In short: End-to-end (E2E) testing simulates a real user journey to validate an application as a whole, from the user interface to databases and third-party services. It detects issues that unit tests miss. This guide explains what E2E testing is, its types and methods, its benefits, and how to implement it in five steps, from choosing a tool to analyzing the results.
For development teams, software testing is an essential practice that ensures the quality and functionality of applications before they reach end users. End-to-end (E2E) testing is an approach that simulates real-world user experiences to validate an entire system.
In this article, we'll explain what E2E tests are, why they're important, and how you can implement them effectively in your software projects.
What is e2e testing?
End-to-end (E2E) testing is a software testing methodology that verifies the proper functioning of a software product throughout the entire process, ensuring that all components of a system can operate in real-world scenarios.
e2e testing focuses on the user's perspective, enabling QA teams to identify software dependencies while validating the system under test, its data integrity, and its integrations.
Unlike unit or integration tests, which verify specific parts of the code, E2E tests simulate real-world usage scenarios to evaluate the application as a whole.
Types of End-to-End Testing
1. Horizontal end-to-end testing
The horizontal end-to-end test covers the entire application.
A single test workflow can span multiple subsystems. In an e-commerce web application, for example, horizontal end-to-end testing may include:
- Logging in to a profile
- Using the search and navigation features
- Adding an item to the cart
- Saving the article
- Purchasing an item
- Entering shipping and credit card information
- Purchase Confirmation
- Disconnection
2. Vertical end-to-end test
Vertical end-to-end testing breaks the application down into layers that you can test individually, and often precedes horizontal end-to-end testing.
Performing vertical end-to-end tests with UI subsystems allows you to systematically identify and fix bugs that may be found in each component.
Methods of Execution
Manual end-to-end tests
By providing a general understanding of what works and what doesn't when writing a test plan, manual end-to-end (e2e) tests help in the early stages of the e2e testing process.
They enable testers to identify test cases based on real-world scenarios so that they can be automated later.
Automated end-to-end tests
Since a single action in a user interface can trigger many other actions, automated testing is crucial for thoroughly executing end-to-end tests.
End-to-end (e2e) test automation allows bugs to be detected more quickly and consistently because the entire codebase is verified against test cases every time new code is added.
e2e testing – the benefits
The key benefits of e2e testing:
- Help teams expand their test coverage by adding more detailed test cases.
- Ensures application performance by running test cases based on end-user behavior.
- Helps teams reduce time to market by automating critical user flows.
Implementation of End-to-End Testing
When it comes to implementing end-to-end (e2e) tests, the process is generally as follows:
1. Test Planning
Before getting started, it is essential to clearly define the objectives of the end-to-end (e2e) tests:
Identifying Critical Scenarios: Determine the application's key features.
Defining the Conditions for Success: Establishing Clear Criteria.
This step helps you understand the requirements of the system as a whole, including the interactions between its various components.
2. Selecting an end-to-end (e2e) testing tool
Although manual end-to-end (e2e) testing can be used to identify test cases, with today's increasingly complex systems, it is necessary to use an automated testing tool.
This automation ensures that tests are run consistently and reliably as part of the deployment process, helping to identify issues early and continuously improve software quality.
Examples of tools for end-to-end testing include:
- Mr Suricate
- Selenium
- Cypress
- Playwright
- Appium
- BrowserStack
- Katalon Studio
3. Designing Test Cases
The next step is to design test cases that cover all of the system's key features by simulating real-world usage scenarios.
For example, some scenarios might include:
Forms and Interactions: Validate forms, buttons, and other interactive elements.
End-to-End Transactions: Simulate complete transactions, such as purchases or reservations.
This step involves creating detailed test scripts that include specific instructions on what needs to be verified at each stage of the process, as well as the expected results.
It is also important to consider incorporating validation checks to ensure that data is exchanged correctly between the various components of the system.
4. Conducting the Tests
Run E2E tests in an environment that most closely resembles the production environment in order to:
Detecting anomalies: Identifying and fixing bugs before deployment to production.
Validate performance: Ensure that the application runs smoothly under load and with real data.
5. Analysis of the Results
Once the tests have been run, the next step is to analyze the results to document the bugs found and track their resolution, as well as to ensure the continuous improvement of development and testing processes.
Best Practices for End-to-End (E2E) Testing
Perform a second test: If a problem or defect is found, the data is recorded and analyzed to determine the cause of the problem; the problem is then corrected, and the system is tested again.
Track the data flow: Track the data flow between systems to identify dependencies.
Follow a specific testing order: Unit and integration tests should be performed first to fix the most obvious issues. Each component of the system must also be tested end-to-end.
Prioritize the user experience: End-to-end (E2E) tests should be designed with users in mind and should focus on features that are most likely to cause significant issues.
Mr Suricate No-Code End-to-End Testing
By conducting E2E testing methodically and using the right tools, companies can ensure that user journeys work flawlessly in real-world scenarios.
The no-code SaaS solution Mr Suricate a wide range of automated tests to help you manage your acceptance testing and provide your users with the best possible experience.
Gain control over your applications and detect bugs in real-time across your websites, applications, and APIs by replicating user journeys at regular intervals.
FAQ
What is end-to-end (E2E) testing?
This test simulates a complete, end-to-end user journey to verify that the entire system works together—including the interface, back end, database, and third-party services. It validates the application just as a real user would.
What is the difference between end-to-end testing and unit testing?
Unit testing verifies an isolated component of the code; E2E testing validates an entire flow through all components. Unit testing detects local bugs, while E2E testing detects integration failures that would otherwise go unnoticed.
How do you set up E2E tests?
Plan the critical workflows, choose a suitable tool (ideally a no-code tool to speed things up), design the test cases, run them regularly, and analyze the results. Automation allows you to replay them with every deployment.
Further Reading
To see the solution in action, check out our end-to-end testing.
Learn More: The Glossary of Automated Testing.
