04-tdd.md

now you know the tooling!

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Let's use testing to DRIVE our development!

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Recap: Traditional approach

• Design
• Imlementation
• Test

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Drawbacks when writing tests at end

• low test coverage
• late testing: rethink problem
• knowledge of implementation: changes how tests are written
• not automated

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Test-Driven Development (TDD)

• Design
• Test
• Implementation

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TDD Workflow

• Red
• Green
• Refactor

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• no code without test
• untested code should not go live
• baby steps: only write code to make test pass

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green bar pattern

• "fake it til you make it"
• triangulation
• obvious implementation

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Advantages of TDD

• high test coverage
• increases modularity
• improves maintainability
• implicit documentation

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let's code

Fizz-Buzz Kata

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Schools of TDD

• Classical
  • aka Detroit, Chicago, "inside-out", "fake it til you make it"
  • K. Beck: Test-Driven Development By Example
• London
  • aka moquist, "outside-in"
  • Freeman & Pryce: Growing Object Oriented Software Guided by Tests
• Munich: David Voelkl
• Hamburg: Ralph Westpfahl