What is end-to-end testing?

End-to-end testing (E2E testing) is a method of testing the functionality of an entire system, from start to finish, to ensure that all components work correctly together. This testing simulates the system's real-world usage and is used to verify that the system meets the requirements and behaves as expected.

E2E testing typically involves testing the entire system, including any external dependencies, such as databases, APIs, or third-party services. The test cases are designed to test the system's functionality from the user's perspective, including the user interface, business logic, and the interactions between different system components.

E2E tests are usually automated and are run after all the unit tests have been passed. These tests are designed to catch any integration issues the unit tests may have missed. E2E testing is often used in web and mobile application development, but it can be applied to any system with multiple components.