Wouldn’t it be a nightmare to be in the developer’s shoes on a Monday morning? You diligently spent the entire last sprint polishing a brand-new feature. You personally coded it, your unit tests confirmed everything was in order, and even your integration tests gave you their green light. You deploy to production with confidence in your work.
However, support tickets are back and forth like a soccer ball.
One customer states, “I can’t check out. The ‘Submit Order’ button is not doing anything,.”
You rush to check the logs. It turns out the problem is not your code. The database is sound. Even the payment gateway is operating correctly. But when combined, they fail. An API response format was changed slightly without your frontend being informed.
This is a good example of the ‘it works on my machine’ paradox. Each of the components could be working fine individually, yet when a user tries to complete an entire workflow, the application crashes. This is where end-to-end testing walks in as the MVP of your quality assurance strategy.
In today’s software development, one broken link in the chain is enough to spoil the user experience, which can result in the loss of customers. This article explains what end-to-end testing is and why it plays a crucial role in minimizing business risk. It also discusses the necessary strategies to develop a strong testing suite that safeguards your company’s good name.
What Does End-to-End Testing Involve?
End-to-end testing (E2E testing) is a method where a software system along with its integration with external interfaces is tested for correctness in all aspects. Its purpose is to test a user flow capable of handling an entire transaction.
Instead of looking inside, E2E testing treats the application as a “black box.” It doesn’t care how the code is written; it cares if the application behaves as expected when a user interacts with it.
Testing Pyramid
To fully comprehend the place of E2E in the context of other types of testing, we need to talk about the “Testing Pyramid.” The pyramid is a metaphor that illustrates different levels of an effective test strategy.
- Unit Testing: They are the foundation of the pyramid. They are the tests of individual components—functions, methods, and classes—in isolation. They are quick, relatively low cost, and very common.
- Integration Testing: These tests form the middle layer in the pyramid. By checking if the various elements fit together they ensure that modules or services can communicate with each other.
- End-to-End Testing: These tests represent the pinnacle of the pyramid. They ensure that the flow of the application down and up from the user interface to the database and back again works correctly.
An Example
Let’s say you have an e-commerce application. A unit test might check whether the “calculate tax” function returns the expected results. An integration test might check whether the shopping cart service can access the inventory database.
However, only the end-to-end test validates the whole customer journey:
- The user does a login.
- They type in “running shoes.”
- They pick one item, and add it to the cart.
- They provide the shipping information.
- They click on the “Pay” button.
- The system generates the order confirmation and sends out an email.
If the payment gateway fails, or the inventory does not get updated after the purchase, the E2E test is marked as unsuccessful. It is through this test that the missing links between unit and integration tests are covered.
Reasons to Adopt an End-to-End Testing Strategy
Developing a comprehensive end-to-end testing strategy means investing time and money. Yet, if a company decides against it, the price to pay will be much higher. Here’s the rationale why it is a must-have for software in the current times.
Guaranteeing Dependability of the Entire System
Not many applications today are standalone monoliths which contain everything inside. They are reliant on a complex mesh of subsystems like internal APIs, third-party authentication (e.g., “Login with Google”), payment processors (Stripe or PayPal), and cloud databases.
Even though you have the power over your code, third-party services are out of your control. If, for example, an external API changes its data structure, your unit tests wouldn’t detect it as they usually mock that data. End-to-end testing is the solution that verifies whether communications between the various components in a live-like setting are correct.
Preserving the User Experience
The fact of the matter is that users are not interested in excellent code, clean architecture, or 100% unit test coverage. What matters to them is whether the application works or not. Are they able to accomplish their task?
What sets E2E tests apart from others is that they check the application from the user’s perspective. E2E tests spot only frontend problems such as a modal window not closing, an unclickable button on mobile, or a loading spinner which never goes away. These issues are the most annoying for users and consequently make them stop using the platform.
Reducing Business Risk
The later a bug is discovered, the more its cost skyrockets. Fixing a bug after production is more than 100 times as expensive as during the design or testing phase, according to the Systems Sciences Institute at IBM.
Besides the financial part (developer hours spent on hotfixes), there is also the cost of lost reputation. It is unlikely that anyone will forgive a banking app after it fails during a transfer or a healthcare portal after it leaks data. It is through E2E testing that such critical failures are caught before they become public, thus serving a security blanket function.
Guide to End-to-End Testing
When the time comes to build an E2E suite, the seemingly overwhelming task becomes manageable once broken down into a few structured steps.
Step 1: Setting up the Environment
You cannot use a developer’s local computer for end-to-end testing. Thus, what you need is a separate staging environment that is as similar to production as possible. Various aspects such as database configuration, network condition, and server settings ought to be identical.
If the production environment runs a certain database version, then the test environment must also run this version. In case there is no parity between the two environments, you will be getting false positives, which means that the tests pass in the staging environment but fail after deployment to production.
Step 2: Test Cases Design
It is unnecessary to “test every single button click.” Instead, you can concentrate on user personas and core workflows.
