What Is End to End Testing in Software Testing? Process & Examples
Contemporary software applications depend on innumerable interconnected parts. All of which need to work together seamlessly. From APIs to databases and third parties, the whole system must work collectively. Thus, comprehensive end-to-end testing becomes a must for your software quality.
End-to-end testing validates your application as a whole by simulating real users who utilise the application and check each part from the user interface to back-end databases. End-to-end testing ensures that all three components of an application are working together, which is a key differentiator from unit testing. Testing that is limited to examining individual pieces in isolation, end-to-end testing examines the system as a whole and integrates the three parts as it should.
What Is End to End Testing in Software Testing?
End-to-end testing in software testing refers to the comprehensive validation of your application’s complete workflow by simulating real user applications from beginning to end. The end-to-end testing method verifies integrated pieces and components under real-use conditions and validates the application as a whole.
E2E testing mirrors real-world user scenarios and input and output data. This type of testing also expands upon unit testing and integrated testing. While unit testing and integration testing are limited to testing individual pieces, end-to-end testing validates all pieces in combination and ensures an integrated system is functioning accurately.
Why Modern Applications Need E2E Testing?
Today’s software systems are a collection of complicated architectures, made up of multiple components. Often dealing with microservices, APIs, databases, and multiple third party integrations. When components interact, sequencing may be effective but issues may arise when the components are combined and act together but in sometimes unexpected ways.
It’s this situation that makes E2E testing essential in validating these complex interactions and data flow across systems. These testing strategies verify verification in data flows between all system components, both internal and external. The value of these testing strategies is to surface integration issues prior to impacting end users and business operations.
Modern development processes demand continuous delivery through rapid feedback loops. E2E testing addresses both concern by providing confidence new features or application updates will not degrade existing application functionality. This type of testing supports agile teams in ensuring software quality while moving quickly through their development cycle.
Real-World E2E Testing Example
We will evaluate an online store starting from product search and ending with order confirmation. Tests will execute via the UI search filters, add to cart, checkout, payment and documented email. Finally, database records were validated, with order status correctly updated, before checking both the internal application and external payment gateway.
This example tested many components while passing the data through the many external integrations. This test proved the application worked as anticipated by the end user while navigating the purchase flow. Simulating this end-to-end test reduces the risk of lost orders during production.
5 Benefits of End to End Testing
Checks actual user experiences
E2E tests simulate real user experiences, following the user journey to the end. They show how the app feels in the hands of an actual user. Usability tests are only able to check if an app does what it is meant to do, but E2E tests can find usability annoyances or issues that code checking will not find.
Catches integration errors early
E2E tests check how the modules that make up your app can talk to each other. E2E testing will discover broken data flow, API issues and/or issues with other integration points. Identifying these errors earlier will save your organization time and costs.
Increases test coverage across systems
E2E testing will cover UI, connected integration points or services within the stack, or external services. E2E testing does not replace unit or integration testing; instead, it expands coverage by performing a complete test of the full flow. Any time you test a complete flow, you can be more confident that your critical path of the application is covered.
Increases stability of the system
When executed regularly, E2E tests can improve stability of the application over time. The tests show that changes do not break existing workflows that are critical to the application being functional. Frequent and stable releases that don’t break existing features lead to fewer surprises in production.
Increases confidence to release
Robust E2E tests provide the teams with proof that the core flows of the app work before a release. It also provides a way to demonstrate to stakeholders, teams, and leaders who are impacted by the application that the tests were run successfully. Knowing that the core flows tests pass gives confidence before releasing an application.
Types of End to End Testing
Horizontal Testing
Horizontal testing focuses on validating complete user-facing workflows across your application. This type of testing tests the application from the user perspective and through the various modules and components in the application. It guarantees that every customer experience runs properly from beginning to end.
The horizontal e2e testing simulates actual user behavior patterns & typical scenarios for usage. The teams validate that users can complete their intended tasks without obstruction. This outside-in methodology simulates how real users engage with your software.
