Beyond Unit Testing: The Real Value of Test-Driven Development - Slalom

Twenty years after the public introduction of Test-Driven Development (TDD), in Kent Beck's Extreme Programming Explained, it remains a commonly misunderstood and underutilized practice. While there are many who espouse the benefits of TDD, misconceptions about the practice and its perceived learning curve serve to dampen its impact on the software industry.

This talk introduces the misconceptions about TDD, as being just another way to write unit tests. It disputes this belief by refocusing on the many benefits of the practice. The talk will detail the resulting sustainable, high-quality test suites that are a product of TDD. Additionally, it will describe the less visible benefits like software design feedback, and improvements to development structure and developer workflow; all of which are possible through the continued practice of TDD.

If you are a software engineer or a technical leader wanting to learn more about TDD, looking for the motivation to give the practice a try, or are looking for ways to encourage your team(s) to learn the practice, this talk is for you.

Transcript

1. Beyond Unit Testing Anthony Sciamanna @asciamanna anthonysciamanna.com The Real Value of Test-Driven Development October 11, 2019
2. TDD Refresher @asciamanna anthonysciamanna.com
3. TDD Refresher @asciamanna anthonysciamanna.com
4. Let’s go back in time! @asciamanna anthonysciamanna.com
5. Discovered at Hunter Industries in 2011 by a team coached by Woody Zuill 1994 A Very Brief History of TDD Discovered at Hunter Industries in 2011 by a team coached by Woody Zuill Kent Beck releases the first version of the SUnit framework for Smalltalk @asciamanna anthonysciamanna.com
6. Discovered at Hunter Industries in 2011 by a team coached by Woody Zuill 1994 A Very Brief History of TDD Discovered at Hunter Industries in 2011 by a team coached by Woody Zuill Kent Beck releases the first version of the SUnit framework for Smalltalk 1995 @asciamanna Kent demos TDD to Ward Cunningham at OOPSLA Austin in October. Details of the C3 Project start being publicized anthonysciamanna.com
7. Discovered at Hunter Industries in 2011 by a team coached by Woody Zuill 1994 A Very Brief History of TDD Discovered at Hunter Industries in 2011 by a team coached by Woody Zuill Kent Beck releases the first version of the SUnit framework for Smalltalk 1995 @asciamanna Kent releases Extreme Programming Explained 1999 Kent demos TDD to Ward Cunningham at OOPSLA Austin in October. Details of the C3 Project start being publicized anthonysciamanna.com
8. TDD Is a Testing Practice @asciamanna anthonysciamanna.com
9. I don’t care if people write tests first or last. As long as they get written. @asciamanna “ ” - Anonymous Tech Lead anthonysciamanna.com
10. @asciamanna Ignores Design and Workflow Benefits of TDD anthonysciamanna.com
11. @asciamanna Benefits of TDD anthonysciamanna.com
12. @asciamanna Benefits of TDD Test Suite Externally Visible Artifacts anthonysciamanna.com
13. @asciamanna Benefits of TDD Test Suite Externally Visible Artifacts anthonysciamanna.com
14. @asciamanna Benefits of TDD Test Suite Externally Visible Artifacts Software Design anthonysciamanna.com
15. @asciamanna Benefits of TDD Test Suite Externally Visible Artifacts Software Design Developer Workflow anthonysciamanna.com
16. @asciamanna Benefits of TDD Test Suite Software Design Developer Workflow Externally Visible Artifacts anthonysciamanna.com
17. @asciamanna TDD Triple Balance Made Making Maker anthonysciamanna.com
18. @asciamanna Benefits of TDD Test Suite Software Design Developer Workflow Externally Visible Artifacts anthonysciamanna.com
19. Test Suite Benefits Why we prefer TDD-style tests over Test After Tests
20. Test Suite Quality Production Code Quality @asciamanna Disclaimer #1 Test suite quality influences production code quality and vice-versa anthonysciamanna.com
