The document discusses the pros and cons of using mocks in software testing, highlighting isolation, speed, and accuracy as advantages, while mentioning issues like avoided contracts and reliance on integrations as disadvantages. It contrasts this with testing without mocks, which offers benefits like reliable refactoring but has longer runtimes and potential snowball effects. Ultimately, it suggests a nuanced approach to using mocks, recommending their use in specific scenarios like networking and system calls.

1. Some strange stories about
mocks
And why we don’t like them?

2. Andrew
Nashkolniy
Matic Insurance

3. Story #1: The Prehistory

8. Story #2: Testing with mocks

10. With Mocks Pros:
- Isolation.

11. With Mocks Pros:
- Isolation.
- Speed.

12. With Mocks Pros:
- Isolation.
- Speed.
- Accuracy.

14. With Mocks Cons:
- Avoided Contracts.

15. With Mocks Cons:
- Avoided Contracts.
- Rely on Integrations.

16. With Mocks Cons:
- Avoided Contracts.
- Rely on Integrations.
- Hard Refactoring.

17. Story #3: Testing without mocks

18. Without Mocks Pros:
- Refactoring.

19. Without Mocks Pros:
- Refactoring.
- Reliability.

20. Without Mocks Cons:
- Longer runtime.

21. Without Mocks Cons:
- Longer runtime.
- Snowball effect.

22. Without Mocks Cons:
- Longer runtime.
- Snowball effect.
- You still use mocks.

24. Story #4: Origins

25. Problems with mocks in Java:
- Other classes side effects.

26. Problems with mocks in Ruby:
- Weak input params checks.
- No output params checks.
- Other classes side effects.

27. Interfaces
&
Strong typing

28. Unacceptable problems:
- Refactoring difficulties.

29. Unacceptable problems:
- Refactoring difficulties.
- Unreliable tests.

31. No mocks by default. But...

32. Good usage mocks:
- Networking.
- Streams.
- IO operations.
- Time.
- System calls.

33. In the very end it really depends

34. Materials:
- https://www.youtube.com/watch?v=KYG5C1CEkOk
- https://medium.com/javascript-scene/mocking-is-a-code-smell-944a70
c90a6a
- https://blog.codecentric.de/en/2018/03/mock-what-when-how
- https://blog.carbonfive.com/2011/02/11/better-mocking-in-ruby
- https://www.solutionsiq.com/resource/blog-post/to-mock-or-not-to-mock-is-that-even-a-question
- https://clean-swift.com/to-mock-or-not-to-mock
- https://blog.codecentric.de/en/2017/07/mocks-real-thing-tips-better-unit-testing
- https://dev.to/asizikov/you-are-mocking-it-wrong-5gh3
- https://www.swiftbysundell.com/posts/mock-free-unit-tests-in-swift
- https://semaphoreci.com/community/tutorials/mocking-with-rspec-doubles-and-expectations
- https://tomassetti.me/mocking-in-java-why-mocking-why-not-mocking-mocking-also-those-awful-private-static-methods
- https://softwareengineering.stackexchange.com/questions/363112/is-it-really-a-bad-practice-to-mock-a-pojo-value-object-if-you-dont-care-ab
ou
- https://stackoverflow.com/questions/6875173/to-mock-or-not-to-mock
- ...

35. Thank you!