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January 3, 2023

End-to-End Testing: The Ultimate Guide

Alex Husar
Blog > Test Automation
End-to-End Testing: The Ultimate Guide

Software testing is a crucial step before releasing a product. With so many approaches to testing, end-to-end testing (E2E testing) may appear as the most time- and resource-consuming method, but it may be the most significant. It ensures software quality and creates confidence in the entire application.

How does this approach differ from the rest? This methodology is essential for checking the software’s usability from the user’s perspective. How would a customer behave, where would they click, and what do they expect?

End-to-end testing aims to ensure that all components work together to perform a particular function. The tester simulates an actual user interacting with the application with various inputs and expected outputs in mind. All the steps during the testing process imitate a real-world scenario and guarantee a satisfactory user experience. As a result, users can browse well-built PWA eCommerce sites, native apps, and SaaS products.

This post will examine end-to-end testing and the steps required to initiate and complete any E2E test.

What is end-to-end testing?

End-to-end testing, or E2E testing, is the process of evaluating a piece of software from beginning to end in the manner in which actual users will use it. For example, the tester may access a website from a desktop or mobile device, add a product to the cart, open the cart, and purchase. The goal is to run the application along with all its dependencies, including the database, third-party services, metrics, logging, etc., regardless of the software type. E2E testing is most often executed after completing functional and system testing.

Suppose you want to test a web application. You open a browser, type in the needed link or request, use the application as intended, and see how it behaves. You can also employ this method to check a desktop application or API, making calls like actual users.

Why do you need to perform end-to-end testing?

Image credit: Freepik

Although end-to-end testing might seem comprehensive, you should combine it with several other testing techniques to build a solid continuous integration process. Think about the following test types:

  • unit testing, which requires every system component to function as intended;
  • functional testing, ensuring that the system responds appropriately to a specific input;
  • integration testing, combining and evaluating the various software modules as a whole.

However, having these tests in place doesn’t exclude E2E testing. End-to-end testing, which concentrates on the entire user workflow, differs from the tests discussed above. It is essential for testing overall functionality and numerous systems.

end-to-end testing pyramid
Image credit: Testbytes

You may employ the unit test at the lowest level, evaluating a small routine written by programmers. These small routines, or features, form the entire application and are necessary for receiving fast feedback.

To test how these components work together, you run integration tests. Integration tests involve using two or more elements in a test environment, with the outcome being validated. However, even if all of these tests pass without a hitch, there may still be errors or unfulfilled criteria. End-to-end testing is useful in this situation.

To begin with, unit and integration tests don’t include the user interface (UI) if you have one. Only an end-to-end test can answer these questions:

  • How well-organized is the user interface?
  • Does it include all the required components?
  • Will the user be able to accomplish their goals?

Modern software has numerous moving parts, making end-to-end testing essential. For example, servers may affect how apps perform, settings must be set up correctly, and external dependencies may affect the application behavior. Separate component testing will only partially address this.

End-to-end testing is popular due to the reasons such as:

  • increases test coverage by allowing teams to incorporate more specific test cases compared to the unit and functional testing;
  • runs the test cases depending on the end user’s potential actions to make the application operate properly;
  • allows release teams to automate crucial user pathways, which helps them decrease time to market;
  • lowers the overall cost of developing and maintaining the product by speeding up software testing;
  • helps find issues predictably and consistently.

How do end-to-end tests work? An explanation of the testing life cycle

stages of successful end-to-end testing

End-to-end testing uses test suites with numerous test cases to track the flow of the software system and its supporting systems and find points where the flow is interrupted, leading to errors. It involves the following four stages:

1. Test planning

At this point, the test team plans and develops the software testing project. The specialists consider the following questions:

  • what will impact user functionality;
  • how they will gauge test progress;
  • how many enterprise resources they need.

The project’s QA team also assigns specialists and other resources to meet the predefined requirements.

2. Test design and test case development

To create test cases that cover all necessary functionality, testing teams approach applications from the user’s perspective, considering the following factors:

  • sequence;
  • data conditions;
  • timing.

The preparation of all test cases by QA teams should consider actual usage scenarios. The testing process should ensure software quality, and each test case should play a role in that process.

3. Performing a test case

The actual process can start after the QA team has created test suites with solid cases and guaranteed enough coverage. Testers put every case under different circumstances on various platforms and devices, including smartphones and tablets with multiple operating systems. They test the entire software system, including its associated subsystems, from beginning to end.

Some test cases will fail as the testers execute them. When it happens, the developer investigates the problematic code or documents the unsuccessful attempt to meet the functionality requirements. The test team corrects the code or modifies other aspects of the program and repeats the test. QA teams keep doing this until every test passes.

4. Evaluation of test results

Reviewing the outcomes of all test cases is crucial to identify significant risk factors and software flaws. Reporting on the open and closed defect status is one of the test results analysis’s components.

Manual E2E testing vs. automated E2E testing: What to choose

Starting with end-to-end testing may seem unclear. That’s why many businesses choose manual testing for new features and stop there. However, it may lead to undetected bugs in previously functional components. Plus, manual testing will become harder and more time-consuming with the growth of the project and the introduction of new functionality.

manual vs automated end to end testing

It’s particularly true when testing user interfaces because a single action in a user interface may result in different behaviors. That’s where test automation comes into play. Let’s compare the two end-to-end testing types side by side.

To Sum Up

We’ve looked at what end-to-end testing is and why it’s important. End-to-end testing is an integral part of the testing pyramid, along with unit and integration tests. Any organization will profit from incorporating it into its entire testing plan, especially when employing automation testing. But it doesn’t mean you should focus only on automated end-to-end testing. Manual testing is still a good starting point and a solid base for developing automated tests.

Automation, in turn, saves time, prevents issues, and lets your team focus on what they do best: developing apps. To summarize, integrate end-to-end tests or hire experts to make sure your end-to-end test strategy works.

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Alex Husar

About the author

Alex Husar

Alex Husar is a web developer and CTO at Onilab, a full-service eCommerce agency. He graduated from the Czech Technical University and has been working at Onilab for nearly 10 years. This experience helped him become a pro in building PWAs, Magento migration, and Salesforce development. Alex is dedicated to improving his skills, finding answers to tough questions, and sharing insights with the team and readers.

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