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Baby Steps TDD Approaches

The document outlines a presentation on Test-Driven Development (TDD) techniques shared at a Softwerkskammer meetup in Munich, focusing on 'baby steps' approaches. It discusses methodologies such as the 'diamond kata' and emphasizes the importance of incremental changes, fast feedback, and the concept of coding with constraints. Key topics include the process of testing, implementing, and refactoring in TDD, alongside practical examples and visual retrospectives.

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Baby Steps TDD Approaches Softwerkskammer Meetup Munich @codecentric 09.04.2015 David Völkel
Agenda ● Pizza ● Theory ● Coding Kata ● Another beer
Baby Steps ● Who knows the notion?
● 2011 Kent Beck‘s Responsive Design ● 2013 Adi Bolboaca Taking Baby Steps ● 2014 Seb Rose & … Diamond Kata ● [2014 Mikado Method] How I stumbled upon…
Leap change 1 Initial code state change 2 state 1 state 2 … change n target code state ● slow feedback ● high risk ● exponential complexity ● problems hard to find
Stepping Stone change 1 Initial state change 2 state 1 state 2 … change n target state get green asap ● commit on green ● revert to green +
Stepping Stone change 1 Initial state change 2 state 1 state 2 … change n target state + fast feedback + less risk - a bit more effort
"Taking Baby Steps“ Kata Contraints (Adi Bolboaca, Erik Talboom) ● Write Feature ● Test ● Implement ● Refactoring 2 min. 2 min. red? green? git reset --hard git commit
The “Diamond Kata“ A => A B => _A_ B_B _A_ C => __A__ _B_B_ C___C _B_B_ __A__
Parallel ● Old and new version parallel at the same time ● Switch one usage at a time old create new delete old old not used anymore
My too big Feature Simplification baby feature Layer 1 Layer 2 integrated test against vertical slice
My too big Feature Simplification baby feature Layer 1 Layer 2 Narrow focus of test C => __A__ _B_B_ C___C _B_B_ __A__ C => __A__
Outside-In TDD Feature Layer 1 Layer 2 Unit test Mocks
Component Feature Layer 1 Component Helper Class vs. Method? Unit test bottom up / inside-out
On-Site TDD • Temporary assertions in production code • Delete afterwards • Even quicker: a REPL public String diamond(String s) { if (s.equals("A")) { return s; } else { assertEquals("A", predecessor(s)); return (predecessor(s) + s); } }
Test-Recycling • Start with simple test • Subsequent rewrites of the same tests B => AB B => ABB B => AnBBn
Let‘s code the “Diamond Kata“! Contraints "Taking Baby Steps“ ● Write Feature ● Test ● Implement ● Refactoring ● [Don‘t talk] A => A B => _A_ B_B _A_ C => __A__ _B_B_ C___C _B_B_ __A__ 2 min. 2 min. red? green? git reset --hard git commit
Retrospective
Images THOR https://commons.wikimedia.org/wiki/File:Parkour_leap_of_faith.j pg?uselang=de Seattle Municipal Archives https://commons.wikimedia.org/wiki/File:Kids_at_Kubota_Garde n_2003.jpg
License Creative Commons Attribution-ShareAlike 3.0 https://creativecommons.org/licenses/by-sa/3.0/de/