A Taste of TDD: The basics of TDD, why it is hard and how to do it better

TESTING AND TDD

John McCaffrey@ J_McCaffrey

Wednesday, October 29, 14

AGENDA• Poll: What are your current testing practices?

•What is TDD?

•Where does it fit in the Agile landscape

• TDD basics

• Pros/Cons/Controversy

•Demo/Q&A


ME

• Started Unit testing in Java

• TDD Javascript & Ruby

• Love Testing and TDD


YOU

•What are you doing already?

•What are you hoping to learn?


TDD DEFINED


TDD DEFINED

• Software Development practice

• Focus on explicit expectations from tests

• Characterized by red/green/refactor


RED/GREEN/REFACTOR


TDD BENEFITS• Correct behavior

• Rapid feedback

• Simpler, easier to understand

• Fully covered by tests

• Living documentation

• Confidence


TDD == GTD?

• Collect

• Process

• Organize

• Review

• Do it


• not just testing in general

•more of a design practice with test benefits

• TDD is not a silver-bullet!


WHAT WE WILL COVER• Where Testing and TDD fit in Agile

• General Agile Testing practices

• TDD Practice

• Pros/Cons/Controversy

• Demo/Q&A


TDD RESOURCES

• Blogs, Books, Workshops

• Confreaks.com

• pluralsight.com


WHY IS TESTING SO CRITICAL?


DOES OUR CODE...

• function correctly?

• handle expected edge cases and exceptions?

• allow for new features and change?

•make sense to new team members?


MO’ PROBLEMS• Code changes create new bugs

• Fear of changing anything leads to worse code

• Estimates are higher, changes take longer

• Bugs, Bugs, Bugs, regression, Bugs, Bugs

• Time between build to feedback is too long


WITH TESTS

• Code change is safer

• Component design is clearer

• Feedback is quicker

• Safety and freedom to make the code better


TESTS ARE FOR EVERYONE

•Managers and Business team

•QA Team

• Support

• dev ops

• Customers


TESTING TYPES

• Unit

• Functional

• Integration/system testing

• User acceptance

•Manual testing


DIFFERENT TYPES OF TESTS


TDD APPLIED

• You can use TDD and Test-First with all types of testing

• TDD helps you focus on your specific task

• TDD may be challenging for some types of testing


TESTING & TDD IN THE

AGILE LANDSCAPE


FEEDBACK IS KEY


AGILE:FEEDBACK AT EVERY LEVEL


SHORTEST CYCLE


XP PRACTICES

• Planning Game

• On-site Customer

• Small Releases

• Simple design

• Customer Testing

• Metaphor

• Sustainable pace (40hr)

• Common Standards

• Collective Ownership

• Unit Testing

• Refactoring

• Continuous Integration

• Pair Programming


XP PRACTICES

• Planning Game

• On-site Customer

• Small Releases

• Simple design

• Customer Testing

• Metaphor

• Sustainable pace (40hr)

• Common Standards

• Collective Ownership

• Unit Testing

• Refactoring

• Continuous Integration

• Pair Programming


TDD FEEDBACK CYCLE• Code is correct

•Design is workable

• Intention is clear

•Dependencies and collaborators are minimal

• It does what the Developer intended....


IF YOU ONLY GET ONE THING OUT OF THIS...


FEEDBACK IS KEY


•Define acceptance test criteria as team, as part of the story definition

• write out the test steps

• plan to automate them

• update with any test cases that are discovered

IF YOU ONLY GET ONE THING OUT OF THIS...


TDD WON’T FIX BAD REQUIREMENTS!!


