What is end to end testing?

End to end testing (E2E testing) is a software testing technique that evaluates the functionality and performance of an application by testing it from start to finish, under real-world conditions. By simulating the live settings, E2E testing validates the behavior of not only the overall application but also its sub-systems from the end user's perspective.

As software becomes more complex, applications can consist of numerous intricate components, including UI and API layers, external databases, networks, or third-party integrations. One component’s malfunction can lead to the failure of the whole system. This calls for a comprehensive testing approach to ensure the entire workflow functions accurately, from UI to API levels. 

With end to end testing, all the system’s dependencies are verified in terms of functionality, stability, and security.

Read more: What is End-to-End (E2E) Testing? All You Need to Know

How does end to end testing work?

End to end testing is typically performed after integration testing - which checks the interaction between multiple units - and before the application is deployed.

To make sure the software runs optimally under real user scenarios, end to end testing involves setting up a test environment that mirrors closely to the production one, including hardware, software, and network configurations.

Similar to other software tests, end to end testing also involves:

• Requirements planning: Analyze the test needs to plan test scenarios and work products that will achieve the test objectives.
• System design: Describe the components, tools, testing methodologies, and metrics utilized in the system, along with the responsibilities of the team members involved.
• Test infrastructure development: Test case preparation and configure the hardware and software environment.
• Test design: Use traceability to check the completeness and consistency of test cases with respect to the defined test conditions.
• Test execution: During the test execution phase, monitor test progress for completeness and consistency with the test objectives, test strategy, and test plan.
• Measurement and analysis: Review test results to determine the root cause of the issue and identify corrective actions. Collect information to generate accurate reporting and evaluation against exit criteria.

Read More: Software Testing: A Complete Guide

Why do we perform end to end testing?

Modern software systems are built with various components, making the entire infrastructure complex and unpredictable. Enterprise-grade applications can have hundreds of dependencies and components. 

Online banking systems, for example, are connected with multiple libraries, databases, 3rd party services to support existing features such as user authentication, account management, transaction processing, and reporting. These units may work fine individually, but when combined, there is a potential for arising conflicts. A small failure in the password database can disrupt user verification, leading to a cascading effect on the whole application.

To ensure the final quality, it is necessary to simulate the user journey from simple to complex. This is where end-to-end testing becomes crucial in ensuring that all moving parts of the application work together seamlessly and the final product meets the user's expectations.

Executed properly, end to end is widely practiced for its substantial benefits:

• A broader range of test coverage: End to end testing goes beyond unit testing and integration testing by verifying all software components, from the API to UI level. 
• Reduced regression testing effort: Once end to end testing has been successfully executed, these tests following user flow will be automatically run when there are changes, allowing regression testing to focus on affected components.
• Optimized customer experience: Running tests based on end users’ behavior makes sure that the application operates smoothly and provides a positive experience.

Automated end to end testing software: Key features

Like any test automation, selecting the right E2E testing tool lies at the center of a project’s success. While there are numerous options in the market, from open-source to commercial, an ideal test automation solution should consist of the following features:

• Cross-platform testing: The software should be able to test applications on different OSs, browsers, and devices to ensure their compatibility across environments.
• Low-code test design: End to end testing is a joint effort of multiple stakeholders. The chosen platform should enable flexibility and collaboration between members of different coding expertise. Developers are able to build custom keywords while QA teams can simply drag and drop to create tests. 
• Comprehensive functionality: The ideal tool should support features that cover the whole end-to-end testing lifecycle, from test planning to results analysis. 
• Extensive integration: Integrations with popular CI/CD and DevOps tools like Jira, Jenkins, or Docker enables simpler collaboration and streamlined testing workflow.     

Overviews of the 5 best automated end to end testing tools

#1 Katalon - Software quality management platform

The Katalon Platform is an end-to-end test automation solution that supports automated tests at both UI and API layers with AI-powered testing features, simplifying these processes, and expanding test coverage while reducing cost and effort.

Katalon allows QA teams to author web, mobile, and desktop automated tests, execute those tests on multiple environments, maintain them, and analyze results, all in one unified platform.

With features such as Recorder and Script mode, beginners can record and playback actions on the UI, drag-and-drop keywords, or import what the developers have prepared. Meanwhile, expert programmers can still do development testing by scripting in Java/Groovy for complex scenarios or building custom keywords.

Take the example of creating tests for a registration page. Other than the default package of inbuilt keywords such as Submit, Close Window, Click Image, etc. Users can also custom keywords such as CheckDropdownListElementExist to verify if the software shows the correct dropdown values.

