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.

You can watch the video here (in Chinese):



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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: // ,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:● 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
  • Test Myths
  • I have no time for testing
  • Technical Debt from
  • My code isBUG-FREE!
  • from
  • QA will do the testing
  • Black Box Testing from
  • Fasterfrom
  • from Test Driven Development Tutorial by Kirrily Robert
  • Faster● Shorter release cycle● Automation saves time● Find bugs earlier
  • Betterfrom
  • 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>
  • Implement
  • PASS
  • Write the least codeto make the test pass
  • More Test
  • FAILjava.lang.AssertionError: expected:<4> but was:<2>
  • Implement
  • PASS
  • DesignThe add() method only accept positive numbers
  • Test
  • FAILjava.lang.AssertionError: IllegalArgumentException expectedat
  • Implement
  • PASS
  • from
  • DesignWe need a addNewCustomer()method that will save a customer record in Database
  • Test
  • Test
  • FAILjava.lang.NullPointerExceptionat tw.idv.haocheng.CustomerDAOTest.addNewCustomer(
  • Implement
  • PASS
  • from
  • 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 ngc.account.wicket.edit.CreateAccountPageTest.setUp(
  • Implement
  • PASS
  • Unit Test Frameworks● Java - JUnit● Python - PyUnit● PHP - PHPUnit● Ruby - Test:Unit● Javascript - Jasmine● .Net - NUnit
  • Theres No Silver Bulletfrom
  • Costsfrom
  • It takes time...from
  • Need tomaintain tests
  • TDD is not suitable for... from
  • from
  • from
  • But how do I start??from
  • from
  • 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