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Why can't you rely on 100% test coverage when using unit tests?
sobes.tech AI
Answer from AI
- Code complexity: not all code is easily testable in isolation (e.g., interactions with external systems, databases).
- Need for mocking/stubs: to isolate units, stubs are required, which also need maintenance and may inaccurately simulate the behavior of real dependencies.
- Boundary conditions and combinations: the number of possible input data and their combinations can be infinite or too large for complete coverage.
- Non-functional requirements: unit tests do not verify performance, usability, security, and other non-functional aspects.
- Integration errors: unit tests check components separately but do not guarantee their correct operation together.
- Understanding requirements deficiencies: tests are written based on understanding requirements, and errors in understanding can lead to incomplete coverage of real usage scenarios.
- Cost and time: achieving 100% coverage may be impractical in terms of time and resources for only a slight increase in quality.