The Art of Unit Testing Jessica Cecilia Budianto | Software Engineer - Web Platform 

Agenda ● Definition ● Principles ● Structure ● Preferences ● Practice 

Definition 

The benefits ● Helps to detect potential bug in code ● Reflects current code quality ● Made sure the code still works properly after refactor / major changes ● Documents the features and user flows of our code ● Trains our mindset to be a better software developer ○ How user interacts with our code ○ How edge cases and error might arise from our logic ○ Improves attention to detail 

Principles 

Fast It shouldn’t take long 🤔 

Isolated / Independent Not depending on other test cases 

Repeatable Not relying on e.g: network connection 

Self Validating A test should immediately acknowledges whether it succeeds 

Timely A test should be able to be written before development even started 

Understandable A test should be like telling a story 

Stucture 

General Test Structure 

Preferences 

Top down vs Bottom up 

https://kentcdodds.com/blog/write-tests 

Test Driven Development (TDD) 

But the downsides… ● Too focused on testing and making it passed ● Time consuming ● Harder for big codebase ● Even harder if it’s legacy code ● Might write a wrong test or miss the edge cases instead 

Behavior Driven Development (BDD) 

Practice 

Github: https://github.com/jessicacb12/ basic-calculator Vercel: https://basic-calculator-psi.vercel.app/ 

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Unit Testing will not just affect your code quality, but also your collaboration with stakeholders