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Introduction to test_driven_development
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Introduction to test_driven_development



This is the slides of my talk @ Taiwan Java User Group on 2011/07/09.

This is the slides of my talk @ Taiwan Java User Group on 2011/07/09.

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    Introduction to test_driven_development Introduction to test_driven_development Presentation Transcript

    • Introduction toTest-Driven Development Hao-Cheng Lee 本著作係依據創用 CC Attribution-ShareAlike 3.0 Unported 授權 條款進行授權。如欲瀏覽本授權條款之副本,請造訪 http: //creativecommons.org/licenses/by-sa/3.0/ ,或寄信至 Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA 。
    • About me● Hao-Cheng Lee● Java Engineer for 7+ years● Software Engineer @ Armorize● Interested in Java, Scala, TDD, CI● email: haocheng.lee@gmail.com● twitter: haocheng● Google+: 浩誠
    • Download Java 7 RC Now Project Coin Slides
    • Agenda● What is TDD?● Why use TDD?● How to do TDD?● Pros and Cons● How do I start?
    • TDD = TFD +Refactoring
    • Not aboutwriting tests...
    • TDD is aboutwriting better code
    • from http://ch.englishbaby.com/forum/LifeTalk/thread/441379
    • Test Myths
    • I have no time for testing
    • Technical Debt from http://www.freedebtadvice-uk.com/
    • My code isBUG-FREE!
    • from http://vincentshy.pixnet.net/blog/post/5397455
    • QA will do the testing
    • Black Box Testing from http://www.jasonser.com/marketing-black-box/
    • http://www.ocoee.org/Departments/HR/
    • Fasterfrom http://cllctr.com/view/c2fdb4d2625e109069c843ea1bb99e50
    • from Test Driven Development Tutorial by Kirrily Robert
    • Faster● Shorter release cycle● Automation saves time● Find bugs earlier
    • Betterfrom http://www.nataliedee.com/archives/2005/sep/
    • Better● Greater code coverage● The courage to refactor● Prevent regression bugs● Improve your design
    • "Im not a great programmer;Im just a good programmerwith great habits." - Kent Beck
    • Testing the Old Way
    • TDD
    • TDD
    • How to do TDD?● Design: figure out what you want to do● Test: write a test to express the design ○ It should FAIL● Implement: write the code● Test again ○ It should PASS
    • DesignWe need a method add(), which takes two parameters and addthem together, then it will return the result.
    • Test
    • FAILjava.lang.AssertionError: expected:<2> but was:<0>...at tw.idv.haocheng.play.CalculatorTest.one_plus_one_is_two(CalculatorTest.java:20)
    • Implement
    • PASS
    • Write the least codeto make the test pass
    • More Test
    • FAILjava.lang.AssertionError: expected:<4> but was:<2>...at tw.idv.haocheng.play.CalculatorTest.two_plus_two_is_four(CalculatorTest.java:25)
    • Implement
    • PASS
    • DesignThe add() method only accept positive numbers
    • Test
    • FAILjava.lang.AssertionError: IllegalArgumentException expectedat org.junit.Assert.fail(Assert.java:91)at tw.idv.haocheng.play.CalculatorTest.negative_numbers_will_throw_exception(CalculatorTest.java:32)
    • Implement
    • PASS
    • from http://www.oracle.com/
    • DesignWe need a addNewCustomer()method that will save a customer record in Database
    • Test
    • Test
    • FAILjava.lang.NullPointerExceptionat tw.idv.haocheng.CustomerDAOTest.addNewCustomer(CustomerDAOTest.java:24)
    • Implement
    • PASS
    • from https://www.google.com/accounts/NewAccount
    • Design We hava a page that usercan apply for a new account
    • Test
    • Test
    • FAILwicket.markup.MarkupException: Unable to findcomponent with id accountFormPanel in[MarkupContainer ....at ngc.account.wicket.edit.CreateAccountPageTest.setUp(CreateAccountPageTest.java:49)
    • Implement
    • PASS
    • Unit Test Frameworks● Java - JUnit● Python - PyUnit● PHP - PHPUnit● Ruby - Test:Unit● Javascript - Jasmine● .Net - NUnit
    • Theres No Silver Bulletfrom http://www.penn-olson.com/2009/12/22/social-media-the-silver-bullet/
    • Costsfrom http://ora-pl-sql.blogspot.com/2011/05/database-costs.html
    • It takes time...from http://chunkeat626.blogspot.com/2010_11_01_archive.html
    • Need tomaintain tests
    • TDD is not suitable for... from http://www.flickr.com/photos/ilike/2443295369/
    • from http://tw.gamelet.com/game.do?code=heroes
    • from http://dilbert.com/
    • But how do I start??from http://zekjevets.blogspot.com/2010/02/alternative-racism.html
    • from http://www.alexbolboaca.ro/wordpress/the-remote-pair-programming-tour
    • Suggestions● Prepare tools and environments● Learn to write Unit test● Start from easy ones
    • Reading List● The Bowling Game Kata● Unit Testing Guidelines● Why are we embarrassed to admit that we don’t know how to write tests? (中譯版本)● "The Clean Code Talks -- Unit Testing"● Top 10 things which make your code hard to test
    • References - Test-Driven Development● Test Driven Development Tutorial by Kirrily Robert● Engineer Notebook: An Extreme Programming Episode by Robert C. Martin and Robert S. Koss● Technical Debt by Martin Fowler● InfoQ: Testing Misconceptions by Liam OConnor● Unit Test Isolation● Erratic Test● Singletons are Evil● RSpec 讓你愛上寫測試