21. You Can’t Write Good Tests for Bad Code • Wrapping non-testable code in unit tests results in brittle, low-quality tests • Test-first practices enable writing high quality production code and high-quality tests @asciamanna anthonysciamanna.com
22. @asciamanna The TDD Quality Cycle anthonysciamanna.com Test Suite Production Code 2. Code under test must be testable (loosely coupled) Refactoring Refactoring 3. Enables tests to be small, precise, fast, isolated and independent Virtuous Cycle 1. Tests are written first
23. Microtest A short, simple, fast, isolated*, test that probes the behavior of a single class @asciamanna *Isolated does not mean we have to mock every dependency anthonysciamanna.com
24. Microtests Don’t Access a network Access a database Access the filesystem Depend on other tests Require a complex environment to run in @asciamanna anthonysciamanna.com
25. S O S @asciamanna anthonysciamanna.com
26. Small O S @asciamanna anthonysciamanna.com
27. Small Obvious S @asciamanna anthonysciamanna.com
28. Small Obvious Simple @asciamanna anthonysciamanna.com
29. Small @asciamanna ~12 LOC or less per test anthonysciamanna.com
30. @asciamanna Obvious anthonysciamanna.com
31. Arrange Act Assert Arrange – Act – Assert @asciamanna Or Given - When - Then anthonysciamanna.com
32. Standardize common test constructs Create the object under test in Setup Standard name result to be asserted Standard name for object under test @asciamanna anthonysciamanna.com
33. Simple @asciamanna Avoid branching and flow control logic in tests anthonysciamanna.com
34. How To Stop Hating Your Test Suite Logic in tests confuses the story of what’s being tested. Test- scoped logic is hard to read and errors are easy to miss. - Justin Searls, Co-founder Test Double @asciamanna anthonysciamanna.com
35. How To Stop Hating Your Test Suite Test code is untested code! - Justin Searls, Co-founder Test Double @asciamanna anthonysciamanna.com
36. @asciamanna Test After Test First Manual testing often takes precedence Unit testing at end tends to be skipped to hit deadlines All code is tested as it is created or modified Feels like busy work if code is manually tested and considered “done” The test is the path to changing the system Code is not influenced by tests to be testable Code is influenced by the tests to be testable Tests don’t serve as feedback loops Tests are continuous feedback loops, supports refactoring and software design Tests don’t get refactored – created at end Tests are continuously refactored Tests are less comprehensive when added at end Tests are more comprehensive when added with each code change Coverage as a build gate often required (commonly 70% coverage) Coverage metrics unnecessary anthonysciamanna.com
37. Software Design Benefits Tests guiding quality software design
38. Disclaimer #2 @asciamanna TDD influences design quality anthonysciamanna.com But it’s not a silver bullet
39. @asciamanna Disclaimer #2 TDD alone influences design quality anthonysciamanna.com High Cohesion Loose Coupling Small Classes Small Methods
40. @asciamanna Disclaimer #2 TDD provides a mechanism for learning software design anthonysciamanna.com High Cohesion Loose Coupling Small Classes Small Methods
41. @asciamanna Practitioners still need to understand the concepts of software design Disclaimer #2 High Cohesion Loose Coupling Code Smells Design Patterns SOLID Refactoring Encapsulation GRASP Connascence anthonysciamanna.com
42. @asciamanna Microtests are litmus tests for software design quality anthonysciamanna.com
43. Examples @asciamanna anthonysciamanna.com
44. Too Much Test Setup Too Many Dependencies Too Many Arguments Arguments are Too Complex Code Under Test Doing Too Much @asciamanna anthonysciamanna.com
45. Multiple ‘Act’ Steps Temporal Coupling Exists Complicated API Client needs to know too much about object under test @asciamanna Too Many Steps to Invoke Method Under Test anthonysciamanna.com
46. Too Many Asserts Returning too complex of a type Method under test doing too much @asciamanna anthonysciamanna.com
47. Too Many Test Cases Too much branching logic Method under test is doing too much @asciamanna anthonysciamanna.com
