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Coding dojo - TDD

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Steve Zhang
Steve Zhang

The document discusses the basics of test-driven development (TDD) including the three laws of TDD, the arrange-act-assert framework, faking dependencies, refactoring, characteristics of good unit tests, test method structure, and provides an example kata to demonstrate TDD with a string calculator.

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Coding Dojo - TDD Basics Steve Zhang
Coding dojo - TDD
3 Laws of TDD First Law: You may not write production code until you have written a failing unit test. Second Law: You may not write more of a unit test than is sufficient to fail, and not compiling Third Law: You may not write more production code than is sufficient to pass the currently Clean Code, p122 ; Robert Martin
Arrange Act -Assert
Fake It! Fake it till you make it Triangulation
As the tests get more specific, the code gets more generic. - Uncle Bob
Refactoring Change code without changing its behavior Refactoring != Redesign Remove the Fake Remove Duplication Refactor both test code and production code
F.I.R.S.T. Unit Tests Fast Independent Repeatable Self-validating Timely Clean Code, pp 132-133 ; Robert Martin
Test Methods Single assert No conditional logic Standard format Setup Exercise Verify Teardown
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Lets Start! Kata: StringCalculator Test method Example add_With_Empty_String_Returns_Zero()

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Coding dojo - TDD

  • 1. Coding Dojo - TDD Basics Steve Zhang
  • 3. 3 Laws of TDD First Law: You may not write production code until you have written a failing unit test. Second Law: You may not write more of a unit test than is sufficient to fail, and not compiling Third Law: You may not write more production code than is sufficient to pass the currently Clean Code, p122 ; Robert Martin
  • 4. Arrange Act -Assert
  • 5. Fake It! Fake it till you make it Triangulation
  • 6. As the tests get more specific, the code gets more generic. - Uncle Bob
  • 7. Refactoring Change code without changing its behavior Refactoring != Redesign Remove the Fake Remove Duplication Refactor both test code and production code
  • 8. F.I.R.S.T. Unit Tests Fast Independent Repeatable Self-validating Timely Clean Code, pp 132-133 ; Robert Martin
  • 9. Test Methods Single assert No conditional logic Standard format Setup Exercise Verify Teardown
  • 11. Lets Start! Kata: StringCalculator Test method Example add_With_Empty_String_Returns_Zero()

Editor's Notes

  1. Arrange all the things needed to exercise the code Act on the code you want to verify Assert that the code worked as expected
  2. Robert Martin uncle bob OO design guru - S.O.L.I.D. principles One of 17 formulators of Agile manifesto. Manifesto his idea One founder of Craftsmanship movement. Manifesto for Software Craftsmanship. Fast Must be able to run quickly. <10 minutes ideal Independent No test should depend on another. Order should not matter. Repeatable Should be able to run them at any stage, development, QA, production Timely - Created with code
  3. Having a single assert is an ideal. The idea is that the test should test ONLY ONE THING. In practice you might find a couple of asserts are needed, but try to keep it to one.