testing: the more you do it, the more you'll like it
TRANSCRIPT
Testen: Je mehr Du es tust,desto mehr wirst Du es lieben
“I can’t believe we’re still talking about this!”
Testen: Je mehr Du es liebst,desto mehr wirst Du es tun
“I can’t believe we’re still talking about this!”
Sebastian Bergmann
@s_bergmann
27 years programming experience
19 years PHP experience
Co-Founder of thePHP.cc
Jeffrey A. "jam" McGuire
Evangelist, DevRel Acquia
dev.acquia.com/podcast
@horncologne
Acquia Podcast: dev.acquia.com/podcast
Introduction
Why testing? What’s the problem?
Benefits of testing.
Addressing roadblocks and objections to testing.
Result!
Outline
Why testing?
“The software team not only has to ensure that it makes a positive contribution to the business goals; it must also ensure that it makes as few negative contributions … as possible.” - Andresen.
Benefits of testing(business cases)
“Testing solves many problems, the least of which is being sure the code does what it is supposed to do.”
Benefits of testing(business cases)
“Testing solves many problems, the least of which is being sure the code does what it is supposed to do.”
The Phoenix Project: A Novel About IT, DevOps, and Helping Your Business Win
Gene Kim, Kevin Behr, George Spafford
https://en.wikipedia.org/wiki/The_Phoenix_Project_(novel)
The Four Types of Work
1. Business project
2. IT (Infrastructure/Internal) project
3. Changes (Operational/Maintenance)
4. Unplanned work
TDD & the Four Types of Work
TDD helps focus on delivering features/value through business and IT projects.
TDD makes changes (Operational/Maintenance) faster, more secure
TDD reduces unplanned work
Really?
Yes, really.
Time out!State-of-play?
Do you even test?
I find your lack of tests disturbing.
Really?
Yes, really.
http://dl.acm.org/citation.cfm?id=952753 SAC '03 Proceedings of the 2003 ACM symposium on Applied computing Pages 1135-1139 ACM New York, NY, USA ©2003 ISBN:1-58113-624-2
1
http://dl.acm.org/citation.cfm?id=1159787 ISESE '06 Proceedings of the 2006 ACM/IEEE international symposium on Empirical software engineering, Pages 356-363 ACM New York, NY, USA ©2006 ISBN:1-59593-218-6
2
http://dl.acm.org/citation.cfm?id=1070834 IEEE Transactions on Software Engineering Volume 31 Issue 3, March 2005 Page 226-237
3
http://dl.acm.org/citation.cfm?id=1802420 ISSRE'09 Proceedings of the 20th IEEE international conference on software reliability engineering, Pages 81-89 IEEE Press Piscataway, NJ, USA ©2009 ISBN: 978-1-4244-5375-7
4
http://dl.acm.org/citation.cfm?id=776892 ICSE '03 Proceedings of the 25th International Conference on Software Engineering, Pages 564-569, IEEE Computer Society Washington, DC, USA ©2003 ISBN:0-7695-1877-X
5
Pro1. 18% more functional tests passed2. More than 2X increase in code quality,
tests served as “auto documentation”3. more tests == more productivity
more productivity == better quality4. 20.9% decrease in defects,
decrease in defects found by customers
5. 50% reduction in defect rate,the test suite “will improve quality over lifetime of the software system”, “quality contract” between team members
6. TDD ROI … Show me the money!
Con1. 16% more development time2. 15% more development time
3. -
4. 30% more development time non-iterative testing (improvement possible)
5. (“minimal development productivity impact”)
6. -
Summary
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.7.4232 About the Return on Investment of Test-Driven Development (2003) Matthias M. Müller , Frank Padberg International Workshop on Economics-Driven Software Engineering Research EDSER-5
6
Conventional
TDD
Development Quality Assurance
Development
InvestmentLife Cycle Benefit
Net Return
Müller / Radberg - TDD Benefit/Cost Ratio Calculation
Photo by CEphoto, Uwe Aranas
“In most cases, a client will not state how long a comparable previous system functioned … Request this information and use it in relation to test-driven development.” - Andresen.
Photo by CEphoto, Uwe Aranas
Developers!
This book is your friend!
https://leanpub.com/SellingTestDrivenProjects
Boehm - Relative cost of a bug-fix
0
40
80
120
160 150X
50X
20X10X5X1X
Requirements Design Code Developer Tests
Acceptance Tests
Operations
Developers!