48. Client-First Design TDD enables software design from a client’s perspective. Leads to better designed interfaces between objects @asciamanna anthonysciamanna.com
49. Refactoring into design yields a better design than Big Design Up Front Requirements Design Code Test Waterfall Mindset Requirements Test Code Design (Refactor) (Test-Driven) Agile Mindset Slide courtesy of Mike Rieser (@MichaelRieser) @asciamanna anthonysciamanna.com
50. Developer Workflow Benefits Short, fast feedback cycles improve productivity
51. Nearly instantaneous feedback loops @asciamanna anthonysciamanna.com
52. Fast Feedback Loops key to developer productivity & high performing teams @asciamanna anthonysciamanna.com
53. @asciamanna anthonysciamanna.com
54. Resilient to Interruptions @asciamanna anthonysciamanna.com
55. TDD-created Microtests are save states for system functionality @asciamanna anthonysciamanna.com
56. @asciamanna anthonysciamanna.com
57. @asciamanna anthonysciamanna.com BIG PROBLEM
58. @asciamanna anthonysciamanna.com BIG PROBLEM Great software is created by GREAT TEAMS not heroic, rockstar, 10X developers working in isolation
59. @asciamanna anthonysciamanna.com BIG PROBLEM Software development is a communication game Communication is the professional developer’s first order of business. Perhaps you thought that ‘getting it working’ was the first order of business for a professional developer. I hope by now, however, this book has disabused you of that idea. - Robert Martin, Clean Code
60. System is always in a working state @asciamanna anthonysciamanna.com
61. Tiny Validations @asciamanna anthonysciamanna.com
62. @asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/
63. @asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/
64. @asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/
65. @asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/
66. Mental Benefits of TDD One of the hardest things to communicate about Test-Driven Development is the mental state it puts you in…On the original C3 project…progress was steady and unhurried; because it was unhurried it seemed slow, but looking back on how much we got done, it was clear that despite the unhurried feeling progress was really fast. “ ” Martin Fowler - Afterword - Kent Beck’s TDD By Example @asciamanna anthonysciamanna.com
67. Mental Benefits of TDD Concrete and visible progress on small incremental goals @asciamanna anthonysciamanna.com
68. Mental Benefits of TDD Achieving Profluence @asciamanna anthonysciamanna.com
69. Mental Benefits of TDD Little or no time spent in the debugger or on repetitive, time consuming manual checks @asciamanna anthonysciamanna.com
70. Learning TDD will help improve software design, developer workflow, increases developer happiness, and it’s a lot of fun! https://geepawhill.org anthonysciamanna.com https://github.com/testdouble/contributing-tests/wiki Test Double – Contributing Tests Wiki Industrial Logic eLearning https://www.industriallogic.com/elearning/ @asciamanna
71. @asciamanna http://bit.ly/slalom-beyond-unit-testing anthonysciamanna.com
72. Attributes • Pygmy Marmoset - https://www.flickr.com/photos/gopak/39889008421 • SOS - https://www.flickr.com/photos/itupictures/16654290295 • Darts - https://www.flickr.com/photos/mike-burns/374198933 • Quote - Nick Youngson CC BY-SA 3.0 • Silver Bullet - https://www.flickr.com/photos/moneymetals/34301000331 • Litmus test - https://commons.wikimedia.org/wiki/File:Blue_and_red_litmus_paper.JPG • Self-operating napkin - https://upload.wikimedia.org/wikipedia/commons/8/88/Self- operating_napkin_%28Rube_Goldberg_cartoon_with_caption%29.jpg • Glass Cockpit - https://upload.wikimedia.org/wikipedia/commons/9/9f/C-5M_Cockpit.jpg • Public Domain, https://commons.wikimedia.org/w/index.php?curid=2466026 • Stack of Papers - https://upload.wikimedia.org/wikipedia/commons/b/b6/FileStack_retouched.jpg • El Diablo - https://en.wikipedia.org/wiki/Fire_Ball#/media/File:El_Diablo_Roller_Coaster.jpg • Creative Commons license: https://creativecommons.org/licenses/by/2.0/