and fix any warnings or errors

Common Issues to Fix

php
// BAD: Direct database queries
$results = $wpdb->get_results("SELECT * FROM $wpdb->posts WHERE post_type = 'post'");

// GOOD: Using WordPress functions
$results = get_posts(array('post_type' => 'post'));

php
// BAD: Hardcoded paths
include('/home/user/public_html/wp-content/themes/my-theme/functions.php');

// GOOD: Using WordPress path functions
include(get_template_directory() . '/functions.php');

4. Performance Testing

Page Speed

Use tools like:

Google PageSpeed Insights
GTmetrix
WebPageTest

Common performance optimizations:

php
// Properly enqueue scripts with dependencies
function mytheme_enqueue_scripts() {
    wp_enqueue_style('mytheme-style', get_stylesheet_uri(), array(), '1.0.0');
    
    // Load jQuery from WordPress core
    wp_enqueue_script('jquery');
    
    // Add custom script with jQuery dependency
    wp_enqueue_script(
        'mytheme-script', 
        get_template_directory_uri() . '/js/script.min.js', 
        array('jquery'), 
        '1.0.0', 
        true // Load in footer
    );
}
add_action('wp_enqueue_scripts', 'mytheme_enqueue_scripts');

Loading Time

Optimize images and assets:

php
// Add theme support for responsive images
add_theme_support('responsive-embeds');
add_theme_support('wp-block-styles');
add_theme_support('align-wide');

5. Accessibility Testing

Use the WAVE (Web Accessibility Evaluation Tool) browser extension to find accessibility issues.

Common accessibility requirements:

html
<!-- BAD: Missing alt text -->
<img src="logo.png">

<!-- GOOD: Proper alt text -->
<img src="logo.png" alt="Company Logo">

html
<!-- BAD: Color contrast issues -->
<p style="color: #aaa; background-color: #fff;">Hard to read text</p>

<!-- GOOD: Sufficient contrast -->
<p style="color: #444; background-color: #fff;">Easy to read text</p>

Automated Testing Tools

Theme Unit Test

We covered Theme Unit Test earlier, but here's an example of what it helps test:

Very long titles
Posts with no title
Sticky posts
Posts with comments disabled
Posts with threaded comments
Password-protected posts
Special formatting and content

WordPress Coding Standards

Use PHP_CodeSniffer with WordPress Coding Standards to automatically check your code:

bash
# Install PHP_CodeSniffer
composer global require squizlabs/php_codesniffer

# Install WordPress Coding Standards
git clone https://github.com/WordPress/WordPress-Coding-Standards.git wpcs
phpcs --config-set installed_paths /path/to/wpcs

# Run the check
phpcs --standard=WordPress your-theme-directory/

Plugin Compatibility Testing

Essential Plugins to Test With

Test your theme with popular plugins like:

WooCommerce
Contact Form 7
Yoast SEO
Elementor/Gutenberg
WP Super Cache or other caching plugins

Testing Process

Install each plugin individually
Test basic functionality
Check for visual conflicts
Test with multiple plugins activated simultaneously

Real-world Examples

Example 1: Testing Theme Customizer Options

php
// Example theme customizer code to test
function mytheme_customize_register($wp_customize) {
    $wp_customize->add_section('mytheme_colors', array(
        'title' => __('Theme Colors', 'mytheme'),
        'priority' => 30,
    ));
    
    $wp_customize->add_setting('header_color', array(
        'default' => '#ffffff',
        'transport' => 'refresh',
        'sanitize_callback' => 'sanitize_hex_color',
    ));
    
    $wp_customize->add_control(new WP_Customize_Color_Control($wp_customize, 'header_color', array(
        'label' => __('Header Color', 'mytheme'),
        'section' => 'mytheme_colors',
        'settings' => 'header_color',
    )));
}
add_action('customize_register', 'mytheme_customize_register');

Test Cases:

Check if color picker displays correctly
Verify color changes apply in real-time with 'transport' => 'refresh'
Test with 'transport' => 'postMessage' for JavaScript-based instant preview
Confirm that default values work correctly

Test how your theme handles different menu scenarios:

No menu assigned
Menu with multiple levels of dropdown
Menu with many items causing wrapping
Menu with custom links, category links, and page links

php
// Example of registering menu locations to test
function mytheme_register_menus() {
    register_nav_menus(array(
        'primary' => __('Primary Menu', 'mytheme'),
        'footer' => __('Footer Menu', 'mytheme'),
        'social' => __('Social Links Menu', 'mytheme'),
    ));
}
add_action('init', 'mytheme_register_menus');

