The Road To Test-Driven Development By Christopher Paulicka Software Engineering Manager Copyright Oversee.net 2008 11/7/2018

Introduction Not just what Test-Driven Development is… But also how to get to Test-Driven Development Copyright Oversee.net 2008 11/7/2018

Agenda What is Test-Driven Development One (Abstract) Road to Test-Driven Development Your Road to Test-Driven Development My Road to Test-Driven Development Copyright Oversee.net 2008 11/7/2018

Vocabulary Test-Driven Development – TDD Extreme Programming - XP Copyright Oversee.net 2008 11/7/2018

Thanks Oversee.net for the nice space Perl Mongers for showing up! Oversee.net for the nice space Michael Lee, Director of Engineering, for “volunteering” me All the development team here at Oversee for feedback Copyright Oversee.net 2008 11/7/2018

The Three Participants Christopher Paulicka Oversee.net Perl Mongers Copyright Oversee.net 2008 11/7/2018

Christopher Paulicka Software Development – 16 years Testing – 10 years Perl – 4 years Test-Driven Development – 1 year Copyright Oversee.net 2008 11/7/2018

Oversee Development Environment Agile/Scrum Perforce Linux/Apache/MySQL/Perl, RPM Mason/Catalyst, DBI Test::More, Test::MockObject Test::Unit, Test::WWW::Selenium Module::Build, CPAN2RPM Copyright Oversee.net 2008 11/7/2018

Perl Mongers Perl aficionados Please ask questions at any time What’s your testing experience? Copyright Oversee.net 2008 11/7/2018

What is TDD TDD is old, but kind of new Test first, but still follow requirements Part of Agile/XP, but reusable anywhere Copyright Oversee.net 2008 11/7/2018

Important to Know History of TDD in Extreme Programming History of Scrum at Oversee Copyright Oversee.net 2008 11/7/2018

Software Development Methodologies Hack Waterfall Agile Copyright Oversee.net 2008 11/7/2018

Waterfall Development Requirements Design Implement Test Maintain Copyright Oversee.net 2008 11/7/2018

Waterfall Costs Rigid design High change costs Requires expert designers up front Copyright Oversee.net 2008 11/7/2018

Examples of Agile Methodologies Extreme Programming Scrum Crystal Clear Feature Driven Development Adaptive Software Development DSDM Copyright Oversee.net 2008 11/7/2018

Extreme Programming Test-Driven Development Continuous Integration Pair Programming Refactoring Copyright Oversee.net 2008 11/7/2018

Cost of Feedback Copyright Oversee.net 2008 11/7/2018

Test-Driven Development Pick a Feature Write a Test for that Feature Run all Tests and see new Test Fail Write Code for Feature Run all Tests and see all Tests Pass Refactor Repeat Copyright Oversee.net 2008 11/7/2018

A Bit More About Refactoring Refactor the Code Refactor the Tests Refactor the Documentation Refactor the Design Copyright Oversee.net 2008 11/7/2018

Who owns testing? QA Deploy Systems Development Copyright Oversee.net 2008 11/7/2018

Types of Testing Requirements Tests Integration Tests System Tests Development Tests Copyright Oversee.net 2008 11/7/2018

Types of Development Testing Unit Tests Regression Tests Copyright Oversee.net 2008 11/7/2018

One Possible Road to TDD Test to Verify Test for Regression Test for Design Test-Driven Development Copyright Oversee.net 2008 11/7/2018

Test To Verify Problem arises Write throw away test Disposable code modifications Logging Dumping, etc Simple and Fast Gone forever… Copyright Oversee.net 2008 11/7/2018

Why Do We Do That? Habit Speed Anticipation (almost done…) Copyright Oversee.net 2008 11/7/2018

Test for Regression Problem arises Write reusable test that duplicates problem Keep regression test Run regressions anytime Copyright Oversee.net 2008 11/7/2018

Good, but Good enough? Bug driven Prevents regressions Run tests anytime in development Focused late in the curve Expects test framework Copyright Oversee.net 2008 11/7/2018

Test for Design Design API Write Code Write Tests Refactor Copyright Oversee.net 2008 11/7/2018

Development Test Processes Piece-wise Test Last Lump-sum Test Last Test First aka TDD Copyright Oversee.net 2008 11/7/2018

Test-Driven Development As Beck said in XP Good Rules, lead to Good Behavior, which give Good Unit Tests Copyright Oversee.net 2008 11/7/2018

Rules Write code only when test fails Eliminate duplication afterwards Copyright Oversee.net 2008 11/7/2018

Behaviors Organic Design Writing own tests Rapid response Modular Design Copyright Oversee.net 2008 11/7/2018

Good Unit Tests Run fast Run in isolation Easy to understand Use real data Incremental step (not too large) Copyright Oversee.net 2008 11/7/2018

Your Road To TDD Why TDD Cost/Benefit Analysis How To Start Copyright Oversee.net 2008 11/7/2018

Why Test Driven Design Tests as Use Cases Tests as Documentation Tests as Design Copyright Oversee.net 2008 11/7/2018

Possible reasons to avoid TDD Tests are programmer focused May not be requirement focused Running all tests are slow Sprinting Refactoring Comparing Copyright Oversee.net 2008 11/7/2018

