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

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Beyond Unit Testing Anthony Sciamanna @asciamanna anthonysciamanna.com The Real Value of Test-Driven Development October 11, 2019

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TDD Refresher @asciamanna anthonysciamanna.com

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TDD Refresher @asciamanna anthonysciamanna.com

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Let’s go back in time! @asciamanna anthonysciamanna.com

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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

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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

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TDD Is a Testing Practice @asciamanna anthonysciamanna.com

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I don’t care if people write tests first or last. As long as they get written. @asciamanna “ ” - Anonymous Tech Lead anthonysciamanna.com

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@asciamanna Ignores Design and Workflow Benefits of TDD anthonysciamanna.com

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@asciamanna Benefits of TDD anthonysciamanna.com

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@asciamanna Benefits of TDD Test Suite Externally Visible Artifacts anthonysciamanna.com

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@asciamanna Benefits of TDD Test Suite Externally Visible Artifacts anthonysciamanna.com

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@asciamanna Benefits of TDD Test Suite Externally Visible Artifacts Software Design anthonysciamanna.com

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@asciamanna Benefits of TDD Test Suite Externally Visible Artifacts Software Design Developer Workflow anthonysciamanna.com

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@asciamanna Benefits of TDD Test Suite Software Design Developer Workflow Externally Visible Artifacts anthonysciamanna.com

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@asciamanna TDD Triple Balance Made Making Maker anthonysciamanna.com

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@asciamanna Benefits of TDD Test Suite Software Design Developer Workflow Externally Visible Artifacts anthonysciamanna.com

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Test Suite Benefits Why we prefer TDD-style tests over Test After Tests

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Test Suite Quality Production Code Quality @asciamanna Disclaimer #1 Test suite quality influences production code quality and vice-versa anthonysciamanna.com

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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

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@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

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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

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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

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S O S @asciamanna anthonysciamanna.com

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Small O S @asciamanna anthonysciamanna.com

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Small Obvious S @asciamanna anthonysciamanna.com

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Small Obvious Simple @asciamanna anthonysciamanna.com

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Small @asciamanna ~12 LOC or less per test anthonysciamanna.com

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@asciamanna Obvious anthonysciamanna.com

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Arrange Act Assert Arrange – Act – Assert @asciamanna Or Given - When - Then anthonysciamanna.com

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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

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Simple @asciamanna Avoid branching and flow control logic in tests anthonysciamanna.com

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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

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How To Stop Hating Your Test Suite Test code is untested code! - Justin Searls, Co-founder Test Double @asciamanna anthonysciamanna.com

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@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

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Software Design Benefits Tests guiding quality software design

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Disclaimer #2 @asciamanna TDD influences design quality anthonysciamanna.com But it’s not a silver bullet

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@asciamanna Disclaimer #2 TDD alone influences design quality anthonysciamanna.com High Cohesion Loose Coupling Small Classes Small Methods

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@asciamanna Disclaimer #2 TDD provides a mechanism for learning software design anthonysciamanna.com High Cohesion Loose Coupling Small Classes Small Methods

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@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

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@asciamanna Microtests are litmus tests for software design quality anthonysciamanna.com

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Examples @asciamanna anthonysciamanna.com

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Too Much Test Setup Too Many Dependencies Too Many Arguments Arguments are Too Complex Code Under Test Doing Too Much @asciamanna anthonysciamanna.com

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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

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Too Many Asserts Returning too complex of a type Method under test doing too much @asciamanna anthonysciamanna.com

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Too Many Test Cases Too much branching logic Method under test is doing too much @asciamanna anthonysciamanna.com

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Client-First Design TDD enables software design from a client’s perspective. Leads to better designed interfaces between objects @asciamanna anthonysciamanna.com

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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

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Developer Workflow Benefits Short, fast feedback cycles improve productivity

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Nearly instantaneous feedback loops @asciamanna anthonysciamanna.com

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Fast Feedback Loops key to developer productivity & high performing teams @asciamanna anthonysciamanna.com

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@asciamanna anthonysciamanna.com

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Resilient to Interruptions @asciamanna anthonysciamanna.com

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TDD-created Microtests are save states for system functionality @asciamanna anthonysciamanna.com

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@asciamanna anthonysciamanna.com

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@asciamanna anthonysciamanna.com BIG PROBLEM

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@asciamanna anthonysciamanna.com BIG PROBLEM Great software is created by GREAT TEAMS not heroic, rockstar, 10X developers working in isolation

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@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

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System is always in a working state @asciamanna anthonysciamanna.com

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Tiny Validations @asciamanna anthonysciamanna.com

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@asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/

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@asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/

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@asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/

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@asciamanna anthonysciamanna.com GeePaw Hill – TDD & the Lump of Coding Fallacy https://www.geepawhill.org/2018/04/14/tdd-the-lump-of-coding-fallacy/

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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

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Mental Benefits of TDD Concrete and visible progress on small incremental goals @asciamanna anthonysciamanna.com

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Mental Benefits of TDD Achieving Profluence @asciamanna anthonysciamanna.com

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Mental Benefits of TDD Little or no time spent in the debugger or on repetitive, time consuming manual checks @asciamanna anthonysciamanna.com

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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

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@asciamanna http://bit.ly/slalom-beyond-unit-testing anthonysciamanna.com

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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/