Mocks and Stubs and Spies, oh my!

Introduction to test doubles. What they are, how they're different, and where they're used.

Transcript

1. Mocks and Stubs and Spies, Oh My! Brian Gardner bit.ly/mocks-stubs-spies
2. Test Double Hierarchy Test Doubles Mock Fake Spy Stub Dummy
3. When to use Test Doubles? • System under test has indirect inputs • System under test has indirect outputs • Slow tests*
4. Types of Tests Functional Unit Integration
5. Mocking Library
6. Mocks
7. What is a mock? • Configured with expected method calls and parameters • Verifies method calls itself • Can return values for method calls (secondary)
8. Mock Types Mocks Strict Lenient
9. Where should you use it? Functional Unit Integration
10. Where should you use it? Functional Unit Integration
11. Where should you use it? Functional Unit Integration
12. Where should you use it? Functional Unit Integration
13. Mockito mocks
14. Stubs
15. What is a Stub? • Returns values you specify in test • Can not return anything not specified • Does not record number of interactions
16. Stub Types Stubs Responder Saboteur Temporary
17. where should you use it? Functional Unit Integration
18. where should you use it? Functional Unit Integration
19. where should you use it? Functional Unit Integration
20. where should you use it? Functional Unit Integration
21. Mockito Stubs
22. Spies
23. What is a Spy? • Mock + Stub • Returns values based on test configuration • Records method calls or other information • Allows you to verify method calls and parameters
24. where should you use it? Functional Unit Integration
25. where should you use it? Functional Unit Integration
26. where should you use it? Functional Unit Integration
27. where should you use it? Functional Unit Integration
28. Mockito Spies
29. Other Mockito Spies
30. Dummies
31. What is a Dummy? • Never actually used in a test • Just fills the parameter list
32. Where should you use it? Functional Unit Integration
33. Where should you use it? Functional Unit Integration
34. Where should you use it? Functional Unit Integration
35. Where should you use it? Functional Unit Integration
36. Mockito dummies
37. Fakes
38. What is a Fake? • Real object specifically for test • Replaces an object in test with a simpler/faster implementation
39. where should you use it? Functional Unit Integration
40. where should you use it? Functional Unit Integration
41. where should you use it? Functional Unit Integration
42. where should you use it? Functional Unit Integration
43. Mockito Fakes N/A
44. Recap • Use correct terms for more effective communication • Match test doubles to the appropriate tests • Don’t over use them
45. Issues
46. Who am I? Brian Gardner @BrianGardnerAtl bit.ly/mocks-stubs-spies
47. Questions?