Adopt-a-pytest

pytest is a testing framework that makes writing and running Python tests simpler. Adopting new tooling in a large system is often a burden. How can you introduce pytest gradually with minimal pain?

With its simplified syntax, powerful fixture behaviors, detailed test reports, and plugin-based architecture, pytest has a lot to offer. Whether you're new to Python unit testing or you've been using unittest for a while, pytest may be something to consider. It's not too hard to get up and running with pytest on a fresh project, but how can you retrofit an existing project without having to refactor the world all at once?

Transcript

1. @easyaspython PyOo !1
2. @easyaspython Adopt-a-pytest PyOhio 2019 Dane Hillard Lead Web Application Developer !2
3. @easyaspython About me Reasons to pytest How to pytest More reasons to pytest !3
4. @easyaspython What’s a Dane? !4
5. @easyaspython ! Developing in Python (and Django) for ~7 years ! Web app development for ~4 years ! I do hobbies ◦ Lifestyle photographer ◦ Musician ◦ Epicurean ◦ Competitive ballroom dancer ◦ Blogger ◦ Author !5
6. @easyaspython Practices of the Python Pro ! bit.ly/the-python-pro ! Gentle intro to software design practices !6
7. @easyaspython !7
8. @easyaspython !8
9. @easyaspython !9 ! 50+ apps ! 900+ modules ! 300+ test modules ! 2K+ tests Before: Manual, occasional, often broken Now: Automated*, every commit, not broken
10. @easyaspython What’s a pytest? !10
11. @easyaspython Simpler syntax !11
12. @easyaspython !12
13. @easyaspython !13
14. @easyaspython !14
15. @easyaspython !15
16. @easyaspython Fixtures !16
17. @easyaspython !17
18. @easyaspython !18
19. @easyaspython !19
20. @easyaspython !20
21. @easyaspython Marks, patterns, filtering !21
22. @easyaspython !22
23. @easyaspython !23
24. @easyaspython !24
25. @easyaspython !25
26. @easyaspython Durations !26
27. @easyaspython !27
28. @easyaspython Parallels for most unittest stuff !28
29. @easyaspython !29
30. @easyaspython pytest is lovely !30
31. @easyaspython Retrofitting is hard !31
32. @easyaspython Step 0: Create a baseline !32
33. @easyaspython !33
34. @easyaspython Step 1: Install pytest !34
35. @easyaspython !35
36. @easyaspython Step 1a: Install pytest-cov !36
37. @easyaspython Step 2: Run pytest !37
38. @easyaspython !38
39. @easyaspython !39
40. @easyaspython !40
41. @easyaspython !41
42. @easyaspython Step 3: Fix test collection !42
43. @easyaspython Test discovery !43 Convention unittest pytest Ⓜ test*.py ✅ Ⓜ test_*.py ✅ ✅ Ⓜ *_test.py ✅ Ⓜ *_tests.py Ⓒ *(unittest.TestCase) ✅ ✅ ⓜ test_* ✅ ✅ Ⓒ Test* ✅ ⓜ test_* ✅ ⓕ test_* ✅
44. @easyaspython !44
45. @easyaspython !45
46. @easyaspython Option A: Rename test modules !46
47. @easyaspython Option B: pytest.ini !47
48. @easyaspython !48
49. @easyaspython !49
50. @easyaspython !50
51. @easyaspython Step 4: Shim things !51
52. @easyaspython conftest.py !52
53. @easyaspython !53
54. @easyaspython !54
55. @easyaspython Step 5: Use pytest in new tests !55
56. @easyaspython Step 6: Rewrite old tests !56
57. @easyaspython Step 7: Use helpful plugins !57
58. @easyaspython Step 8: Integrate with CI/CD !58
59. @easyaspython Incremental !59
60. @easyaspython Helpful fallbacks !60
61. @easyaspython Adopt and embrace !61
62. @easyaspython What else is a pytest? !62
63. @easyaspython Parameterization !63
64. @easyaspython !64
65. @easyaspython !65
66. @easyaspython !66
67. @easyaspython !67
68. @easyaspython !68
69. @easyaspython !69
70. @easyaspython !70
71. @easyaspython !71
72. @easyaspython !72
73. @easyaspython Works with Jenkins !73
74. @easyaspython Works with tox !74
75. @easyaspython Plugin-based architecture (pluggy) !75
76. @easyaspython pytest pytest-cov pytest-django pytest-randomly !76
77. @easyaspython !77
78. @easyaspython Thanks !78