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Quality Engineering
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min read
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January 10, 2025

Testing strategies for a decoupled Drupal site

Testing strategies for a decoupled Drupal site
Table of contents

Decoupled Drupal changes how websites and apps work by separating the back-end, where content is managed, from the front-end, where users interact. 

This setup allows the same content to be delivered to multiple platforms in different ways. For example, a university might use Drupal to manage its course catalog, displaying it on their website, a student mobile app, and even digital kiosks across campus. 

Each platform looks and feels different but pulls data from the same source.

Another case could be an e-commerce site where the back-end manages product listings, inventory, and pricing, while the front-end is tailored for web browsers, mobile apps, and in-store screens. 

This separation allows for flexibility in design and functionality for each platform while keeping the core content consistent.

With this flexibility comes the need for more focused testing. For instance, QA teams need to ensure the back-end sends accurate product details to all front-end systems and that those systems display the information correctly, whether it’s a mobile app showing product availability or a website applying promotional pricing.

 Decoupled Drupal creates new opportunities for better user experiences but also requires careful testing to make sure all parts work smoothly together.

The decoupled Drupal model

Before jumping into the testing approach, we need to understand what decoupled (headless) Drupal means. 

In a traditional Drupal setup, the backend, which handles content management, and the frontend, which displays the content, are closely integrated and use the same URL. 

In a decoupled setup, the Drupal backend handles content management (adding and managing content), while the frontend is built with JavaScript frameworks like React, and Next and content displays via APIs.

The decoupled Drupal model
The decoupled Drupal model

1. Client Request    --->   User requests page 

2. Server Response (HTML Shell + JS)  ---> 

3. Front-End JavaScript Framework Activated --->  Server delivers the front-end HTML shell with the required JS framework (React/Vue/Angular)

4. Front-End Executes JavaScript Framework (JS initialization)

5. Initial HTML Rendered by the JS Framework (initial loading without full content)

 6. Front-End Executes API Calls to Drupal for Dynamic Content (via REST, GraphQL, or JSON: API)

  7. Drupal API Receives and Responds with Content in JSON Format

  8. Front-End Updates UI with Retrieved Content

Execution steps

  1. User requests page from server:
    • The user navigates to a URL in their browser.
    • A request is sent to the server, typically through a CDN or a front-end hosting service.
  2. Server responds with an initial HTML shell and JavaScript:
    • The server responds by sending a basic HTML shell, including links to JavaScript files that initialize the front-end framework (React, Vue, or Angular).
  3. JavaScript framework executes (client-side rendering):
    • Once the HTML is loaded, the JavaScript framework is executed on the client side.
    • The front-end framework initializes, setting up the client-side logic for rendering the page.
  4. Initial HTML rendering (no data yet):
    • The JavaScript framework renders a skeleton page version, typically without actual content (loading states might be displayed).
    • This initial render allows the front-end to handle routing and define the page structure.
  5. API requests for content:
    • The front-end framework then issues API requests to the Drupal back-end using endpoints provided by REST, JSON, or GraphQL to fetch dynamic content.
    • The request specifies what content is needed based on the page being viewed.
  6. API response from Drupal:
    • Drupal receives the API request, processes it, and sends back the requested content in JSON format.
    • This data might include structured content like articles, images, and metadata.
  7. Front-End receives content and renders final page:
    • The front-end framework receives the JSON response and dynamically updates the HTML structure to display the content.
    • The page is now fully rendered with all content in place.

Critical QA considerations for testing a decoupled Drupal site

1. API testing: the backbone of communication

In decoupled Drupal, the back-end provides data via APIs (usually RESTful or GraphQL), while the front-end consumes these APIs to render content. Testing APIs is critical to ensure:

  • Correct data retrieval: APIs must return the proper data structures and formats (e.g., JSON).
  • Error handling: Ensure APIs handle exceptions, such as invalid queries or network errors.
  • Authentication & authorization: Verify proper access control to sensitive endpoints.
  • Performance: Test the API's speed and scalability, especially under heavy loads.

Tools like Postman or SOAP UI can automate API testing, ensuring reliability across multiple scenarios.

API testing

2. Front-End testing: user experience at the forefront

The decoupled front-end introduces additional layers of complexity that QA teams must account for:

  • UI/UX testing: The front-end, often built using frameworks like React or Vue, needs to be tested for usability, responsiveness, and accessibility across devices and browsers.
  • Cross-browser compatibility: Ensure that the decoupled front-end works seamlessly across different browsers (Chrome, Firefox, Safari, etc.).
  • End-to-end (E2E) testing: Tools like Cypress or Selenium simulate real user interactions, ensuring that front-end workflows are functional and intuitive.

