It’s quite easy to get caught up in the code and test the system from a single perspective – the application creator’s perspective. You already know where the bodies are buried, what each turn leads to, and how to get what you want from the application. But your user doesn’t. To them, it is a new experience; they might not be as patient and crafty with the application as you are. This means that you need to explore the application from the end user’s perspective. This is where end-to-end testing helps.
What is End-to-End Testing?
Instead of testing tiny individual parts of a software application (like just one button or one specific calculation), end-to-end testing means you test the entire flow of a user’s journey through the application, from the very beginning to the very end.
Imagine you’re using an online shopping app. End-to-end testing would check if you can search for a product, add it to your cart, go through the checkout process, and make the payment – basically, testing the entire journey to make sure it’s working properly and the user experience is seamless.
Key Characteristics of End-to-end Testing
- User-centric: Focuses on the user’s perspective.
- Holistic: Covers the entire system, including databases, APIs, external services (like payment gateways, mapping), etc.
- Scenario-based: Follows specific “stories” or use cases (e.g., “User signs up,” “User purchases a product,” “User requests a password reset”).
Why is E2E Testing so Important?
A lot of times, you will see teams focus just on unit and integration testing and call it a day. But while unit and integration tests are crucial for building sturdy components, end-to-end testing is what truly verifies that your entire software machine is ready for the real world.
Catches the “Big Picture” Problems
Individual parts of your software might work perfectly fine on their own, and even when they connect in small groups. But software today is incredibly complex, often interacting with many different components, databases, and even other external services (like payment systems, mapping tools, or social media logins). A tiny hiccup in how one part talks to another, or a subtle timing issue when data moves between different systems, might not show up in smaller tests. These are the kinds of problems that only appear when the entire chain of events unfolds, just like a real user would experience it.
Smooth User Experience
At the end of the day, your software is built for people to use. If their journey through your app is frustrating, confusing, or simply breaks down, they’re likely to leave and not come back. For example, imagine a customer trying to buy something online. They can browse, add to cart, fill out their details… but then the “Place Order” button doesn’t work, or the payment fails mysteriously, or they never receive a confirmation email. From their perspective, the whole experience is broken, even if many parts worked.
Reduces Risky Surprises After Launch
Finding and fixing bugs after your software is released to the public is incredibly costly and damaging. It can lead to bad reviews, lost sales, wasted time from your support team, and a damaged reputation. These are not just minor inconveniences; they can severely impact your business.
Builds Confidence in Your Software
Software is rarely “done”. It constantly evolves with new features, improvements, and bug fixes. Each change carries the risk of accidentally breaking something that used to work. Without comprehensive testing, every time you add a new feature or fix a bug, you’re essentially crossing your fingers and hoping you haven’t introduced a new problem elsewhere in the system.
Types of End-to-End Testing
There are basically two types of E2E testing:
Horizontal Testing Approach
With this technique, your test case is supposed to span across components, that is, horizontally across the width of the application. Let us consider the example of a banking application. The test case could begin from the login page and go to the funds transfer page. Thus, we can see that the test case flows across different components.
Vertical Testing Approach
Contrasting the horizontal approach is the vertical approach which tends to dive deeper into a single component. For example, your test cases would dig deeper into the login module, to begin with. You could test the validations on the username and password sections for valid and invalid combinations of credentials.
How Does E2E Testing Work?
Let us review the steps to carry out E2E testing:
Understanding the Workflow
Before testing begins, it’s important to understand how the entire system or application is supposed to work. This means knowing the different steps a user takes when interacting with the system. For example, in an e-commerce website, a typical user journey would look like this:
- Browsing products: Search for an item you want to buy.
- Adding to cart: Pick a product and add it to your shopping cart.
- Checkout: Provide your address, choose a payment method, and complete the purchase.
- Confirmation: Get an order confirmation and receipt.
These steps form a “workflow” – a series of actions that a user follows to complete a task.
Setting Up the E2E Test
Now that we know what the journey looks like, the testing team sets up the test based on this workflow. The idea is to simulate each step that a real user would take.
For example:
- If you’re testing an online shopping platform, the test script might start by opening the website.
- The next step is to simulate searching for a product.
- After that, the script adds the product to the cart, then goes to checkout and completes the payment.
- Finally, the script confirms the order has been placed successfully.
Executing the E2E Test
Once everything is set up, the test begins! During this phase, a user’s journey through the application is simulated, either manually or through automated tools.
- Manual End-to-End Testing: Here, a human tester goes through the steps as if they were a real user. They might click buttons, enter information, and check if the system behaves correctly at each step.
- Automated End-to-End Testing: For this, software tools (read more about them over here) automatically perform the test steps by mimicking user actions, such as clicking on buttons or filling in forms. Automated tests are often faster and can be run repeatedly without human involvement.
Verifying the Results
After running through the whole journey, the tester checks whether the system worked as expected. Did the shopping cart update correctly when items were added? Was the checkout process smooth? Did the payment go through successfully, and did the confirmation show up?
This step is crucial because it makes sure the system isn’t just working in parts but is functioning as a whole. The test also ensures that there are no broken links or bugs that might affect the user experience.
Identifying Issues
Sometimes, things won’t work as expected. Maybe the website crashes after submitting payment, or the confirmation email doesn’t arrive. In such cases, the test will help identify the problem. By running the test from end to end, it becomes easy to spot where things went wrong – whether it’s in the product search, the cart, or the checkout process.
