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

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 November 19, 2019
2. • Passionate about Extreme Programming (XP), Lean Software Development, and Modern Agile. • Expertise in helping teams and development organizations improve how they work, the quality of their code, and their ability to deliver value to their customers. • Focusing on technical excellence, continuous improvement, and continuous learning. Anthony Sciamanna Software Engineer, Technical Agile Coach, Blogger & Organizer of the PhillyXP user group. @asciamanna anthonysciamanna.com
3. TDD Refresher @asciamanna anthonysciamanna.com Image by Industrial Logic Senior Consultant - Tim Ottinger
4. TDD Refresher @asciamanna anthonysciamanna.com
5. TDD Refresher @asciamanna anthonysciamanna.com
6. Let’s go back in time! @asciamanna 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 @asciamanna anthonysciamanna.com
8. 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 1995 @asciamanna Kent demos TDD to Ward Cunningham at OOPSLA Austin in October. Details of the C3 Project start being publicized anthonysciamanna.com Kent Beck releases the first version of the SUnit framework for Smalltalk
9. 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 1995 @asciamanna Kent demos TDD to Ward Cunningham at OOPSLA Austin in October. Details of the C3 Project start being publicized anthonysciamanna.com Kent Beck releases the first version of the SUnit framework for Smalltalk On a flight from Zurich to Atlanta (OOPSLA ‘97) Erich Gamma and Kent Beck create JUnit for Java 1997
10. 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 1995 @asciamanna Kent demos TDD to Ward Cunningham at OOPSLA Austin in October. Details of the C3 Project start being publicized anthonysciamanna.com Kent Beck releases the first version of the SUnit framework for Smalltalk On a flight from Zurich to Atlanta (OOPSLA ‘97) Erich Gamma and Kent Beck create JUnit for Java 1997 Kent releases Extreme Programming Explained 1999
11. TDD Is a Testing Practice @asciamanna anthonysciamanna.com
12. I don’t care if people write tests first or last. As long as they get written. @asciamanna “ ” - Anonymous Tech Lead anthonysciamanna.com
13. @asciamanna Ignores Design and Workflow Benefits of TDD anthonysciamanna.com
14. @asciamanna Benefits of TDD anthonysciamanna.com
15. @asciamanna Benefits of TDD Test Suite Externally Visible Artifacts anthonysciamanna.com
16. @asciamanna Benefits of TDD Test Suite Externally Visible Artifacts anthonysciamanna.com
17. @asciamanna Benefits of TDD Test Suite Externally Visible Artifacts Software Design anthonysciamanna.com
18. @asciamanna Benefits of TDD Test Suite Externally Visible Artifacts Software Design Developer Workflow anthonysciamanna.com
19. @asciamanna Benefits of TDD Test Suite Software Design Developer Workflow Externally Visible Artifacts anthonysciamanna.com
20. @asciamanna TDD Triple Balance Made Making Maker anthonysciamanna.com
21. @asciamanna Benefits of TDD Test Suite Software Design Developer Workflow Externally Visible Artifacts anthonysciamanna.com
22. Test Suite Benefits Why we prefer TDD-style tests over Test After Tests
23. Test Suite Quality Production Code Quality @asciamanna Disclaimer #1 Test suite quality influences production code quality and vice-versa anthonysciamanna.com
24. 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
25. @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
26. 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
27. 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
28. S O S @asciamanna anthonysciamanna.com
29. Small O S @asciamanna anthonysciamanna.com
30. Small Obvious S @asciamanna anthonysciamanna.com
31. Small Obvious Simple @asciamanna anthonysciamanna.com
32. Small @asciamanna ~12 LOC or less per test anthonysciamanna.com
33. @asciamanna Obvious anthonysciamanna.com
34. Arrange Act Assert Arrange – Act – Assert @asciamanna Or Given - When - Then anthonysciamanna.com
35. 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
36. Simple @asciamanna Avoid branching and flow control logic in tests anthonysciamanna.com
37. 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
38. How To Stop Hating Your Test Suite Test code is untested code! - Justin Searls, Co-founder Test Double @asciamanna anthonysciamanna.com
39. @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
40. Software Design Benefits Tests guiding quality software design
41. Disclaimer #2 @asciamanna TDD influences design quality anthonysciamanna.com But it’s not a silver bullet
42. @asciamanna Disclaimer #2 TDD alone influences design quality anthonysciamanna.com High Cohesion Loose Coupling Small Classes Small Methods
43. @asciamanna Disclaimer #2 TDD provides a mechanism for learning software design anthonysciamanna.com High Cohesion Loose Coupling Small Classes Small Methods
44. @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
45. @asciamanna Microtests are litmus tests for software design quality anthonysciamanna.com
46. Examples @asciamanna anthonysciamanna.com
47. Too Much Test Setup Too Many Dependencies Too Many Arguments Arguments are Too Complex Code Under Test Doing Too Much @asciamanna anthonysciamanna.com
48. 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
49. Too Many Asserts Returning too complex of a type Code under test doing too much @asciamanna anthonysciamanna.com
50. Too Many Test Cases Too much branching logic Code under test is doing too much @asciamanna anthonysciamanna.com
51. Client-First Design / Outside-In TDD enables software design from a client’s perspective. Leads to better designed interfaces between objects @asciamanna anthonysciamanna.com
52. 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
53. Developer Workflow Benefits Short, fast feedback cycles improve productivity
54. Nearly instantaneous feedback loops @asciamanna anthonysciamanna.com
55. Fast Feedback Loops key to developer productivity & high performing teams @asciamanna anthonysciamanna.com
56. @asciamanna anthonysciamanna.com
57. Resilient to Interruptions @asciamanna anthonysciamanna.com
58. TDD-created Microtests are save states for system functionality @asciamanna anthonysciamanna.com
59. @asciamanna anthonysciamanna.com
60. @asciamanna anthonysciamanna.com BIG PROBLEM
61. @asciamanna anthonysciamanna.com BIG PROBLEM Great software is created by GREAT TEAMS not heroic, rockstar, 10X developers working in isolation
62. @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
63. System is always in a working state @asciamanna anthonysciamanna.com
64. Tiny Validations @asciamanna anthonysciamanna.com
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. @asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/
67. @asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/
68. @asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/
69. 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
70. Mental Benefits of TDD Concrete and visible progress on small incremental goals @asciamanna anthonysciamanna.com
71. Mental Benefits of TDD Achieving Profluence @asciamanna anthonysciamanna.com
72. Mental Benefits of TDD Little or no time spent in the debugger or on repetitive, time consuming manual checks @asciamanna anthonysciamanna.com
73. 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
74. Learning TDD will help improve software design, developer workflow, increases developer happiness, and it’s a lot of fun! anthonysciamanna.com @asciamanna https://schmonz.com/2018/08/14/lean-agile-edinburgh- august-2018-programming-for-nonprogrammers/ https://pragprog.com/magazines/2011-11/testdriven-development Test-Driven Development: A Guide for Non-Programmers by Jeff Langr Lean Agile Edinburgh August 2018: Programming For Non-Programmers by Amitai Schleier
75. @asciamanna http://bit.ly/phillyxp-beyond-unit-testing anthonysciamanna.com
76. 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/