Feature highlights:

• Compatibility testing: local and cloud browsers, devices, and operating systems are available to run cross-platform API, end-to-end, and regression test suites in parallel.
• Easy maintenance: An object repository is built-in to store and access all of your UI elements, objects, and locators. Easily update tests when the application's UI changes. 
• Requirements traceability: Native integrations with Jira, qTest, and Xray.
• API testing with REST, GraphQL, and SOAP: Supports REST, SOAP/1.1 and SOAP/1.2 requests. Tests can be imported from Swagger, Postman, and WSDL.

#2 Autify: No-code AI-powered end to end testing tool

Autify is a test automation tool for web and mobile applications. You can automate E2E tests for applications by recording their interactions with its Chrome extension, then run these tests on various systems, including Windows, Linux, and Mac, as well as a range of web and mobile browsers. Its features include:

• Smart Test Automation: Uses AI and machine learning algorithms to automatically detect changes to the UI and adjust the test cases accordingly.
• Visual Test Editor: Clicking and dragging elements on the screen to create tests. 
• Integrations: Integrates with CI/CD tools such as CircleCI, Jenkins, and Gitlab.
• Test Result Analysis: Test reports and analytics, including screenshots and videos.

#3 LambdaTest: Cross-platform testing across devices and operating systems

LambdaTest is a cloud-based cross-browser testing platform that allows you to perform end-to-end testing of your web applications. It provides access to over 2000 real browsers and operating system combinations, allowing you to test your web application's functionality, user interface, and performance in different environments.

Feature highlights:

• Responsive testing: LT Browser checks the responsiveness of websites on major devices and viewports.
• Visual cross-browser testing: Auto-generated full-page screenshots of web pages
• Test locally hosted websites: Validate pages with Lambda Tunnel–an SSH-based integration tunnel

#4 TestComplete: Automated UI testing tool 

TestComplete by SmartBear is a powerful automated testing tool that builds and runs functional UI tests for desktop and web apps. Tests can be recorded, scripted, or manually created with keyword-driven operations and used for automated playback and error logging.

Built on an open COM-based architecture, TestComplete supports and integrates different tools and applications such as Jenkins, Git, Atlassian Jira, Atlassian Bamboo, Subversion, Mozilla Bugzilla.

#5 testRigor: Customizing complex test cases

testRigor enables automated testing through simple plain commands, making it ideal for manual QA testers with limited programming knowledge. Its AI-powered automation script can enhance test coverage with minimal effort required. Additionally, testRigor allows you to create customized test cases for complex scenarios.

Feature highlights:

• Ability to generate tests that simulate how real-world users interact with your application.
• Creates codeless cross-platform tests for web, native, and hybrid mobile applications.
• Seamlessly integrates with test case management systems.

Overviews of the 5 best end to end testing frameworks

#1 Selenium: Web automated testing

Selenium is a suite of libraries and extensions that are used to build a framework that enables web browser automation.  It offers easy interaction with HTML elements, giving you the flexibility to customize your tests.

Feature highlights:

• Locate relative locators: finds elements using above, below, toLeftOf, toRightOf, and near
• CDP access: uses Chrome DevTools APIs to mock network requests and responses, and debug tests on the fly
• Smart object detection: findElement() method to find locators like ID, Name, ClassName, TagName, LinkText, Partial Link Text, XPath, and CSS
• WindowHandlers multi-window/tab: getWindowHandle and getWindowHandles methods to open/close browser tabs

#2 Cypress: Web UI end to end testing

Cypress is a front-end test automation tool that allows you to debug the front-end UI of your web apps. With Mocha as the underlying framework, Cypress looks mainly at solving waits and time issues present in Selenium. Cypress provides a built-in debugging feature and allows you to set up automatic retries and waits. 

Feature highlights:

• Automatic waits: no async/await functions are needed to wait for commands and assertions
• Cross-browser: support Firefox, Edge, and Electron browsers
• Dashboard service: parallel and cross-platform execution, load balancing, and quality insights
• CI/CD integration: GitHub Actions, GitLab CI, CircleCI, Bitbucket Pipelines, and AWS CodeBuild.
• Snapshots and videos: review previous states of the DOM to figure out what went wrong 

Read More: Katalon vs Cypress: A Detailed Comparison
 

#3 Nightwatch.js

Nightwatch.js is an open-source, browser automation framework that is built on top of the Node.js platform. It provides a simple yet powerful syntax for automating end-to-end testing of web applications, with support for various web drivers and frameworks like Selenium, ChromeDriver, and FirefoxDriver.