Fixing the Issues
Once the issues are identified, the development team can step in to fix them. After that, the test is run again to make sure that the fixes work and that nothing else in the system has been broken.
Rerunning the Test
After fixes are made, the test is usually rerun to confirm that everything still works as expected. This step makes sure that the system continues to perform well after any updates or changes.
Example Scenario: Shopping Website
Let’s walk through an example of end-to-end testing in a shopping website.
Imagine a user goes to an online store to buy a jacket. The process might go like this:
- User visits the website – The tester starts by opening the store’s homepage.
- User searches for a jacket – They enter “jacket” in the search bar and click on a result.
- User adds the jacket to the cart – The tester clicks “Add to Cart.”
- User proceeds to checkout – The tester goes to the cart and clicks “Checkout.”
- User enters payment details – They enter a shipping address, select a payment method, and place the order.
- User gets confirmation – The tester verifies the order confirmation page appears.
During end-to-end testing, each step is tested to make sure the system handles it correctly. If everything works as expected – like the product is added to the cart and payment goes through – the test is successful. If there’s an issue at any step (say, the payment fails or the order confirmation page doesn’t appear), the tester can find and report the problem.
When to Perform E2E Testing?
If you know when to perform end-to-end testing, you can focus your efforts and resources on the right moments during development.
After Major Feature Releases
When you release new features or functionality, it’s important to check that everything still works as expected in the larger system.
- Why: New features can impact how existing parts of the system interact with each other. End-to-end testing ensures that all the features work together without breaking the system.
Before a Product Launch or Major Update
Just before launching a product or rolling out a major update, you want to make sure the entire system works properly under real-world conditions.
- Why: A launch is the moment when the software will be used by real users, so you need to verify that all user workflows are smooth and error-free.
After Integrating New Code or Changes
Whenever developers update or add new code to the application, it’s important to check that the changes haven’t caused any issues elsewhere in the system. This is especially crucial for large projects with multiple contributors.
- Why: New code can break existing features, or it might cause unexpected behavior in other parts of the system. End-to-end testing makes sure that the whole system still works together smoothly after the changes.
When Fixing Critical Bugs
If a bug is identified in a specific part of the system, especially one that affects user workflows, you’ll want to perform end-to-end testing after the fix to make sure that the issue is resolved without creating new problems.
- Why: Sometimes, fixing one bug can cause other parts of the system to break, so you need to check the entire workflow to make sure the fix hasn’t introduced other issues.
When Changing or Updating the Infrastructure
If you make changes to the backend infrastructure (like switching to a new server or database), end-to-end testing is essential. Even though the user interface may not change, the underlying infrastructure can affect how the system performs and interacts.
- Why: Changes to the infrastructure could impact the way different parts of the system communicate or handle data. End-to-end testing makes sure that everything continues to work smoothly after these changes.
After a System-Wide Update or Upgrade
Whenever you upgrade a system or its components (like libraries, frameworks, or third-party integrations), end-to-end testing should be performed to make sure that the new version works well with your application.
- Why: System upgrades can sometimes cause compatibility issues or disrupt existing workflows. End-to-end testing makes sure the entire system continues to function properly after the upgrade.
When Testing Critical User Journeys
If your software has key user journeys that are crucial for business (like sign-up, login, or checkout), you should regularly test these flows to ensure they remain functional after updates or changes.
- Why: These critical paths are where users interact with your system most frequently. If these features break, it can directly affect user experience and your business.
During Regression Testing
When you want to verify that recent changes haven’t negatively impacted existing features, end-to-end testing can serve as part of a larger regression testing effort. This ensures that updates don’t “break” other areas of the application that were previously working fine. Here’s a list of tools to help you with regression testing.
- Why: Even small changes can have unintended consequences elsewhere in the system. End-to-end testing checks that new updates don’t cause issues in other areas.
Best Practices for End-to-End Testing
- Write Clear and Concise Test Cases: Before you start testing, you need a plan. Test cases outline the steps of what you’re testing and what the expected outcome is. Clear and concise test cases are crucial because they guide the testing process and help testers know exactly what to do.
- Prioritize Testing Critical User Flows: Not every part of your application needs to be tested in every cycle. Focus on the critical user flows – the key actions that users perform most often and that are essential to the app’s functionality.
- Keep Tests Independent: Each test should be independent and able to run by itself. This means that one test should not rely on the results of another. If one test fails, it should be easy to figure out why without having to go back and fix a previous test.
- Use Data-Driven Testing: Data-driven testing involves testing the same workflow with different sets of input data. This is particularly useful when you need to test how the system handles various types of input, like different usernames, payment methods, or shipping addresses.
- Automate Repetitive Tests: While manual testing is useful, automation can make your life easier by handling repetitive tests, especially for large applications. Automated tests run quickly and can be reused as often as needed, saving time and effort in the long run.
- Test on Different Environments and Devices: End-to-end testing isn’t just about testing on one device or environment. It’s important to test your application across different browsers, devices, and operating systems to make sure it works properly for all users.
- Regularly Update Tests as the Application Evolves: As your application evolves with new features and updates, you need to update your end-to-end tests as well. Outdated tests can give you false confidence and miss new bugs or issues introduced by changes.
Conclusion
Thus, end-to-end testing works by simulating the user’s journey through an entire system, from the very beginning to the very end, to make sure everything is working seamlessly. It makes sure that all components, such as the interface, database, and backend systems, interact correctly with each other. Whether done manually or through automated tools, this type of testing helps catch critical issues and provides a smoother experience for users in the final product.