What Is End-to-End Testing and How Does It Benefit Your Product?

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Software is becoming more functional and multi-layered. Thus, it becomes more complicated to develop and test. The more components we aim to add to a system, the more room for bugs appears. It doesn’t mean that companies should go back to simple solutions. Instead, they can include end-to-end testing in the pool of QA activities.

What Is End-to-End Testing?

Let’s start with an end-to-end testing definition. In simple words, it is a check of a particular user scenario from the beginning to the end. For example:

If we are speaking about an e-commerce platform, an E2E test can check a user’s journey from entering the homepage to paying for the order.
If it’s a video streaming service, a user scenario can start with registration, cover the search, and end with clicking the Play button.

You can remember similar examples from other digital services. With end-to-end testing, QA engineers can ensure that functionality works as intended from the initial interaction and until a user performs an intended action. As you might have already guessed, E2E tests cover several different features that can belong to different layers – UI, API, etc. – and interactions between them.

Long story short, a software tester can see how software behaves when the functionality is ready and assembled.

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Why Do We Need E2E Testing?

E2E testing has a list of benefits for all parties in the development process. QA engineers can focus on the end-user’s perspective and verify a product’s real-world behavior, ensuring it is ready for the market. Decision-makers can see a bigger picture, learning if there are failing scenarios and how they affect end-users.

The key benefits of end-to-end testing are:

Checking business-critical scenarios from the beginning to the end to ensure the correctness of software behavior.
Testing different components, subsystems, and application layers in one iteration.
An opportunity to exercise the business logic of your software before the release.
A strong focus on the end-user’s perspective reduces potential risks and builds confidence in the product.

Of course, creating test cases with real users in mind and building confidence in the end-product are the key values of all the QA activities. E2E tests, however, deal with the close-to-final build, real-live conditions and environments. Even if we’ve tested all the components, subsystems, and workflows individually earlier, end-to-end testing can reveal the bugs that tend to pop up at the seams when everything is supposed to be completed.

When to Use End-to-End Testing?

QA specialists run E2E testing at the late stages of development after all the system components are organized and integrated. If we are talking about the timeline in an SDLC:

First, developers run unit testing, focusing on the smallest individual components of the software.
Then comes integration testing, when QA engineers check the basic functionality after units are combined into features.
Finally, there is system testing, which implies testing the whole application. End-to-end testing is a subset of system testing run at the end.

There’s another aspect for “when” – viability, relevance, or usefulness. As you can suppose, covering all the possible user scenarios would be too time-consuming (if you even can be sure to cover all of them). Thus, a QA team advises focusing on the common behaviors and leaving out rare and unusual scenarios.

End-to-End Testing Cycle

E2E testing comes closer to the end of the QA process. In a Test Plan or Test Strategy document, it will have a dedicated sub-clause with its goal, objectives, approach, test items, resources, and timeframes.

As for the E2E testing process, it usually goes like this:

Planning. A QA team determines the testing tasks and resources.
Test design. The team prepares test cases or checklists.
Testing. When the artifacts are ready, the specialists run tests.
Analysis of the results. The team provides deliverables – checklist, bug reports, or other agreed documents that feature the results of the E2E testing.

After developers fix the bugs, the QA team runs retesting to verify the changes.

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Manual vs Automated End-to-End Testing

Test automation services are known for faster and more accurate results. It can help the team save time and increase efficiency. But as you might already know, the key to smart automation is correctly selected test cases. So do E2E tests fall into this category?

As a rule, end-to-end testing is manual. During this kind of check, QA engineers often work with external interfaces that may be difficult to automate. As a result, end-to-end tests have gained the reputation of being somewhat flaky, slow, and complicated to maintain.

Nevertheless, a lot depends on the particularities of your product. You can always ask the specialists from a software testing company about the viability of E2E automation on the project.

E2E Testing vs System Testing vs Functional Testing

A variety of testing types and methodologies sometimes makes it difficult to distinguish between them. Thus, people often get confused when it comes to telling the differences between end-to-end, system, and functional testing. Here’s a brief cheat sheet that might be helpful:

Differences between end-to-end, system, and functional testing
End-to-End testing	System Testing	Functional testing
A testing methodology, a subset of system testing.	One of the four levels of testing (comes after unit and integration testing, before acceptance testing).	A type of testing that checks software functions.
Covers separate user flows.	Covers functional and non-functional aspects of a product.	Covers functional aspects of a product.
The purpose is to check common scenarios from an end-user’s perspective.	The purpose is to check how all components behave when assembled into a wholesome system.	The purpose is to verify the behavior of product features per requirements specification.
Focuses on business requirements.	Focuses on technical requirements.	Focuses on both technical and business requirements.
Performed in an environment similar to production with real dependencies and network conditions.	Performed on all integrated components of the application.	Performed on a single component or all integrated components of the application.
Understanding the dependencies on third-party systems is essential.	A QA specialist should be familiar with the requirements and have a good understanding of software functionality.

Bottom Line

It is easy to get lost in the QA terminology. Adding E2E testing to the list of the QA activities project teams should keep in mind doesn’t help at all. Nevertheless, each kind of software check has its place in a software development cycle and adds value to product quality.

QA specialists run end-to-end testing at the late stages of the quality assurance cycle. It allows us to see how a product behaves in conditions that are ultimately close to a live setting. By replicating real user scenarios, we get to verify that business-critical workflows run uninterrupted from the beginning till the end. And if they don’t we can show at what point the flow fails.

This type of testing is resource-intensive, but a smart selection of test cases allows increasing the testing efficiency and building confidence in the end-product’s quality.

Inna Feshchuk