This book is your friend!
https://leanpub.com/SellingTestDrivenProjects
Delivering the project is only the beginning of delivering value.
“Many software teams present quality assurance as a separate item in their offer … This gives clients the impression that it is an element that can be eliminated.” - Andresen.
Sounds convincing … Devs?
Roadblocks,Questions, Objections
Getting to testing
Objections & Questions
1. What can developers get out testing?
2. How does testing save time and frustration?
3. But I’m writing the software twice! That’s twice as much work!
4. What’s the most important tip you can give about testing?
Objections & Questions
1. What can developers get out testing?
2. How does testing save time and frustration?
3. But I’m writing the software twice! That’s twice as much work!
4. What’s the most important tip you can give about testing?
Specification
Documentation
Verification
“Die Hauptaufgabe eines Entwicklers ist nicht das Schreiben von Code,
sondern das Verstehen eines Problems. Das Formulieren von Tests,
also der Zielvorgaben, hilft, ein Problem Schritt für Schritt zu
durchdringen. Die Tests treiben die Entwicklung also nicht als
Selbstzweck, sondern tun dies, indem sie die notwendigen Denkprozesse
anstoßen.”https://thephp.cc/neuigkeiten/2017/02/testen-haelt-mich-von-der-arbeit-ab
Carola Lilienthalllsa.de
Carola Lilienthal
class AuctionTest extends PHPUnit\Framework\TestCase{ private $auction;
protected function setUp() { $this->auction = new Auction( new User( new Name('Tess Tester'), new Email('[email protected]') ), new Description('...'), new DateTimeImmutable('2017-04-07'), new DateTimeImmutable('2017-04-15'), EUR::fromCents(100) ); }
// ...}
class AuctionTest extends PHPUnit\Framework\TestCase{ // ...
public function testUserCannotBidOnOwnAuction() { $this->expectException( CannotBidOnOwnAuctionException::class );
$this->auction->bid( new Bid( new DateTimeImmutable(‘2017-04-08'), $this->auction->getUser(), EUR::fromCents(100) ) ); }}
$ phpunit --testdox AuctionTestPHPUnit 6.0.13 by Sebastian Bergmann and contributors.
Runtime: PHP 7.1.2 with Xdebug 2.5.1Configuration: /home/sb/example/phpunit.xml
Auction [x] Has description [x] Has start date [x] Has end date [x] Has initial price [x] User can bid on auction created by another user [x] User cannot bid on own auction [x] User cannot bid on auction that has not yet started [x] User cannot bid on auction that has already ended
Result! Result!
Introduction
Why testing? What’s the problem?
Benefits of testing.
Addressing roadblocks and objections to testing.
Result!
Recap
Photo Creditshttps://creativecommons.org/licenses/by-nc-sa/2.0/:
Sebastian Bergmann https://www.flickr.com/photos/stuartherbert/6231499431
Locomotive spec https://www.flickr.com/photos/12567713@N00/281324130
Steam engine https://www.flickr.com/photos/lofink/445470024
Train maintenance https://www.flickr.com/photos/kheelcenter/5279863818/
Motorcycle rider https://www.flickr.com/photos/conner395/8339912312
https://creativecommons.org/licenses/by-nc-sa/2.0/:
Köln/Bonn Flughafen night https://www.flickr.com/photos/top10-flickr/8676295874/
Köln/Bonn Flughafen day https://www.flickr.com/photos/dirkvorderstrasse/10583451894/
Flughafen Köln/Bonn ceiling https://www.flickr.com/photos/fridgemonkey/4262843982/
—————
Köln Musical Dome photo by CEphoto, Uwe Aranas https://commons.wikimedia.org/wiki/File:Cologne_Germany_Musical-Dome-01.jpg
Developers!
This book is your friend!
https://leanpub.com/SellingTestDrivenProjects
Carola Lilienthalllsa.de
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.7.4232 About the Return on Investment of Test-Driven Development (2003) Matthias M. Müller , Frank Padberg International Workshop on Economics-Driven Software Engineering Research EDSER-5
6
Thank you!Questions?Sebastian Bergmann @[email protected]
Jeffrey A. "jam" McGuire @[email protected]@gmail.com