All About the Cache: 6 Cache Testing Lessons from an eCommerce Project

Have you ever updated content in a CMS (Content Management System) only to find that the changes are not reflecting on the live site—even after developers confirm a successful deployment? I encountered this during a critical e-commerce project: users occasionally saw outdated pricing or promotions, risking trust and revenue. As a QA professional, I initially focused a lot on UI testing, but this experience reshaped my perspective.

I learned that cache testing is a vital approach for consistent user experiences. Caching issues often hide undetected by the traditional UI checks, causing discrepancies like stale content for specific users or regions. Without validating cache expiration, headers, or CDN layers, even flawless deployments can fail to deliver the correct information globally.

Now, I treat cache testing and validation as non-negotiable—ensuring users see the right data, on every device, in real time. 

What is Cache Testing?

The Real-World Challenge 

Cache testing helps us catch issues that UI testing alone can't find. For example, when admins publish there product changes, a user in the United States/Canada sees different product prices and than a user in the Caribbean, or when your marketing team's latest content updates aren't showing up for all customers at the same time - these are cache-related issues that impact our users directly.

When it comes to testing e-commerce platforms, this means dealing with constantly changing of content like:

• Product prices, descriptions and images

• Promotional content

• Customer reviews

• Search and filter functionality

• Cart and checkout processes

• Third-party integrations

Understanding Proxy Caching: A QA Perspective 

One way teams scale their applications is by using proxy caching. Think of proxy caching like this: instead of your website sending fresh content to every user, it creates quick-access copies stored closer to them.

Let me share what proxy Cache testing looked like for me. As the QA lead during that recent e-commerce project, it involved verifying these cache systems work correctly before launch.

This meant I had to:

• Check if the right content is being saved in the JSON configuration file for a content management system (CMS) proxy cache settings

• Make sure users got the correct version of saved content in preview and production views

• Test how the system handled content updates between CMS 

• Verify performance stayed smooth while loading

Why does this matter? Because getting it wrong means users might see outdated prices, broken images, or slow-loading pages. On my project, catching these issues during testing saved us from some major headaches after launch.

If you want the technical details about proxy caching? Check out this guide from IOriver.

Practical Testing Tips and Key Insights From My Experience

1. Build Strong Team Collaboration

   Working closely with frontend and backend teams allowed us to uncover critical issues early. On my recent project, this collaboration helped us catch cache problems before they hit production. What worked for me:
   

   • Proactively scheduling regular check-ins with both teams to understand cache implementation

   • Quick sharing of findings across teams ( I used mindmapping to do this)

   • Facilitate joint problem-solving sessions when issues appear

   • Engage clear communication about cache configuration changes
     

2. Set Up Your Testing Foundation Across All Cache Layers After establishing team collaboration, I focused on these three critical areas: 

   • Browser (Front-End) Cache Testing:

     1. Verify that the browser cache headers are correctly set

     2. Test cache invalidation when users make updates for critical user journey’s

     3. Check how different browsers handle cached content (cross browser testing)
        

   • CMS Cache Testing:

     1. Compare preview versus published content behavior

     2. Verify content updates show correctly across all environments

     3. Monitor SEO elements for proper updates across all environments
        

   • API and Database (Back-End) Cache Testing:

     1. Check cached responses stay fresh

     2. Test cache clearing works properly (manually and automatically)

     3. Verify performance meets benchmarked goals

     

     Mind map of the QA Cache Testing Process showing the different layers and components to test

     
     

3. Check for Cache Invalidation Gaps  These are the sneaky issues that can cause major headaches. I found these common problems:

   • New components not showing selected updates in preview or production

   • Missing cache handlers in frontend code

   • Content changes appearing for some users but not others

   • Different content versions showing across locations
     

4. Test Cache Impact with Every Feature 

   Each new feature can affect caching differently. Here's my testing approach:

   • Run cache behavior tests for new features

   • Check existing cache systems still work (regression testing)

   • Verify component layouts work in all cache states

   • Document any changes in cache patterns
     

5. Verify Data Consistency  This is especially important for e-commerce sites. Focus on:

   • Inventory numbers matching across platforms

   • Order data staying accurate during cache updates

   • Cache refresh timing being consistent

   • Error handling working correctly

📝 Tips from My Experience:

• Start with browser cache testing as it's closest to user experience

• Document cache clearing steps for your team

• Keep a log of cache-related issues you find

• Test cache behavior during deployments

It’s argued that testing cache logic should be done mainly by Developers. I slightly agree with this statement but based on my experience, having QA can provide guidance and support during the creation of the tests can help to catch issues early. 

I remember how helpful it was to visualize all the cache testing components during our project. I've created a mind map that shows exactly how I structured our testing approach across all cache layers. You can use it as a template for your own projects.

Download the Full Cache Testing Mind Map

Note: I'm still learning about cache performance monitoring and would love to hear your experiences with it. What monitoring tools have worked best for your team?

Happy Testing!