Cost/Benefit of TDD Industry Analysis Personal Analysis Copyright Oversee.net 2008 11/7/2018

Benefits - Industry Analysis Reduce development lead-time significantly Programmers that write tests are more productive Rarely use a debugger Easy to revert on test failure … Copyright Oversee.net 2008 11/7/2018

Benefits – Industry Analysis (cont) Programmers tests interface first, then code Shorter implementation time High Code coverage Regressions More modular code Copyright Oversee.net 2008 11/7/2018

Costs – Industry Analysis More code Though higher productivity with TDD Costly test setup UI DB Multithreaded Large legacy code bases Copyright Oversee.net 2008 11/7/2018

Metrics – Industry Analysis TDD code passed 18 - 50% more external test cases than control group code TDD code had 10 – 50% less time spent debugging code TDD had from 0 - 16% decrease in productivity (in lines of non-test code) … Copyright Oversee.net 2008 11/7/2018

Metrics – Industry Analysis (cont) TDD has 163% more asserts/module TDD 2-3x higher test coverage line and condition coverage near 100% TDD coders spent 13% less time producing solutions that were 12% larger then control (including tests!) Copyright Oversee.net 2008 11/7/2018

Subjective – Industry Analysis After the study, when asked: TDD would stick with TDD TLD would go to TDD (60%+) No tests would go to TLD Copyright Oversee.net 2008 11/7/2018

Benefits – Personal Analysis Senior/Junior Developer Interaction Senior approve tests/API Junior implements API Senior code reviews, done Tests as Use Cases Test Documentation more stable then Code Documentation Copyright Oversee.net 2008 11/7/2018

Costs – Personal Analysis More code Though happier with more feedback Costly test setup UI - WWW::Mechanize DB – Test::MockObject Multithreaded - …heh…yes. Large Legacy Codebases are painful, but TDD may be very beneficial…it’s a start! Copyright Oversee.net 2008 11/7/2018

How To Start Believe in Testing Test Framework Test Coverage Write Tests First Copyright Oversee.net 2008 11/7/2018

Believe in Testing If it's worth building, it's worth testing. If it's not worth testing, why are you wasting your time working on it? Copyright Oversee.net 2008 11/7/2018

Test Frameworks Perl has a lot… Test::Simple Test::More Test::Unit Copyright Oversee.net 2008 11/7/2018

Test Coverage Provide metrics Devel::Cover Copyright Oversee.net 2008 11/7/2018

Write Tests First Code review tests Pair program tests Always ask, “Where’s the test?” Help make tests easier Copyright Oversee.net 2008 11/7/2018

Be Aware! You are now becoming a test expert! TDD Antipatterns Don’t test just to test… Copyright Oversee.net 2008 11/7/2018

My Road To Test-Driven Development Hewlett-Packard EMSO Idealab X1 Energy Innovations Copyright Oversee.net 2008 11/7/2018

Lessons from Hewlett-Packard Tests are nowhere near perfect Tests can prove your point Believe in tests! Copyright Oversee.net 2008 11/7/2018

Tests are nowhere near perfect 500000 lines of code Hundreds of feature tests working Applications run for 3 days I knew it was broken Copyright Oversee.net 2008 11/7/2018

Tests can prove your point No one wanted to believe it The product needed to ship Wrote random component creator/messenger/destroyer Core dump in less then a millisecond Created tests from random iterations Fixed hundreds of memory leaks and contention issues Copyright Oversee.net 2008 11/7/2018

Lessons from X1 Good Test Framework Keep each other honest Copyright Oversee.net 2008 11/7/2018

Good Test Framework Test::Unit WWW::Mechanize DBI No MockObjects Copyright Oversee.net 2008 11/7/2018

Keep each other honest Test First, not test eventually Everybody Writes Tests… …but feel free to ask for help Copyright Oversee.net 2008 11/7/2018

Lessons from Energy Innovations Cost of Refactoring Beware Gold Plating It’s easy to get lazy… Copyright Oversee.net 2008 11/7/2018

Summary Learned about TDD Learned about benefits (and costs) of TDD Learned first steps towards TDD Copyright Oversee.net 2008 11/7/2018

Q&A Copyright Oversee.net 2008 11/7/2018

Bibliography I would highly recommend “The Object Primer” by Scott W. Ambler, now in it’s third edition. http://www.agiledata.org/essays/tdd.html http://en.wikipedia.org/wiki/Test-driven_development http://en.wikipedia.org/wiki/Agile_software_development http://en.wikipedia.org/wiki/Continuous_integration http://en.wikipedia.org/wiki/Refactoring … Copyright Oversee.net 2008 11/7/2018

Bibliography (cont) http://blog.james-carr.org/?p=44 http://www.ipd.uka.de/Tichy/uploads/publikationen/136/MuellerHoefer2007.pdf http://www.acm.org/src/subpages/gf_entries_06/DavidJanzen_src_gf06.pdf http://utopia.csis.pace.edu/dps/2008/mcapellan/projects/TDD/TDD_Idea_Paper_V04-03.doc … Copyright Oversee.net 2008 11/7/2018

Bibliography (cont) http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B75H1-4FC40MJ-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=fbd92b394263506930dfafb31003a916 http://aegis.sourceforge.net/ Copyright Oversee.net 2008 11/7/2018