Features highlights:

• Parallel testing: Run tests in parallel across multiple environments, saving time and increasing efficiency.
• Built-in test runner: Built-in test runner that enables you to execute tests and generate reports with a single command.
• Page Object Model: Write tests that are more maintainable and scalable.
• Integration: Selenium, Sauce Labs, BrowserStack, and more.

#4 Puppeteer

Puppeteer is a new framework that allows testers to perform headless browser testing of Google Chrome. It lets you run headless Chrome in Node.js to perform a majority of tasks such as handling requests and responses, locating elements, network traffic, and so on.

• Screenshots and PDF generation: Generate screenshots and PDFs of web pages, which is useful for debugging, testing, and generating reports.
• Network interception: Intercept and modify network requests, which is useful for testing web applications and debugging network issues.
• Element selection and manipulation: A range of functions for selecting and manipulating HTML elements on a page, helping automate complex user interactions.
• Modern web technologies: Puppeteer supports modern web technologies such as ES6, CSS Grid, and Web Components.

#4 QA Wolf

QA Wolf is a cloud-based E2E test framework for testing teams of all expertise levels. It is a great fit for companies that want to free up their QA team from test maintenance. Some main features of QA wolf are:

• No installation or setup is required to get started.
• Reproduces failures faster with logs, recorded videos, and highlighted lines of code leading to failure
• Fix and maintain tests directly in the browser
• Easy collaboration with team members on creating and maintaining tests

FAQs

What is an end to end testing example?

Consider a scenario of a health application where a user logs in, books an appointment, and receives a confirmation.

Following this user flow, an end-to-end test for this scenario could include the following verification:

• Verifying the user can successfully log into their account and schedule an appointment.
• Testing whether the appointment confirmation is sent to the user and contains the correct doctor's contact details.
• The doctor can update the user's medical record during the appointment and that the information is accurately recorded.
• The user is notified of the updated record and is able to view it through the application.

Sample WebUI tests project (Healthcare sample) in Katalon Studio | Katalon Docs

Which tool/framework is mostly used for end to end testing?

From open-source frameworks to paid tools, there’s an array of choices available. There are many popular frameworks such as Selenium or Cypress. However, whichever framework you choose, you will end up spending a significant amount of resources on test infrastructure unless you adopt a managed test automation or software quality platform.

Katalon is best when teams don’t want to deal with the hassle of building testing frameworks. Katalon is the complete solution for web, mobile, and desktop testing. Without having to go from tool to tool for different testing types and purposes, you get a full-fledged testing workspace to automate testing for digital products.’

Read more: From open source to Katalon | Streamline your test automation journey

Who will perform end to end testing? 

End-to-end (E2E) testing is typically performed by a dedicated testing team or quality assurance (QA) team within an organization. This team may include specialized E2E testers, manual testers, automation engineers, and QA analysts.

E2E testing may also involve collaboration with other teams within the organization, such as software development teams, business analysts, and product owners. This collaboration helps ensure that the testing process aligns with the overall development objectives and the system meets the business requirements.

End to end vs unit testing

End-to-end (E2E) testing and unit testing are two different types of testing that serve different purposes.

While unit testing focuses on testing individual units of code in isolation, E2E testing verifies the entire system. Unit testing is a type of testing that focuses on testing individual units of code, such as functions or methods. The goal of unit testing is to catch defects early in the development process, by verifying that each individual unit of code works as expected.

End to end API vs. UI testing: What's the difference?

API Testing and UI Testing are essential in providing a smooth user experience, but they test different aspects of the application. API testing ensures that the API can handle different types of requests and responses. For example, the payment processing API of a website must be functional when a customer purchase an item. Meanwhile, UI testing typically involves various user interactions such as button clicks, form submissions, and navigation. 

Is end-to-end testing black box?

Yes, end-to-end testing is a type of black-box testing that focuses on testing the entire system, without looking at the internal components of the system.

In black box testing, testers only interact with the software through its UI or API and evaluate their behavior. White box testing, on the other hand, gives testers access to the internal workings of the AUT, including its source code, architecture, and design.

Are E2E and integration testing the same?

End-to-end (E2E) testing and integration testing are not the same, although they are related and can be complementary.

While integration testing focuses on the interactions between individual components, E2E testing verifies the entire system, including the user interface, data flow, and external integrations.