what is e2e

End-to-end testing, also known as E2E testing, is a software testing methodology that verifies the working order of a software product in a start-to-finish process. It is a way to make sure that applications behave as expected and that the flow of data is maintained for all kinds of user tasks and processes. In E2E testing, the software is tested from the end users perspective, simulating a real user scenario, including the user interface, backend services, databases, and network communication. The objective of E2E testing is to identify bugs that arise when all components are integrated, ensuring that the application delivers the expected output as a unified entity. E2E testing is usually executed after functional and system testing, and it uses actual production-like data and test environment to simulate real-time settings. Automated testing tools like Selenium, Cypress, and Appium are commonly used for E2E testing to improve efficiency and accuracy. E2E testing is necessary for applications based on SOA (service-oriented architecture) or cloud environments, and for apps to consist of multiple components that must work together for successful operation. The two types of E2E tests are horizontal and vertical. Horizontal E2E testing checks a specific layer or component works, while vertical E2E testing ensures a particular function works smoothly from the front-end interface down to the server and database.