Example 3: Content Layout Testing

Test how your theme handles different content layouts:

html
<!-- Test very wide images -->
<figure class="wp-block-image alignfull">
    <img src="very-wide-image.jpg" alt="Wide landscape">
</figure>

<!-- Test content with no images -->
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam auctor, 
nisl eget ultricies tincidunt, nisl nisl aliquam nisl, eget ultricies nisl 
nisl eget nisl. Nullam auctor, nisl eget ultricies tincidunt, nisl nisl 
aliquam nisl, eget ultricies nisl nisl eget nisl.</p>

<!-- Test content with many short paragraphs -->
<p>Short paragraph 1.</p>
<p>Short paragraph 2.</p>
<p>Short paragraph 3.</p>

Debugging Common Issues

CSS Conflicts

When you find CSS conflicts, use browser developer tools to identify the source:

Inspect the element with issues
Check which CSS rules are being applied and from which files
Use more specific selectors in your theme to override plugin styles

css
/* More specific selectors to override plugin styles */
body.theme-mytheme .plugin-class {
    background-color: transparent !important;
}

JavaScript Errors

Use the browser console to identify JavaScript errors:

javascript
// Safer jQuery usage with noConflict mode
(function($) {
    // Your code here
    $(document).ready(function() {
        $('.menu-toggle').on('click', function(e) {
            e.preventDefault();
            $('.main-navigation').toggleClass('toggled');
        });
    });
})(jQuery);

User Testing

After technical testing, gather feedback from real users:

Create a testing group or beta testers
Provide specific tasks for testers to complete
Ask for screenshots from different devices
Collect feedback systematically using forms or surveys

Theme Documentation and Support

Prepare documentation that helps users test your theme:

Installation instructions
Required and recommended plugins
Setup of demo content
Customization options
FAQs and troubleshooting guides

Summary

Comprehensive WordPress theme testing is essential for delivering a quality product. By systematically testing functionality, appearance, compatibility, performance, and accessibility, you can ensure your theme provides an excellent user experience across different scenarios.

Remember that testing is not a one-time task but should be repeated throughout the development process and after any significant updates. A well-tested theme reduces support requests and builds trust with your users.

Additional Resources

WordPress Theme Review Requirements: The official guidelines for themes submitted to the WordPress.org theme directory
Theme Check Plugin: https://wordpress.org/plugins/theme-check/
WordPress Coding Standards: https://developer.wordpress.org/coding-standards/
WordPress Theme Unit Test Data: https://github.com/WPTT/theme-unit-test

Exercises

Set up a local development environment with the Theme Unit Test data
Run the Theme Check plugin on your theme and fix any issues
Test your theme with a popular page builder plugin and document any conflicts
Create a checklist for your specific theme's features that need testing
Perform accessibility testing and make necessary improvements

By following these testing procedures, you'll create more robust, user-friendly WordPress themes that stand out in the marketplace and provide value to your users.

If you spot any mistakes on this website, please let me know at [email protected]. I’d greatly appreciate your feedback! :)

Introduction​

Why Testing Matters​

Setting Up a Test Environment​

Local Development Environment​

Using Local Tools​

Example Setup with LocalWP​

Using WordPress Theme Unit Test Data​

Essential Testing Checklist​

1. Functionality Testing​

Core WordPress Features​

Template Hierarchy​

2. Visual Testing​

Cross-Browser Testing​

Responsive Design​

3. WordPress Standards Compliance​

Theme Check Plugin​

Common Issues to Fix​

4. Performance Testing​

Page Speed​

Loading Time​

5. Accessibility Testing​

WAVE Tool and Keyboard Navigation​

Automated Testing Tools​

Theme Unit Test​

WordPress Coding Standards​

Plugin Compatibility Testing​

Essential Plugins to Test With​

Testing Process​

Real-world Examples​

Example 1: Testing Theme Customizer Options​

Example 2: Navigation Menu Testing​

Example 3: Content Layout Testing​

Debugging Common Issues​

CSS Conflicts​

JavaScript Errors​

User Testing​

Theme Documentation and Support​

Summary​

Additional Resources​

Exercises​