Vertical Testing
Vertical testing, on the other hand, takes a technical viewpoint and looks at the layers of the system itself and the backend processes. Users only see the frontend, but testers validate the data movement through the components of the system and its components as a means to ensure the right information is transferred at the right time to the right place.
The vertical e2e testing method checks that data integrity is maintained across all steps in which the system processes data. The teams ensure that services can properly communicate with each other, in addition to proper data processing. This methodology serves as a counterbalance to the horizontal testing to ensure end-to-end testing methodology coverage is complete.
The End to End Testing Process
Test Planning Phase
Test planning starts following the end of integration testing, with the intention that the integration testing is completed and ready to conduct wider scope validation. The teams will define test objectives or claims based on client requirements and the underlying application architecture. The test planning phase will determine what will be tested and how it will be validated.
Test Design Phase
Testing design is the phase where the teams will set up the testing environment to mirror production conditions. The major consideration is setting up an appropriate configuration so that the tests can be run in realistic conditions that reflect actual usage. Risk analysis and usage analysis inform decisions regarding the creation of test cases and automation scripts or tools.
Test Execution Phase
Testing execution consists of executing test scenarios both locally and remotely across environments. Teams monitor the test execution to ensure it is consistent with the objectives established in the original test plan. Automated test cases may be used to augment manual testing in scenarios of greater complexity.
Results Analysis Phase
Results analysis evaluates the outcomes of tests to identify the root causes of failures. Teams evaluate the data from the test suites to determine where and why issues occurred. Those findings are relayed to the development team to determine if the issues can be fixed immediately.
Difference Between UAT and End-to-End Testing
| Basis of Difference | UAT (User Acceptance Testing) | End-to-End Testing (E2E Testing) |
| Purpose | Ensures the software meets business needs and user expectations. | Ensures the entire application works from start to finish across all systems. |
| Focus | Business workflow validation from the end user’s point. | Technical and functional flow across multiple components and integrations. |
| Who Performs It | Actual end users, clients, or business stakeholders. | QA testers or automation engineers. |
| Timing | Conducted at the final stage before product release. | Done after integration testing and before UAT. |
| Scope | Covers only key business scenarios. | Covers full system workflows and all connected components. |
| Environment | Performed in a near-production environment. | Performed in a test environment replicating production. |
| Test Type | High-level, user-centric scenarios. | Detailed scenarios including backend, APIs, and data flows. |
| Goal | To confirm that the software is ready for real use. | To confirm that the entire system works smoothly from end to end. |
| Test Cases | Simple and real use case-based. | Detailed, technical, and system-wide. |
| Defect Reporting | Business-focused issues reported by users. | Technical defects logged by QA teams. |
| Output | Final approval or sign-off for release. | Assurance that the system behaves correctly as a whole. |
5 Best Practices for E2E Testing Success
Concentrate on Critical Paths Only
In your E2E tests, limit your technical engagement to testing only the most critical user journeys.
Rather than attempting to test every possible edge case at this level of testing, rely on unit tests and integration tests for checking edge case requirements in more detail.
Establish a Layered Testing Strategy
Utilize the testing pyramid, including perhaps more unit tests, fewer integration tests, and even fewer E2E tests. Each layer of testing is designed to find different problems, and a healthy mixture of all layers is much better for quality.
Each additional level of tests brings speed and confidence in the quality of your testing.
Use Realistic Test Data
Make the data feel as close as possible to what users are doing in reality.
Finding issues with realistic test data is almost impossible to find using fake test data.
Avoid any real customer/ end-user data as this may lead to privacy and safety issues.
Integrate E2E Tests Into CI/CD Pipelines
CI/CD pipelines allow for engagement tests to run automatically as part of an important step in deployment. This automation can provide valuable, immediate feedback while the code is deployed. A full suite of tests can be run the following night or once a week.
Monitor and Improve Continuously
Keep tabs on failures, slow tests, and flaky tests. Get rid of automating tests that are no longer useful. The more you improve your test suite, the better results you will have for the testing effort you put in over the long term.