3. Content consistency & synchronization

In a decoupled setup, content is often authored in Drupal but consumed by various front-end applications. Ensuring content synchronization is crucial:

  • Content validation: Verify that the data entered in Drupal is displayed correctly on the front-end, without truncation or formatting errors.
  • Caching issues: Ensure the front-end handles caching properly, delivering updated content to users without unnecessary delays.
  • Real-time updates: If the front-end consumes real-time data (e.g., via WebSockets), test how it handles updates, especially during simultaneous data changes.

4. Performance testing: keeping both sides optimized

A decoupled architecture can introduce performance challenges due to the need for constant API requests and responses. QA teams should focus on:

  • API performance: Ensure that API calls are optimized, minimizing latency and server load.
  • Front-end load testing: Ensure that the front-end remains responsive even when rendering large datasets or handling concurrent users.
  • Network latency: Test how the front-end performs in different network conditions (e.g., slow connections) and optimize for speed and user experience.

5. Security testing: protecting the layers

Decoupled sites are exposed to more security vulnerabilities since both the API and the front-end are open entry points. Security testing should include:

  • API security: Ensure that all endpoints are secure, using proper authentication methods (OAuth, JWT, etc.).
  • Cross-origin resource sharing (CORS): Validate CORS policies to prevent unauthorized access to APIs from foreign domains.
  • Front-end vulnerabilities: Test for common vulnerabilities like XSS, CSRF, and other security flaws in the front-end.

6. Regression testing: continuous integration

Decoupled architectures tend to involve frequent updates to both the back-end and front-end, which can break existing functionality if not tested thoroughly. Implementing automated regression testing is crucial:

  • Automated testing suites: Create test suites using tools like Jenkins, CircleCI, or GitLab CI to run tests after every code change.
  • Smoke testing: After each deployment, ensure that the critical features of both the API and front-end are functioning correctly.

7. Visual regression testing

Changes in the front-end can introduce unintended design issues. Visual regression testing can be employed to ensure that the UI remains consistent after code changes:

  • Tools: Use tools like Percy or BackstopJS to capture screenshots of pages before and after changes, comparing them for inconsistencies.
  • CSS and layout testing: Test front-end layout across multiple screen sizes to ensure design integrity.

Best practices for QA in decoupled Drupal

Quality Assurance (QA) for a decoupled Drupal site involves unique challenges and considerations due to the separation of the frontend and backend. 

Here are some best practices to ensure a thorough and effective QA process:

  1. Decoupled architecture understanding
    • Knowledge of Frontend and Backend: QA teams should understand the Drupal backend and the chosen frontend technology (like React, and Angular). 
      This understanding is essential to identify integration issues and areas that require focused testing.‍
    • Knowledge of APIs: Since decoupled Drupal sites depend on APIs for communication between the frontend and backend, it is necessary to understand how these APIs work, their endpoints, and the expected data formats.
  1. QA documentation
    • Test plan: Create a detailed test plan that outlines the scope, objectives, and specific areas of focus for testing, including both functional and non-functional requirements.‍
    • Detailed test cases: When working with a decoupled Drupal site, it is essential to design detailed test cases that address both the frontend and backend components to ensure coverage and smooth integration between these layers.‍
    • User help documentation: User help documentation is designed to assist users in understanding how to use a product, service, or software application effectively. It provides step-by-step instructions, guidelines, troubleshooting tips, and other helpful information to ensure a smooth user experience.
  1. Integration testing
    Validate the integration between the frontend and backend. Ensure that data flows correctly through APIs and test the data flow between Drupal’s backend and the decoupled frontend to ensure that data is accurately processed, transformed, and displayed.
  1. Continuous Integration/Continuous Deployment (CI/CD):
    Implement CI/CD pipelines to automate testing and deployment processes. This ensures that tests are run regularly and that new changes do not introduce regressions.
    ‍
  2. Team collaboration
    Maintain strong communication between frontend, backend, and QA teams to ensure alignment on requirements, testing strategies, and timelines.

Conclusion

Picture a system where content flows effortlessly from a single source to multiple platforms, each tailored for a unique audience. 

Decoupled Drupal makes this possible by separating the back-end, where content is stored and managed, from the front-end, where users interact. 

This separation allows organizations to deliver consistent, reliable information across websites, apps, and other digital experiences, all while customizing how it looks and functions for each platform.

But this flexibility brings complexity. With the back-end and front-end working independently, ensuring smooth communication between them becomes critical. 

Every part of the system needs to perform flawlessly, from how content is fetched and displayed to how it responds to user interactions. 

Testing is the glue that holds this system together, verifying that each piece works on its own and as part of a greater whole.

Through careful planning and a range of testing methods, decoupled Drupal evolves into more than a system—it becomes a platform capable of meeting diverse needs with precision. 

It’s about more than delivering content; it’s about delivering experiences that work everywhere, every time.

Written by
Kanchan Bhogade
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