- Normal or Happy Scenario: It depicts the user path with everything functioning smoothly. The user logs in, purchases the item, and logs out.
- Alternative or Exception Scenario: It is meant to describe the situation when something goes wrong. The user uses an incorrect password. The card payment is refused. The internet disconnects.
Tests for both positive and negative situations force an application to be developed in such a way that it does not crash when presented with errors but rather handles them properly.
Step 3: Test Execution and Analysis
Only regular execution can make tests effective. Failure of tests demands immediate attention and therefore must be analysed. You also have to figure out whether the problem lies in the system or if the failure is due to a flaky test.
Proper logging of results accelerates the process of investigation and helps developers quickly find the cause. By doing this, the developers are equipped to turn the red “FAIL” into a ticket that can be resolved.
Mastering the Process: Best Practices
If you want to keep your testing suite efficient and reliable, you ought to follow the best practices outlined below.
Strategic Automation
Automatically running tests gives off the impression that all is going right. Usually, it isn’t. There is a hierarchy to the types of automated testing. Also, automated tests cannot perform all the functions human testers can.
Mostly, automated testing focuses on the repetitive and high-value user paths—the so-called “critical business logic.” Checking out is a business-critical function. Automation of this part is a must. However, small things on the UI such as the misaligned footer link on the About page can be verified manually or through a visual regression tool, for instance.
Continuous Integration (CI/CD)
Always treat testing as a natural step in the development process, not as an afterthought. By embedding an end-to-end testing system into a Continuous Integration/Continuous Deployment (CI/CD) pipeline, you make sure that any time new code is checked in, the critical workflows are validated.
With automation of regression testing you get an added bonus. It prevents scenarios where the feature added by Developer A breaks the login feature originally created by Developer B 3 months ago.
Regular Maintenance
The software is constantly evolving and your tests have to reflect those changes. After revising the UI flow of the signup page, if you don’t update the E2E test, it will register failure even when the signup feature is working correctly.
Tests that are no longer relevant lead to “test fatigue.” Developers will stop paying attention to the true failures after many times seeing red and thinking “oh, these are just false alarms.” Weekly or sprint review and update of the E2E test cases ought to be part of the team routine.
Setbacks and Remediation: Common Problems with E2E Testing and How to Solve Them
Putting end-to-end testing into practice is not trouble-free. In cases where a team comes up against a problem, here are some of the solutions for the most frequently faced issues.
Environment Complexity
To be able to do full tests, you need an environment with all services such as databases, microservices, and third-party APIs. Data management, that is, ensuring that the user exists in the database prior to testing the login feature, is a common source of frustration.
Resolution: Containerizing with Docker helps you to create a fresh, identical environment every time you run a test. You can automate the loading of seed data into the database prior to the test and make sure it is cleared once the test ends.
Flaky Test Management
Flakiness is the bane of confidence. Tests that become flaky fail seemingly out of the blue, though with no changes having been made to the code. It could be, for example, that the page took 500ms longer to load.
Resolution: Eliminate fixed “sleep” timers like “wait 5 seconds”. Favour the usage of smart waits that some modern testing frameworks come equipped with, e.g., instructing the test to “wait only till element X is visible” rather than waiting for an arbitrary amount of time. This enhances the robustness of your tests towards network lag.
Time Taken for Test Execution
Since E2E tests involve a browser and a network, they are slower than unit tests. As more tests get added to your suite, feedback loops start to get longer.
Resolution: Make tests run at the same time. Instead of running 100 tests in a sequence, run 10 tests at a time in 10 different containers. Also, develop a so-called “smoke test” (a very small set of tests that runs on every commit) and leave the full, heavy regression suite for nightly runs.
End-to-End Testing: Top Pick Tools
There is no shortage of great tools on the market that make the testing process smoother.
- Selenium: The granddaddy of them all. This tool supports nearly any browser and language imaginable. Being very versatile, it also demands lots of coding and maintenance.
- Cypress: The darling of web developers. It is embedded in the browser which makes it super fast and easy to debug. It is great for modern web apps but one drawback is the limited handling of multiple browser tabs.
- Playwright: One of the latest releases from Microsoft. Not only is it fast and reliable, but it also supports multiple browsers (Chromium, Firefox, WebKit). A very neat feature is that it mitigates test flakiness by auto-waiting for elements.
Solutions such as these have allowed Netflix and Spotify to come out with very strong strategies. Through faith in their automated suites, they are able to release code thousands of times a day without worrying about disrupting the user experience.
Conclusion
Before software reaches its user, end-to-end testing acts as a final safety net. It serves as a link between technical code correctness and actual user satisfaction.
Setting up these tests requires time and effort but the return on investment is well worth it. Stability of systems, reputation protection and significant long-term cost savings by bug catching at an early stage are some of the fruits.
Have a look at your QA process today. Solely depending on unit tests to find bugs would mean that you are leaving your critical workflows vulnerable. It is time to start charting user journeys and implementing coverage at the top level to be sure software works not only in theory, but also in practice.
