Successful software and application development often requires tight integration with DevOps and managed services. Because teams must maintain and follow continuous integration and continuous deployment (CI/CD) practices, testing before delivery is critical. End-to-end (E2E) testing validates the entire software workflow, ensuring software functions as expected in real-world scenarios. This reduces risks and errors, providing teams with confidence both before and after production, while also ensuring a seamless application experience for end-users.
End-to-end testing is especially crucial in today’s hybrid environments, which encompass an organization’s internal platforms and cloud services, including storage, APIs, and third-party tools.
What is end-to-end (E2E) testing?
Software testing evaluates a software product or application to identify errors, ensure the software functions correctly, securely, and efficiently, and determine if it meets user expectations and requirements. Testing can be further divided into the following categories:
Functional testing verifies that functionality meets the specified requirements.
Non-functional testing evaluates performance, security, usability, compatibility, and reliability.
Other types of testing include testing API functionality, mobile application testing, automated testing that uses tools and scripts to execute test cases, exploratory testing outside use cases and expected behavior, and back-end testing that focuses on back-end operations, connectivity, and security.
E2E testing is a software testing methodology that evaluates the complete functionality and data flow of an application or software. A software application can be composed of subsystems or services that are implemented as a complete product or service. E2E testing verifies the entire application by testing all components and integrations with other systems, services, data sources, and APIs.
Why is end-to-end testing important?
E2E testing is crucial for today’s tightly integrated software delivery processes. Development, DevOps, managed services, and other teams depend on E2E testing before an application’s release to production environments for several important reasons:
User confidence: E2E testing verifies critical business flows work as intended. Users rely on practical and operational software to meet their needs, and a crucial error or operational defect can force a rollback to a previous version or cause an application to stop functioning as intended.
Integration validation: E2E integration testing ensures multiple modules and services are securely and reliably integrated with the application. Validated testing results promote confidence that an application and its components are performing as expected.
Regression prevention: E2E regression testing identifies unintended disruptions after updates or new features are added. If errors go unnoticed or unexpected, they can lead to issues such as system failure, data loss, or emergency rollbacks to earlier versions.
Risk reduction: E2E risk testing identifies defects that individual unit tests might miss. By testing the entire software application, E2E testing reduces risk by detecting errors from connected sources or components, security or access errors (from wrong or expired credentials), or a failure to test against real-world conditions.
Business alignment: E2E testing confirms that software delivers value aligned with real-world use cases. Users want software that meets their expectations, follows business plans, and has verifiable test results before general release.
How end-to-end testing works
E2E testing is accomplished with a well-defined strategy. Human testing can perform E2E testing through pre-built unit tests, scripts, and programming, but it can be time-consuming. Automated testing, handled via scripting tools and implemented through pipelines, is the most effective use of time and effort. Other steps to consider when implementing E2E testing include:
- Test design: For this step, user journeys or business processes (for example, account creation or checkout) that require testing should be mapped out and assigned. Test design should consider whether tests should focus on horizontal or vertical testing (or a combination of both), as described in the following bullets.
Horizontal testing follows the user journey or business process from one phase to the next. For example, this process involves searching for and finding a product through the user interface (UI), connecting to the database, placing an order, verifying the order, and completing the checkout process.
Vertical testing tests the layers of an application’s architecture. A vertical test might include the UI using search and find functionality, extending to connect to the database source, placing an order stored in the session, verifying the order stored in the session, and then completing checkout through a third-party service.
Environment setup: For E2E testing, environments must reflect staging or production conditions that mirror real-world scenarios. Ignoring or bypassing this stage can result in errors due to differences between development and production environments.
Execution: E2E testing routines can use scripting for interfaces, APIs, and integrated services that connect to the application.
Validation: During E2E testing, teams should verify outputs against expected outcomes. For example, an output indicated as a specific currency format in design and requirements documents should be presented in the same currency format in the test results.
Reporting: During this phase, testing outcomes should be documented, and any error reports flagged for review, approval, or mitigation. To enhance observability and reporting, E2E testing ought to be incorporated into CI/CD pipelines, enabling continuous monitoring.
What are the benefits of end-to-end testing?
E2E testing offers several advantages. This includes presenting real-world user experiences to detect issues early, confirming that all integrated components function smoothly together, and enhancing user satisfaction by meeting expectations. For an improved user experience, end-to-end testing reduces production errors by catching bugs or inconsistent output during development and identifying performance bottlenecks. For specific teams, the benefits of E2E testing include:
DevOps: Applying E2E testing processes can validate complete application workflows before implementing an application in production environments. Validation can help reduce errors that require a rollback to previous versions and reduce error reporting.
Site reliability engineering: E2E testing provides confidence to teams that their applications ensure business-critical paths are functioning correctly.
Quality-assurance (QA) teams: E2E testing benefits QA by identifying environment-specific and external service or API connectivity issues before and after release.
Front-end engineers and mobile developers: E2E testing ensures application performance is stable across various devices, browsers, and operating systems.
Use case scenarios for end-to-end testing
Examples of use cases for E2E testing include:
E-commerce checkout flow: E2E tests should encompass application functionality, data sources, and connected services from product selection to payment confirmation. These tests should include mobile and web-based versions of the application.
User authentication: E2E tests should include the collection and handling of the user login form, two-factor authentication processes, and session management within the application.
Data-integrity checks: E2E tests should ensure information passes correctly through the UI, APIs, and databases.
Cross-system workflows: E2E testing of integrations for applications with external services (for example, payment gateways, messaging systems, and information lookups) verifies connective points for potential errors or failures.
Common implementation challenges for end-to-end testing
E2E testing can be difficult to implement and maintain. Some of the challenges users could face include:
**Complexity: E2E tests can be challenging to design for large systems. E2E testing requires a fully functional environment that closely matches production, including all integrated services, databases, and external APIs. Setting up and maintaining these environments can be complicated and time-consuming, requiring careful coordination of multiple components.
**Test fragility: UI and integration changes often cause tests to break. E2E tests are prone to unpredictability, meaning they can pass or fail inconsistently without any modifications to the code. This can be caused by unstable network conditions, asynchronous operations, timing issues, or external dependencies, resulting in unreliable results and reducing trust in the testing process.
**Execution time: Full workflows can take much longer than unit or integration tests. Extensive E2E test suites, especially for large applications, can be slow to run. This can create bottlenecks in CI/CD pipelines, slowing feedback loops and affecting development speed.
**Environment management: DevOps and QA teams might struggle to maintain stable and accurately representative staging environments. Ensuring consistent, realistic, and isolated test data across different system parts is essential. Challenges include data synchronization, privacy concerns (such as ensuring compliance with the General Data Protection Regulation [GDPR] for sensitive data), and managing large volumes of data for thorough testing.
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