THE PAYOFF


THE AWESOME

• high coverage

• fast

• informative

• not brittle

• visible to the team


TDD IN PRACTICE


TERMINOLOGY• Unit tests

• Setup/Fixture

• Assertion

• Coverage

•Design

• Interface/contract

•Mock/Stub

•DRY

• YAGNI

• Automated tests

• Continuous integration

• Continuous deployment


TDD WORKFLOW

• write the test, watch it fail

• write “just enough” code to make it pass

• rinse/repeat, improving the tests and code as you go


SIMPLE DESIGN

• Passes all the tests

•Minimal Duplication

•Maximizes clarity

• Fewest number of classes or methods


SIMPLE DESIGN

• Low Coupling

• High Cohesion

• High Encapsulation

• SOLID


TDD WORKFLOW

•New code

• Legacy

• Bugs


NEW CODE


STORY SAMPLE

• As a Standard User I need to see my list of outstanding orders, so I can review and complete them in priority order


STORY SAMPLE

• As a Standard User I need to see my list of outstanding orders, so I can review and complete them in priority order


STORY SAMPLE

• As a Customer I need to calculate the tip for my bill, so I can save time and include a reasonable amount


CODETEST


TEST


CODE


LEGACY

• first, do no harm

• get sufficient coverage in place

• confirm existing functionality is correct

• review tests cases with team


TEST FIRST,REFACTOR LATER

I’M SERIOUS!!


CODE SAMPLE


BUGS

• write a test to confirm the bug

• change the code to fix the bug

• the test should confirm the fix


PROS/CONS


PROS• Focus

• Confidence

• Rapid Feedback

• Clear intention

• Executable documentation


CONS• TDD is HARD!!

• Refactoring is an uncertain art

• Some parts are hard to test first

• False sense of security

• Focus more on the tests than the system!


ANTI-PATT3RNS• huge setup, reused unnecessarily

• too much going on in one test

• only testing happy-path, not exceptions

• too much boiler-plate, basic tests

• over-mocking: “tests pass, but production is broken”

• not doing the ‘refactor’ part of Red/Green/Refactor


CONTROVERSY


http://david.heinemeierhansson.com/2014/tdd-is-dead-long-live-testing.html



• Used to love and promote TDD

•Dogmatic TDD is not helpful

• Focusing exclusively on speed and low-coupling

• Shaming others for not following “TDD or Die!”

CONTROVERSY


SUMMARY

• Tests are worth the investment

• Everyone on the team should care about them

• TDD is a great way to improve your code and tests

• Find an approach that works best for your team


RESOURCES• TDD is Dead - David Heinemeier-Hansson

• R.I.P. TDD - Kent Beck

• TDD “straw-men and rhetoric” - Gary Bernhardt

• Failures of “Intro to TDD” - Justin Searls

• Pragmatics of TDD - ‘Uncle’ Bob Martin

• When to Mock - ‘Uncle’ Bob Martin

• TDD Failed to become mainstream

• TDD a Love-Story - Nell Shamrell




https://www.facebook.com/notes/kent-beck/rip-tdd/750840194948847

https://www.facebook.com/notes/kent-beck/rip-tdd/750840194948847

https://www.destroyallsoftware.com/blog/2014/tdd-straw-men-and-rhetoric

https://www.destroyallsoftware.com/blog/2014/tdd-straw-men-and-rhetoric

http://blog.testdouble.com/posts/2014-01-25-the-failures-of-intro-to-tdd.html

http://blog.testdouble.com/posts/2014-01-25-the-failures-of-intro-to-tdd.html

http://blog.8thlight.com/uncle-bob/2013/03/06/ThePragmaticsOfTDD.html

http://blog.8thlight.com/uncle-bob/2013/03/06/ThePragmaticsOfTDD.html

http://blog.8thlight.com/uncle-bob/2014/05/10/WhenToMock.html

http://blog.8thlight.com/uncle-bob/2014/05/10/WhenToMock.html

http://www.phpclasses.org/blog/post/237-7-Reasons-Why-TDD-Failed-to-become-Mainstream.html

http://www.phpclasses.org/blog/post/237-7-Reasons-Why-TDD-Failed-to-become-Mainstream.html

https://www.youtube.com/watch?v=nBtO1UOK9Hs

https://www.youtube.com/watch?v=nBtO1UOK9Hs

LET’S HAVE SOMEQUESTIONS!

John McCaffrey@ J_McCaffrey


A Taste of TDD: The basics of TDD, why it is hard and how to do it better

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