Popular End to End Testing Tools
- Katalon Platform
Katalon is a comprehensive platform for testing from start to finish. It allows teams to plan, create, execute, and analyze tests in a single place. It easily creates automated tests for web, mobile, and API tests.
Katalon includes AI features to suggest test cases and generate test data. It also uses auto-maintenance tools to minimize test flakiness. Teams can easily run tests across multiple environments with zero config.
- Selenium Framework
Selenium is an established open-source web test automation tool. It activates browsers that simulate user actions in a realistic way. It supports many programming languages and a variety of automation frameworks.
Selenium is great for cross-browser testing across multiple devices. It gives teams full control of their test setups and infrastructure but requires teams to manage that themselves.
- Cypress Testing Tool
Cypress is a fast, modern testing tool for testing web applications. Cypress runs testing in the browser itself, which increases the accuracy of results. Cypress has built-in debugging, waiting, and updates for tests, and real-time test updates.
Cypress is less flaky than many existing tools and is easy to use for developers. It also works with continuous integration pipelines to automate testing.
- Playwright by Microsoft
Playwright facilitates consistent and reliable end-to-end testing in all modern web browsers. It runs on Chromium, Firefox, and WebKit, providing consistent APIs on every platform. The framework is well qualified to automate complicated user interactions and workflows.
Playwright includes auto waiting, web first assertions and integrated test isolation. It can handle multiple devices, viewports and geolocation testing without any issues.
5 Challenges of E2E Testing
- Complex Environment Setup
Setting up an environment that mirrors reality is challenging, as there are lots of systems, APIs, and third-party tools that are required to work in conjunction.
- High Maintenance
E2E tests tend to break much more often than other tests when changes occur to the UI or workflow, and they require more updates.
- Flaky Tests
Tests may fail randomly due to timing issues, network delays, or unstable environments, leading testers to have less trust in the result.
- Slower Execution Times
E2E tests take more time to run since they run the entire workflow, rather than just testing an isolated function.
- Challenging Debugging
When a test fails, it is difficult to determine the actual cause of the failure since so many moving parts are involved.
Conclusion
End-to-end testing guarantees a perspective of how the entire app is working from the viewpoint of the user. E2E testing shows integration issues, focuses on user experience, and ensures the quality of the software. To get the most value from an end test, use a balanced strategy with some focus.
Frequently Asked Questions
- What is end to end testing software?
End-to-end testing software allows teams to test the different workflows of an application from when the first user action is performed to the final desired system output. It verifies and validates how the entire system behaves throughout the workflow and guarantees that all parts of the application will “work” properly together.
- What is the difference between UAT and end to end testing?
User acceptance testing (UAT) examines whether or not end-users believe that the software meets the business needs from the user perspective; end-to-end testing examines whether or not an entire workflow is functional and working correctly, including the systems that are integrated into the application workflow.
- What does E2E testing verify?
It verifies a complete “workflow”, including, but not limited to, workflows – meaning data flow and APIs, the user interface (UI), the backend, and any third-party applications, libraries, or tools.
It verifies that the system behaves appropriately when operated by a user under real user conditions. It also verifies that the application will be reliable regardless of the path a user takes to get to a desired state.
- What does “end tests” cover?
End tests cover user actions, system interactions, system responses, data transactions, and supporting integrations. End tests also verify frontend subsystems, backend subsystems, services, and databases involved in the user actions. End tests verify a complete real-world situation and workflow.
- What is an example of end to end testing?
Testing an e-commerce checkout process from start to finish exemplifies end-to-end testing. The test validates that product selection, cart management, payment processing, and order confirmation work together. This comprehensive test ensures all integrated components, including databases, APIs, and external services, function correctly.
- Is E2E testing time-consuming?
Yes, E2E testing is time-consuming, as it encompasses many components. E2E tests run subsystems, APIs, databases, and UI flows. Automation helps limit run times, but still may be excessive.
