End-to-End Testing
Definition
End-to-End (E2E) testing is a methodology used to test whether the flow of an application is performing as designed from start to finish. The purpose of carrying out end-to-end tests is to identify system dependencies and to ensure that data integrity is maintained between various system components and systems.
Why It Matters
E2E tests provide the highest level of confidence that the entire system is working correctly from the user's perspective. They simulate a real user scenario and test the entire application stack.
Contextual Example
An E2E test for an e-commerce site would use a browser automation tool like Cypress or Playwright to simulate a user logging in, searching for a product, adding it to their cart, and completing the checkout process. The test would verify that each step works as expected.
Common Misunderstandings
- E2E tests are the slowest and most brittle (fragile) type of test. They are at the top of the testing pyramid and should be used sparingly.
- Because they are complex, a failure in an E2E test can be difficult to debug.