End-to-end testing
Also called: E2E testing, system integration testing, integration testing
End-to-end testing follows a journey through every system it touches, from the user’s first action to the final effect in the back office or a partner system.
End-to-end testing checks the joins. A booking made in the app has to appear in the back office, raise the right invoice and reach the partner system. Each component can pass its own tests while the journey fails at a handoff.
Before testing I map the journey across the estate: which systems it crosses, who owns each, which environment each one runs in and what is stubbed. Defects found at a handoff need to reach the right team, and the map is how they get there.
End-to-end checks are slow and costly, so I keep them for the journeys where a failure costs money, identity or something that cannot be undone.