Mocks, Stubs, and Spies, Oh My
summary
Defines five test doubles with concrete rules: use mocks to record calls and verify indirect outputs, prefer lenient over strict mocks to avoid brittle order checks; use stubs to supply indirect inputs including responder and sabotuer behaviors; use spies to wrap real implementations and inspect internal state; use fakes as in-memory replacements (fast DB substitute) for integration tests. Calls out Mockito as the mocking tool that blurs terms and warns that overusing doubles makes tests overspecified and fragile.
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chapters (15)
- 0:00Introduction to test doubles
- 1:08Test pyramid overview
- 3:35When to use test doubles
- 4:59Mocks explained
- 7:26Mocks in unit tests
- 9:09Stubs and their role
- 11:56Stubs in testing
- 13:01Spies as test doubles
- 15:29Dummies in testing
- 16:55Fakes for performance
- 20:08Terminology confusion
- 23:17Mockito’s test doubles
- 25:50Best practices for test doubles
- 27:36Overusing test doubles
- 28:39About the speaker
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