How do E2E tests differ from unit tests?
The difference in short:
| Criterion | Unit tests | E2E tests |
|---|---|---|
| What they check | an individual function or component in isolation | the whole scenario, like a user |
| Speed | very fast | slow |
| Dependencies | no external services (mocks) | real APIs, database, UI |
| Goal | make sure small parts work correctly on their own | make sure the system works end-to-end without failures |
Summary: unit test → about small logic, E2E → about the real behavior of the whole application.
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